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Drake R8B side by side with an Icom 756 PRO III
Anyone interested in having a look at a side by side comparison between the
venerable Drake R8B and Icom's latest digital transceiver offering the 756 PRO III can do so at http://www.dxing.info/equipment/icom_ic756_plimmer.dx The Icom has some impressive features for a SW DXer with performance to match -- John Plimmer, Montagu, Western Cape Province, South Africa South 33 d 47 m 32 s, East 20 d 07 m 32 s Icom IC-756 PRO III with MW mods RX Drake R8B, SW8 & ERGO software Sony 7600D GE SRIII BW XCR 30, Braun T1000, Sangean 818 & 803A. Hallicrafters SX-100, Eddystone 940 GE circa 50's radiogram Antenna's RF Systems DX 1 Pro, Datong AD-270 Kiwa MW Loop |
"John Plimmer" wrote in message ... Anyone interested in having a look at a side by side comparison between the venerable Drake R8B and Icom's latest digital transceiver offering the 756 PRO III can do so at http://www.dxing.info/equipment/icom_ic756_plimmer.dx The Icom has some impressive features for a SW DXer with performance to match Nice job John- and very much appreciated. I am using the original 756PRO and find it to be an exceptional LF--HF RX. For the LF experimental band, the ability to precisely set the BFO offset makes it possible to run ARGO in the narrowest of BW and be certain the signal will fall right where it should. I too would like sync detection, but find that tuning in the 1Hz step mode allows fantastic Exhaulted carrier detection. The scope is a real plus, and would be very much missed on any other rig. I run line audio out to a HiFi amp and find the audio superb, but lacking ( as you mentioned) if I just use another speaker on the 8 Ohm output of the Icom. 73, Dale W4OP for PAR Electronics, Inc. |
"Dale Parfitt" wrote in message news:SH3Cd.15352$Y57.9979@trnddc08... "John Plimmer" wrote in message ... Anyone interested in having a look at a side by side comparison between the venerable Drake R8B and Icom's latest digital transceiver offering the 756 PRO III can do so at http://www.dxing.info/equipment/icom_ic756_plimmer.dx The Icom has some impressive features for a SW DXer with performance to match Nice job John- and very much appreciated. I am using the original 756PRO and find it to be an exceptional LF--HF RX. For the LF experimental band, the ability to precisely set the BFO offset makes it possible to run ARGO in the narrowest of BW and be certain the signal will fall right where it should. I too would like sync detection, but find that tuning in the 1Hz step mode allows fantastic Exhaulted carrier detection. The scope is a real plus, and would be very much missed on any other rig. I run line audio out to a HiFi amp and find the audio superb, but lacking ( as you mentioned) if I just use another speaker on the 8 Ohm output of the Icom. 73, Dale W4OP for PAR Electronics, Inc. I have a R75 and other radios but my question applies is basic. Exactly how is the 1 Hz steps best used in ECSS? I read that in AM one should tune in up or down 2.5Kz one half an AM bandwidth to get best results? Is this right?? What is it for SSB?? Thanks Lucky |
Thanks for the review. It's very interesting.
I wonder: Why doesn't the Icom 756 Pro III have sync detection? Does any one know? There has to be some interesting explanation of this, given that we're talking about a $2000 unit. |
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John Plimmer wrote: Anyone interested in having a look at a side by side comparison between the venerable Drake R8B and Icom's latest digital transceiver offering the 756 PRO III can do so at http://www.dxing.info/equipment/icom_ic756_plimmer.dx The Icom has some impressive features for a SW DXer with performance to match Pricewise... after reading the review, I'd have to say that the R8B still wins, hands down, no question. dxAce Michigan USA -- John Plimmer, Montagu, Western Cape Province, South Africa South 33 d 47 m 32 s, East 20 d 07 m 32 s Icom IC-756 PRO III with MW mods RX Drake R8B, SW8 & ERGO software Sony 7600D GE SRIII BW XCR 30, Braun T1000, Sangean 818 & 803A. Hallicrafters SX-100, Eddystone 940 GE circa 50's radiogram Antenna's RF Systems DX 1 Pro, Datong AD-270 Kiwa MW Loop |
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Volker Tonn wrote:
I have a Sony 2001D/ 2010 and a NRD-525. The NRD has no sync detection and it runs circles around the Sony in *every* aspect. It should! I just switch to SSB-mode selecting the sideband and the bandwidth wich is working best. I'm rarely listenig in AM-mode. If you had a good sync detector, you might listen more in AM mode. A good sync detector basically provides auto-ECSS. -- Brian Denley http://home.comcast.net/~b.denley/index.html |
"John Plimmer" wrote in message ... Anyone interested in having a look at a side by side comparison between the venerable Drake R8B and Icom's latest digital transceiver offering the 756 PRO III can do so at http://www.dxing.info/equipment/icom_ic756_plimmer.dx The Icom has some impressive features for a SW DXer with performance to match Interesting article, but man, "venerable Drake R8B"?? When I think "venerable", I think a Hallicrafters SX-100 or a Hammarlund HQ-180AC. I must be getting old. --Mike L. |
There are many similarities in the 756Pro series. The ProII and ProIII were
"evolutionary" improvements, not major changes in performance compared to the original 756Pro (which I own, and use for tropical bands and TP MW DXing). It becomes a much more interesting value comparion when it's between the R8B and a used 756Pro (~$1400-1500 on Ebay), a used 756ProII (~$1600) or even a new 756ProII (currently around $2100 from ham outlets). I agree with all of John's comments in his review of the 757ProIII as applying to the 756Pro. John and I had a lot of email exchanges before he found his excellent deal on a new ProIII, and the only area we disagree on is the usefulness and ease of adjustment for the manual notch. I find it's 70 db depth to be phenomenal and simple to operate. I prefer it over the auto notch, which works well. BTW, the IC-746Pro's AM detector is a synchronous type, and a fine one according to Dallas Lankford. Too bad that ICOM makes no mention of it, but an ICOM tech confirmed to Dallas about the synch detector. There are MANY circuit similarities between the 746Pro and the 756Pro, and perhaps the 756ProII/III also has the same detector? Dallas says in his 756Pro review & modifications article at www.kongsfjord.no : "Here are some things that put the 746P at the top of the heap. The AM detector is an AM synchronous detector. Why ICOM doesn't advertise this feature of the 746P is a mystery to me. I discovered it merely by noticing that it sounded like an AM synchronous detector and asking ICOM Technical Support if it was. They confirmed what my ears had already told me. And it is not just any old AM synchronous detector. It is an outstanding AM synchronous detector. It doesn't lose lock (no growling on extremely weak signals fading in and out of the ambient noise floor) and you can tune the signal with the AM carrier anywhere you please in the passband, and even out of the passband, and still no growling. In other words, the 746P AMSD is completely transparent to the user. You never know it is there except that the quality of AM reception is better than with an ordinary AM detector for some weak signals at the ambient noise floor and for some strongly fading signals, and better than ECSS." --------------------------------------- For my money, a mint-cond., late serial number 756Pro was an excellent value. I've had a Ten-Tec RX340 in the shack for a month, and it performed significantly worse on tough DX than my modded R-75 and the RA6790GM I used to have. Guy Atkins Puyallup, WA USA "dxAce" wrote in message ... Pricewise... after reading the review, I'd have to say that the R8B still wins, hands down, no question. dxAce Michigan USA |
Mike you are indeed getting old like me.
The Hallicrafters SX-100 and Hammarlund HQ-180AC were indeed great radio's in their day. But time marches on - "time and tide waits for no man!" Undoubtedly the Drake R8B will be a historic radio of its time, the nineties. So too will be the new digital radio's of the new millennium. The old boatanchors are now history, surpassed by the awesome capabilities of the new era digital radio's. BTW I cut my teeth on an Eddystone 840 Best wishes for good DX in the New Year -- John Plimmer, Montagu, Western Cape Province, South Africa "Michael Lawson" wrote in message ... "John Plimmer" wrote in message ... Anyone interested in having a look at a side by side comparison between the venerable Drake R8B and Icom's latest digital transceiver offering the 756 PRO III can do so at http://www.dxing.info/equipment/icom_ic756_plimmer.dx The Icom has some impressive features for a SW DXer with performance to match Interesting article, but man, "venerable Drake R8B"?? When I think "venerable", I think a Hallicrafters SX-100 or a Hammarlund HQ-180AC. I must be getting old. --Mike L. |
Brian Denley schrieb: Volker Tonn wrote: I have a Sony 2001D/ 2010 and a NRD-525. The NRD has no sync detection and it runs circles around the Sony in *every* aspect. It should! Yes :-) I just switch to SSB-mode selecting the sideband and the bandwidth wich is working best. I'm rarely listenig in AM-mode. If you had a good sync detector, you might listen more in AM mode. A good sync detector basically provides auto-ECSS. AFAIK the NRD-525 *is* in ECSS-mode when switched to AM. It allways adds its own carrier frequency, except when switched to FM mode. Nontheless I like SSB much more than AM. |
Volker Tonn wrote: Brian Denley schrieb: Volker Tonn wrote: I have a Sony 2001D/ 2010 and a NRD-525. The NRD has no sync detection and it runs circles around the Sony in *every* aspect. It should! Yes :-) I just switch to SSB-mode selecting the sideband and the bandwidth wich is working best. I'm rarely listenig in AM-mode. If you had a good sync detector, you might listen more in AM mode. A good sync detector basically provides auto-ECSS. AFAIK the NRD-525 *is* in ECSS-mode when switched to AM. It allways adds its own carrier frequency, except when switched to FM mode. Never heard that before, but who knows. dxAce Michigan USA |
Volker Tonn wrote:
Brian Denley schrieb: Volker Tonn wrote: I have a Sony 2001D/ 2010 and a NRD-525. The NRD has no sync detection and it runs circles around the Sony in *every* aspect. It should! Yes :-) I just switch to SSB-mode selecting the sideband and the bandwidth wich is working best. I'm rarely listenig in AM-mode. If you had a good sync detector, you might listen more in AM mode. A good sync detector basically provides auto-ECSS. AFAIK the NRD-525 *is* in ECSS-mode when switched to AM. It allways adds its own carrier frequency, except when switched to FM mode. Nontheless I like SSB much more than AM. Actually it is true ECSS. The carrier is derived form the input signal so there is no need for careful tuning. craigm |
craigm wrote: Volker Tonn wrote: Brian Denley schrieb: Volker Tonn wrote: I have a Sony 2001D/ 2010 and a NRD-525. The NRD has no sync detection and it runs circles around the Sony in *every* aspect. It should! Yes :-) I just switch to SSB-mode selecting the sideband and the bandwidth wich is working best. I'm rarely listenig in AM-mode. If you had a good sync detector, you might listen more in AM mode. A good sync detector basically provides auto-ECSS. AFAIK the NRD-525 *is* in ECSS-mode when switched to AM. It allways adds its own carrier frequency, except when switched to FM mode. Nontheless I like SSB much more than AM. Actually it is true ECSS. The carrier is derived form the input signal so there is no need for careful tuning. Is it selecting a particular sideband? craigm |
dxAce schrieb: Is it selecting a particular sideband? No. But actually there is no need for that -IMHO-. Tuning to zerobeat in SSB is easy and rock stable. Switching to SSB is easily done without shifting. And with some additional IF-filters you can switch to the bandwidth working best in conjunktion with bandpass shift. |
Volker Tonn wrote: dxAce schrieb: Is it selecting a particular sideband? No. But actually there is no need for that -IMHO-. Tuning to zerobeat in SSB is easy and rock stable. Switching to SSB is easily done without shifting. And with some additional IF-filters you can switch to the bandwidth working best in conjunktion with bandpass shift. OK, I was wondering about the ECSS in AM mode. |
Volker Tonn wrote:
dxAce schrieb: Is it selecting a particular sideband? No. But actually there is no need for that -IMHO-. Tuning to zerobeat in SSB is easy and rock stable. Switching to SSB is easily done without shifting. And with some additional IF-filters you can switch to the bandwidth working best in conjunktion with bandpass shift. Volker: Yes but in true AM ECSS mode (syncronous demodulation), the zero beating is automatic and tracks. You don't have to keep adjusting. Drift doesn't matter, music comes in perfectly, it's locked! That is superior to any manual ECSS mode. -- Brian Denley http://home.comcast.net/~b.denley/index.html |
Guy Atkins wrote:
I've had a Ten-Tec RX340 in the shack for a month, and it performed significantly worse on tough DX than my modded R-75 and the RA6790GM I used to have. Guy Atkins Puyallup, WA USA Any RX-340 that gets outperformed by a R75 needs to be taken to the shop. -- Brian Denley http://home.comcast.net/~b.denley/index.html |
"Brian Denley" wrote:
Guy Atkins wrote: I've had a Ten-Tec RX340 in the shack for a month, and it performed significantly worse on tough DX than my modded R-75 and the RA6790GM I used to have. Guy Atkins Puyallup, WA USA Any RX-340 that gets outperformed by a R75 needs to be taken to the shop. I would tend to agree, unless his definition of "tough DX" is extremely narrow. -- Eric F. Richards, "Nature abhors a vacuum tube." -- Myron Glass, often attributed to J. R. Pierce, Bell Labs, c. 1940 |
"Eric F. Richards" wrote: "Brian Denley" wrote: Guy Atkins wrote: I've had a Ten-Tec RX340 in the shack for a month, and it performed significantly worse on tough DX than my modded R-75 and the RA6790GM I used to have. Guy Atkins Puyallup, WA USA Any RX-340 that gets outperformed by a R75 needs to be taken to the shop. I would tend to agree, unless his definition of "tough DX" is extremely narrow. I'm fairly certain that Guy knows what 'tough DX' is... He's a 'dxAce' also! dxAce Michigan USA |
Actually, Guy, highly respected DXer that he is, is not the only one of the
serious DXer's who have found that the Ten Tec RX-340 does not come up with the cookies when the DXing gets tough. I have seen at least two other serious DXers in Europe who did evaluations of the Ten Tec RX-340 comment that it does not cut the cake when things get serious. On another tack, I can confirm that in my use of the Icom 756 PRO III, it does not have synchronous detection and that the AM audio definitely breaks up as a result of this shortcoming - putting the RX in ECSS mode for AM reception does improve matters, however it comes nowhere near the Drake R8B's performance of superb AM broadcast band reception when its in "sync" mode. In another forum Bjarne Mjelde wrote on 050105: "One thing that is interesting to note is that the 756Pro series do not use AM Sync Detector, while the 746Pro (which is identical, RF and IF wise), do. My experience with the 746Pro is that AM quality is excellent. For those who care more about AM quality than fancy displays (one would be better off with a spectrum analyser anyway), the 746Pro would be the one to choose. And it is considerably cheaper too..." Bjarne www.kongsfjord.no Happy DXing! -- John Plimmer, Montagu, Western Cape Province, South Africa Icom IC-756 PRO III with MW mods RX Drake R8B, SW8 & ERGO software Antenna's RF Systems DX 1 Pro, Datong AD-270 Kiwa MW Loop "Eric F. Richards" wrote: "Brian Denley" wrote: Guy Atkins wrote: I've had a Ten-Tec RX340 in the shack for a month, and it performed significantly worse on tough DX than my modded R-75 and the RA6790GM I used to have. Guy Atkins Puyallup, WA USA Any RX-340 that gets outperformed by a R75 needs to be taken to the shop. I would tend to agree, unless his definition of "tough DX" is extremely narrow. I'm fairly certain that Guy knows what 'tough DX' is... He's a 'dxAce' also! dxAce Michigan USA |
Brian Denley schrieb: Volker: Yes but in true AM ECSS mode (syncronous demodulation), the zero beating is automatic and tracks. You don't have to keep adjusting. Drift doesn't matter, music comes in perfectly, it's locked! That is superior to any manual ECSS mode. I've ***never*** seen my NRD-525 drinfting.... I just fire it up and it sits on the frequency like a Buddha with a smile :-) So *I* don't worry.... |
"John Plimmer" wrote:
Actually, Guy, highly respected DXer that he is, is not the only one of the serious DXer's who have found that the Ten Tec RX-340 does not come up with the cookies when the DXing gets tough. I have seen at least two other serious DXers in Europe who did evaluations of the Ten Tec RX-340 comment that it does not cut the cake when things get serious. Okay, fine, but what do "come up with the cookies" and "cut the cake" *mean*? What, specifically, did they find that fell flat? There are things I can think of that it could do better, but they fall into the "annoyance" range rather than the "just not worth it" range. -- Eric F. Richards, "Nature abhors a vacuum tube." -- Myron Glass, often attributed to J. R. Pierce, Bell Labs, c. 1940 |
"Eric F. Richards" wrote in message
... "Brian Denley" wrote: Guy Atkins wrote: I've had a Ten-Tec RX340 in the shack for a month, and it performed significantly worse on tough DX than my modded R-75 and the RA6790GM I used to have. ------------------------------------------- Any RX-340 that gets outperformed by a R75 needs to be taken to the shop. I would tend to agree, unless his definition of "tough DX" is extremely narrow. Hi Eric, I should clarify that I had TWO RX-340s on loan, and both performed equally sub-par at home. On DXpeditions away from strong RF sources, they are fine receivers. I'll quote from my reply today to Larry Magne, who heard through the grapevine that I'd done some A-B-C receiver comparisons involving a RX-340 and wanted more information before IBS plunks down $4,000 for another sample to test. Sorry for the length of this post, but it addresses the questions brought up: ----------------------------------------------------------------------- "Thanks for the note and questions about the RX-340. I do not own a RX-340, but have DXed occasionally with two different ones at coastal DXpeditions, and this fall I had a close friend's RX-340 on loan for an entire month. I also had another friend's RX-340 here for a couple of weeks. I used both RX-340s extensively in October and November, along side my modified R-75 and also a Racal RA6790GM (with narrower, 10-kHz roofing filters). Each radio was fed with signals from my Beverage antennas through a Mini-Circuits splitter. Note that I didn't have both RX-340s here at the same time; one followed the other. My impression of the Ten-Tecs at DXpeditions has always been very good. However, at our group's usual DXpedition site of Grayland, WA, there are no nearby strong RF sources to cause problems. At home it's a different matter, unfortunately. My permanent Beverages are aimed at my favorite Asian and subcontinental targets, but the wires are pointed "down the barrel" toward Seattle/Tacoma area powerhouses on mediumwave (I live to the east of Tacoma, and my targets--and pests--are generally to the west). I have a number of locals that are in the S-9 + 50db range on my receivers and a few at S-9 + 65db. Despite the RF alley I manage to log trans-Pacific MW DX from home; Japan, Korea, and China stations were in abundance this past fall! On the tropical bands I switch in a Kiwa BCB filter + Extension Filter to ease the load on the front ends of receivers. Despite the two highpass filters inline, the RX-340s struggled to hear weak DX on the tropical bands and above. Both my R-75 and RA6790GM performed well and practically identical under the same conditions. I initially believed the problem was RF blocking of the RX-340s' front end, but Dallas Lankford told me he thinks it's a matter of the RX-340 circuitry reducing the gain in order to "protect" the DSP AGC loop. When the DX was audible on the RX-340s, it was always weaker and with poorer intelligibility than the R-75 and RA6790GM. I did numerous tests throughout the month, and never did the Ten-Tec equal the performance of the other receivers. They were also the worst performers when the trans-Pacific MW DX was coming in. I'm not aware of any production changes that would affect the RX-340 in this way. Attached are two short MP3 recordings from my files, demonstrating the audio from an RX-340 and my R-75. The station is AIR Bangalore on 9425, shortly after it rose above threshold level and began to be slightly readable. The antenna was my 700 ft. Northwest Beverage, fed equally through the Mini-Circuits splitter. As you'll note, there's just noise from the Ten-Tec's MP3 recording. I have another set of recordings from 3320 kHz (RX-340, R-75 and RA6790GM), and the results are similar. By the way, Ten-Tec "guru" Carl Moreschi, N4PY, developed a mod for the front end of the radio that I installed in my friends' RX-340s. It's a 4 kHz Kiwa filter module that can be switched in and out of the 2nd Mixer/IF Board via a relay. He claims it provides over 100 db dynamic range for signals between 5 and 10 kHz removed from a strong signal. I installed the mod in the two RX-340s that I had on loan. It worked very well--at times-- on mediumwave to restore sensitivity close to a powerhouse. Unfortunately there was an overall attenuation that N4PY and I could never figure out, and after much head-scratching and experimenting, my friends and I gave up on the mod. They didn't want to sacrifice any performance of their RX-340s in the low-noise, low-RF DXpedition environments we enjoy so much. I was as surprised as anyone by the lackluster showing of these $4K receivers! My R-75 has numerous mods including a narrower roofing filter, but I didn't think it could surpass (or equal) a RX-340 under equal, but difficult RF alley conditions. I thought the Racal with its twin roofing filters mod *might* give the RX-340 a challenge, but I never expected it to consistently better the Ten-Tec. I'll note that every "serious" communications receiver used by the Grayland participants has performed very similar to the others, time and time again. Our core group of DXers has travelled to the WA coast since 1989 for 2-3 times per year, and we've had ample opportunity to compare our receivers. Particularly on the foreign mediumwave stations, you'd be hard pressed to tell any differences in weak DX readability between a $500 R-75, a $1500 R8B, or a $4000 RX-340! It wasn't until I had a chance to use the RX-340s in my suburban area that I discovered the surprising differences. As a side note, I recently sold my Racal and bought an ICOM IC-756Pro transceiver through Ebay for $1500 and I am extremely pleased with it. I wanted to have an all-DSP communications receiver at a more modest price than the RX-340, but didn't like IP3 & close-in dynamic range numbers I'd been reading for the Winradio G3 series (which I otherwise liked a lot). The 756Pro *consistently* outperforms my modded R-75 at home, and I look forward to getting them to Grayland for comparisons in that optimum environment. The 24-bit DSP and AGC within the DSP loop evidently contributes higly to the performance of ICOM's 756Pro series. I know of three other DXers who have now bought 756ProII and 756ProIII models based largely on my findings and posted reviews. They are also tropical band and foreign mediumwave DXers. At a price of ~$1700 used, or $2100 new, the IC-756ProII is quite a receiver, even for receive-only DX. You gotta love that spectrum display, too! My apologies for the lengthy reply, Larry, but I felt it best to give you a full backgrounder to my disappointing experience with the two RX-340s I had on loan. " --------------------------------------------------------------------------- If anyone wants to listen to the MP3 samples referred to above, email me at (remove the NOSPAM) and I'll send you the MP3's as attachments. I'm not out to bash the RX-340, as I better things to do, such as DXing! If anyone's interested in a bit of my background that briefly describes my hobby qualifications (ie., I'm not a newcomer at DXing or evaluating receivers through hands-on use), please see this bio at dxing.info: http://www.dxing.info/about/dxers/atkins.dx Guy Atkins Puyallup, WA USA |
4nradio wrote: "Eric F. Richards" wrote in message ... "Brian Denley" wrote: Guy Atkins wrote: I've had a Ten-Tec RX340 in the shack for a month, and it performed significantly worse on tough DX than my modded R-75 and the RA6790GM I used to have. ------------------------------------------- Any RX-340 that gets outperformed by a R75 needs to be taken to the shop. I would tend to agree, unless his definition of "tough DX" is extremely narrow. Hi Eric, I should clarify that I had TWO RX-340s on loan, and both performed equally sub-par at home. On DXpeditions away from strong RF sources, they are fine receivers. I'll quote from my reply today to Larry Magne, who heard through the grapevine that I'd done some A-B-C receiver comparisons involving a RX-340 and wanted more information before IBS plunks down $4,000 for another sample to test. Sorry for the length of this post, but it addresses the questions brought up: ----------------------------------------------------------------------- "Thanks for the note and questions about the RX-340. I do not own a RX-340, but have DXed occasionally with two different ones at coastal DXpeditions, and this fall I had a close friend's RX-340 on loan for an entire month. I also had another friend's RX-340 here for a couple of weeks. I used both RX-340s extensively in October and November, along side my modified R-75 and also a Racal RA6790GM (with narrower, 10-kHz roofing filters). Each radio was fed with signals from my Beverage antennas through a Mini-Circuits splitter. Note that I didn't have both RX-340s here at the same time; one followed the other. My impression of the Ten-Tecs at DXpeditions has always been very good. However, at our group's usual DXpedition site of Grayland, WA, there are no nearby strong RF sources to cause problems. At home it's a different matter, unfortunately. My permanent Beverages are aimed at my favorite Asian and subcontinental targets, but the wires are pointed "down the barrel" toward Seattle/Tacoma area powerhouses on mediumwave (I live to the east of Tacoma, and my targets--and pests--are generally to the west). I have a number of locals that are in the S-9 + 50db range on my receivers and a few at S-9 + 65db. Despite the RF alley I manage to log trans-Pacific MW DX from home; Japan, Korea, and China stations were in abundance this past fall! On the tropical bands I switch in a Kiwa BCB filter + Extension Filter to ease the load on the front ends of receivers. Despite the two highpass filters inline, the RX-340s struggled to hear weak DX on the tropical bands and above. Both my R-75 and RA6790GM performed well and practically identical under the same conditions. I initially believed the problem was RF blocking of the RX-340s' front end, but Dallas Lankford told me he thinks it's a matter of the RX-340 circuitry reducing the gain in order to "protect" the DSP AGC loop. When the DX was audible on the RX-340s, it was always weaker and with poorer intelligibility than the R-75 and RA6790GM. I did numerous tests throughout the month, and never did the Ten-Tec equal the performance of the other receivers. They were also the worst performers when the trans-Pacific MW DX was coming in. I'm not aware of any production changes that would affect the RX-340 in this way. Attached are two short MP3 recordings from my files, demonstrating the audio from an RX-340 and my R-75. The station is AIR Bangalore on 9425, shortly after it rose above threshold level and began to be slightly readable. The antenna was my 700 ft. Northwest Beverage, fed equally through the Mini-Circuits splitter. As you'll note, there's just noise from the Ten-Tec's MP3 recording. I have another set of recordings from 3320 kHz (RX-340, R-75 and RA6790GM), and the results are similar. By the way, Ten-Tec "guru" Carl Moreschi, N4PY, developed a mod for the front end of the radio that I installed in my friends' RX-340s. It's a 4 kHz Kiwa filter module that can be switched in and out of the 2nd Mixer/IF Board via a relay. He claims it provides over 100 db dynamic range for signals between 5 and 10 kHz removed from a strong signal. I installed the mod in the two RX-340s that I had on loan. It worked very well--at times-- on mediumwave to restore sensitivity close to a powerhouse. Unfortunately there was an overall attenuation that N4PY and I could never figure out, and after much head-scratching and experimenting, my friends and I gave up on the mod. They didn't want to sacrifice any performance of their RX-340s in the low-noise, low-RF DXpedition environments we enjoy so much. I was as surprised as anyone by the lackluster showing of these $4K receivers! My R-75 has numerous mods including a narrower roofing filter, but I didn't think it could surpass (or equal) a RX-340 under equal, but difficult RF alley conditions. I thought the Racal with its twin roofing filters mod *might* give the RX-340 a challenge, but I never expected it to consistently better the Ten-Tec. I'll note that every "serious" communications receiver used by the Grayland participants has performed very similar to the others, time and time again. Our core group of DXers has travelled to the WA coast since 1989 for 2-3 times per year, and we've had ample opportunity to compare our receivers. Particularly on the foreign mediumwave stations, you'd be hard pressed to tell any differences in weak DX readability between a $500 R-75, a $1500 R8B, or a $4000 RX-340! It wasn't until I had a chance to use the RX-340s in my suburban area that I discovered the surprising differences. As a side note, I recently sold my Racal and bought an ICOM IC-756Pro transceiver through Ebay for $1500 and I am extremely pleased with it. I wanted to have an all-DSP communications receiver at a more modest price than the RX-340, but didn't like IP3 & close-in dynamic range numbers I'd been reading for the Winradio G3 series (which I otherwise liked a lot). The 756Pro *consistently* outperforms my modded R-75 at home, and I look forward to getting them to Grayland for comparisons in that optimum environment. The 24-bit DSP and AGC within the DSP loop evidently contributes higly to the performance of ICOM's 756Pro series. I know of three other DXers who have now bought 756ProII and 756ProIII models based largely on my findings and posted reviews. They are also tropical band and foreign mediumwave DXers. At a price of ~$1700 used, or $2100 new, the IC-756ProII is quite a receiver, even for receive-only DX. You gotta love that spectrum display, too! My apologies for the lengthy reply, Larry, but I felt it best to give you a full backgrounder to my disappointing experience with the two RX-340s I had on loan. " --------------------------------------------------------------------------- If anyone wants to listen to the MP3 samples referred to above, email me at (remove the NOSPAM) and I'll send you the MP3's as attachments. I'm not out to bash the RX-340, as I better things to do, such as DXing! If anyone's interested in a bit of my background that briefly describes my hobby qualifications (ie., I'm not a newcomer at DXing or evaluating receivers through hands-on use), please see this bio at dxing.info: http://www.dxing.info/about/dxers/atkins.dx Guy Atkins Puyallup, WA USA I had a 'loan' of an RX340 some time back, I used it for several weeks and it was returned. Nice enough receiver, but certainly not worth the $4K price tag as I've stated here several times already. dxAce Michigan USA |
Hi, Guy,
Thanks for your post and the accompanying email. It is appreciated. Ironically, one of the reasons I went for the '340 was a very similar problem to what you describe. However, in my case, it was front-end overload on a level that the R-75 could not handle. My R-8500s, generally considered "inferior" to the '75, had no problems at all. A later test with a Drake R8B showed it had similar problems but handled them more gracefully. The situation was a 1000 foot Beverage, boresighted on a 50 kW flamethrower 85 miles away. Even at my home location, with a 400 foot wire oriented 120 degrees from the aforementioned Beverage, shows the antenna voltage in millivolts from that station. The '340 handles it with aplomb, but this isn't a close-in IP3 problem. The '75 did okay at home, but my WinRadio G303i can't cope with it. The WR is a great radio at many things, but it has trouble with close-in IP3 *and* front-end overload. A crowded band it can handle, but only if you aren't overwhelming the front end or the 22 kHz passband that goes into the sound card. Back to the '340: The two beefs I think of are the poor dynamic range and the relative harshness of white noise (static) when run through the I.F. I was wondering what you were finding. While your message doesn't suggest that the signals were *that* close in, they probably made it through the same pass band filter as your tropical stations. I've been aware of Carl's mod -- I just can't bring myself to cut traces on my '340 just yet. It would also be a cleaner mod if the narrow filter switched out when the bandwidth chosen by the front panel was wider than its skirt, but that would take a fair amount of reverse engineering of the code in the processor(s). As for your MP3s... I'd be very interested in hearing them! Perhaps, for others following this discussion, you can put them on a web page? If not, with your permission (and size permitting), I can do so. Regards, Eric "4nradio" wrote: "Eric F. Richards" wrote in message ... "Brian Denley" wrote: Guy Atkins wrote: I've had a Ten-Tec RX340 in the shack for a month, and it performed significantly worse on tough DX than my modded R-75 and the RA6790GM I used to have. ------------------------------------------- Any RX-340 that gets outperformed by a R75 needs to be taken to the shop. I would tend to agree, unless his definition of "tough DX" is extremely narrow. Hi Eric, I should clarify that I had TWO RX-340s on loan, and both performed equally sub-par at home. On DXpeditions away from strong RF sources, they are fine receivers. I'll quote from my reply today to Larry Magne, who heard through the grapevine that I'd done some A-B-C receiver comparisons involving a RX-340 and wanted more information before IBS plunks down $4,000 for another sample to test. Sorry for the length of this post, but it addresses the questions brought up: ----------------------------------------------------------------------- "Thanks for the note and questions about the RX-340. I do not own a RX-340, but have DXed occasionally with two different ones at coastal DXpeditions, and this fall I had a close friend's RX-340 on loan for an entire month. I also had another friend's RX-340 here for a couple of weeks. I used both RX-340s extensively in October and November, along side my modified R-75 and also a Racal RA6790GM (with narrower, 10-kHz roofing filters). Each radio was fed with signals from my Beverage antennas through a Mini-Circuits splitter. Note that I didn't have both RX-340s here at the same time; one followed the other. My impression of the Ten-Tecs at DXpeditions has always been very good. However, at our group's usual DXpedition site of Grayland, WA, there are no nearby strong RF sources to cause problems. At home it's a different matter, unfortunately. My permanent Beverages are aimed at my favorite Asian and subcontinental targets, but the wires are pointed "down the barrel" toward Seattle/Tacoma area powerhouses on mediumwave (I live to the east of Tacoma, and my targets--and pests--are generally to the west). I have a number of locals that are in the S-9 + 50db range on my receivers and a few at S-9 + 65db. Despite the RF alley I manage to log trans-Pacific MW DX from home; Japan, Korea, and China stations were in abundance this past fall! On the tropical bands I switch in a Kiwa BCB filter + Extension Filter to ease the load on the front ends of receivers. Despite the two highpass filters inline, the RX-340s struggled to hear weak DX on the tropical bands and above. Both my R-75 and RA6790GM performed well and practically identical under the same conditions. I initially believed the problem was RF blocking of the RX-340s' front end, but Dallas Lankford told me he thinks it's a matter of the RX-340 circuitry reducing the gain in order to "protect" the DSP AGC loop. When the DX was audible on the RX-340s, it was always weaker and with poorer intelligibility than the R-75 and RA6790GM. I did numerous tests throughout the month, and never did the Ten-Tec equal the performance of the other receivers. They were also the worst performers when the trans-Pacific MW DX was coming in. I'm not aware of any production changes that would affect the RX-340 in this way. Attached are two short MP3 recordings from my files, demonstrating the audio from an RX-340 and my R-75. The station is AIR Bangalore on 9425, shortly after it rose above threshold level and began to be slightly readable. The antenna was my 700 ft. Northwest Beverage, fed equally through the Mini-Circuits splitter. As you'll note, there's just noise from the Ten-Tec's MP3 recording. I have another set of recordings from 3320 kHz (RX-340, R-75 and RA6790GM), and the results are similar. By the way, Ten-Tec "guru" Carl Moreschi, N4PY, developed a mod for the front end of the radio that I installed in my friends' RX-340s. It's a 4 kHz Kiwa filter module that can be switched in and out of the 2nd Mixer/IF Board via a relay. He claims it provides over 100 db dynamic range for signals between 5 and 10 kHz removed from a strong signal. I installed the mod in the two RX-340s that I had on loan. It worked very well--at times-- on mediumwave to restore sensitivity close to a powerhouse. Unfortunately there was an overall attenuation that N4PY and I could never figure out, and after much head-scratching and experimenting, my friends and I gave up on the mod. They didn't want to sacrifice any performance of their RX-340s in the low-noise, low-RF DXpedition environments we enjoy so much. I was as surprised as anyone by the lackluster showing of these $4K receivers! My R-75 has numerous mods including a narrower roofing filter, but I didn't think it could surpass (or equal) a RX-340 under equal, but difficult RF alley conditions. I thought the Racal with its twin roofing filters mod *might* give the RX-340 a challenge, but I never expected it to consistently better the Ten-Tec. I'll note that every "serious" communications receiver used by the Grayland participants has performed very similar to the others, time and time again. Our core group of DXers has travelled to the WA coast since 1989 for 2-3 times per year, and we've had ample opportunity to compare our receivers. Particularly on the foreign mediumwave stations, you'd be hard pressed to tell any differences in weak DX readability between a $500 R-75, a $1500 R8B, or a $4000 RX-340! It wasn't until I had a chance to use the RX-340s in my suburban area that I discovered the surprising differences. As a side note, I recently sold my Racal and bought an ICOM IC-756Pro transceiver through Ebay for $1500 and I am extremely pleased with it. I wanted to have an all-DSP communications receiver at a more modest price than the RX-340, but didn't like IP3 & close-in dynamic range numbers I'd been reading for the Winradio G3 series (which I otherwise liked a lot). The 756Pro *consistently* outperforms my modded R-75 at home, and I look forward to getting them to Grayland for comparisons in that optimum environment. The 24-bit DSP and AGC within the DSP loop evidently contributes higly to the performance of ICOM's 756Pro series. I know of three other DXers who have now bought 756ProII and 756ProIII models based largely on my findings and posted reviews. They are also tropical band and foreign mediumwave DXers. At a price of ~$1700 used, or $2100 new, the IC-756ProII is quite a receiver, even for receive-only DX. You gotta love that spectrum display, too! My apologies for the lengthy reply, Larry, but I felt it best to give you a full backgrounder to my disappointing experience with the two RX-340s I had on loan. " --------------------------------------------------------------------------- If anyone wants to listen to the MP3 samples referred to above, email me at (remove the NOSPAM) and I'll send you the MP3's as attachments. I'm not out to bash the RX-340, as I better things to do, such as DXing! If anyone's interested in a bit of my background that briefly describes my hobby qualifications (ie., I'm not a newcomer at DXing or evaluating receivers through hands-on use), please see this bio at dxing.info: http://www.dxing.info/about/dxers/atkins.dx Guy Atkins Puyallup, WA USA -- Eric F. Richards, "Nature abhors a vacuum tube." -- Myron Glass, often attributed to J. R. Pierce, Bell Labs, c. 1940 |
Eric, if you look in the latest 2005 Passport you will see that the IP3 @ 5
Khz rating for the RX-340 is poor - this means that if you are DXing in MW or Tropical Bands with a strong station near your weaker target station, then the RX-340 can't resolve it, whereas various other radio's that have a much more respectable IP3 @ 5 Khz performance, like the AOR 7030, Drake R8B and Icom 75 will be able to resolve the weak signal whereas the RX-340 will not be able to do so. Close in DXing with nearby strong signals is a feature of trying to get weak stations that are 5 Khz or nearer to other more powerful signals. Several DXer's have indicated that Passports numbers/statistics are correct and that the RX-340 cannot render audible signals that are close by to more powerful stations. The Icom 756 PRO III is superb in this respect as I have indicated in my comparison review -- John Plimmer, Montagu, Western Cape Province, South Africa Icom IC-756 PRO III with MW mods RX Drake R8B, SW8 & ERGO software Antenna's RF Systems DX 1 Pro, Datong AD-270 Kiwa MW Loop "Eric F. Richards" wrote in message ... "John Plimmer" wrote: Actually, Guy, highly respected DXer that he is, is not the only one of the serious DXer's who have found that the Ten Tec RX-340 does not come up with the cookies when the DXing gets tough. I have seen at least two other serious DXers in Europe who did evaluations of the Ten Tec RX-340 comment that it does not cut the cake when things get serious. Okay, fine, but what do "come up with the cookies" and "cut the cake" *mean*? What, specifically, did they find that fell flat? There are things I can think of that it could do better, but they fall into the "annoyance" range rather than the "just not worth it" range. -- Eric F. Richards, "Nature abhors a vacuum tube." -- Myron Glass, often attributed to J. R. Pierce, Bell Labs, c. 1940 |
Hi Eric,
I took your advice and put the comparison files on my web site. I made about a dozen more comparison recordings originally, but kept these as the main examples. Note that the recording level on the R-75 clips are somewhat low; bump up the volume on your MP3 player to hear the audio better. All recordings were done with the receivers' mode (USB), bandwidth (3.3 or 4 kHz), and AGC (fast) matched as closely as possible. 1) All India Radio, Bangalore 9425 kHz, just past fade-in. http://www.guyatkins.com/files/r75_9425khz.mp3 audio's there, but poor. http://www.guyatkins.com/files/RX340_9425khz.mp3 mostly noise. 2) SABC Meyerton, 3320 kHz, during a poor propagation evening, an hour or so past Meyerton SR. http://www.guyatkins.com/files/r75_3320khz.mp3 weak signal audio. http://www.guyatkins.com/files/ra6790gm_3320khz.mp3 also weak, but slightly better on the Racal. http://www.guyatkins.com/files/RX340_3320khz.mp3 mostly noise. 3) Example of Carl Moreschi N4PY's RX-340 front end modification. Mod is switched in and out on a weaker MW station that's 10 kHz away from a powerful local (I forget the call letters of the weak station, but it was in Nampa, Idaho). The poorer/weaker portions of audio are the RX-340 "barefoot" without the mod, presumably indicating desensing/RF blocking occurring. http://www.guyatkins.com/files/RX340_Mod.mp3 Guy Atkins Puyallup, WA USA "Eric F. Richards" wrote in message ... SNIP Hi, Guy, As for your MP3s... I'd be very interested in hearing them! Perhaps, for others following this discussion, you can put them on a web page? If not, with your permission (and size permitting), I can do so. SNIP |
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