On Fri, 8 Feb 2013 10:57:03 -0800, (Dave Platt)
wrote:

In article ,
Jeff Liebermann wrote:

Any ideas how to eliminate cross channel intermodulation with good antenna?
Or right antenna?

You're antenna isn't going to do much for removing excessively strong
signals, such as paging. The single best improvement you can do is to
lose your scanner, and get a better receiver with a better 3rd order
intermod (IMD3) specification. By the nature of the beast, scanners
are highly susceptible to intermod mixes in their front ends.

This is also a problem for many (most?) modern ham HTs, which have
broad-as-a-barn front ends. Their "DC to daylight" reception is both
a feature-advantage and a robustness-disadvantage. Older single-band
radios often have better front end filters.

Yep. Some receivers and scanner at least have tracking filters in the
front end. These have their own collection of problems, such as the
varactors going nonlinear when overloaded and creating a nifty mixer.
However, for most applications, they're much better than a barn door
front end.

There are cavity and crystal notch filters, that will reduce the
signal levels around the paging transmitter frequency, without
affecting the operating frequency (much). Search for crystal VHF
notch filter or cavity VHF notch filter.

http://www.parelectronics.com/amateur.php

I can offer a thumbs-up for the PAR Electronics VHFTN152-158. I had
terrible pager intermod problems with my Yaesu VX-5, whenever I had it
hooked to a "real" antenna (roof, bicycle-mobile flag J-pole, etc.)
rather than a rubber duck.

I have a VX-5 and know what you mean. Totally useless receiver with
an outside antenna. Good to know that the PAR notch filters work. I
may have an application at a repeater site. I usually make my own
notch filters, but I'm tend to get lazy when I'm short on time.

The pager-notch filter eliminated the problem, and as far as I can
tell it hasn't had a significant effect on ham-band receive
sensitivity or transmit power on either 2 meters or 440. I assume I'm
losing some signal and power due to insertion loss but it hasn't been
noticeable.

The Par site claims 0.5dB loss on both 144 and 440Mhz. That's about
5%, which is barely noticeable. No clue what's inside the Par
filters, but from the trimmer, my guess(tm) would be some helical
resonators.

I usually use single port cavities, which are generally useless for
anything except traps, instead of 1/4 wave stubs. I also have a few
adjustable coax sleeves, which work great, but tend to leak a bit.
Lots of ways to build a notch filter.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

"tom" wrote in message
...

And OCFD are not good even at HF if you really understand how they work
and the problems they have because of that.

tom
K0TAR



Tom have you ever compaired the OCF to other antennas at your house ?

I have. I have up an 80 meter dipole and OCF at right angles to each other
at about 50 to 60 feet on each end. There is not much differance in the two
on 80 except in the favored directions.

Also is a 3 element tribander at 60 feet. On 20 and 10 meters there is not
really that much differance on the stateside stations either when the
stations are in the direction the OCF favors. There is a big differance in
the directions that the OCF does not favor as it should be.
If I could only put up a dipole nonrotating antenna, that would still be the
results.

Now granted the OCF will not work all that well above 10 meters, and there
are some low bands such as 15 meters it will not work well as the swr is
very high.

The OCF I am using is a home made Carolina Windom type for 80 meters and
above.

de KU4PT

On Fri, 8 Feb 2013 09:08:47 -0500, "Tom" wrote:

Thanks for the tips

snip

The diamond X-510 has very good reviews,

I cut mine to small pieces and dumped into the garbage bin.

That much for the good reviews.

But you don't want to listen and learn.

w.

I am going to explain it, but only once.
If you talk to the owner of that web site, he will tell you that the designer of the particular model of off center fed dipole that I am talking about is K3CC.
Again, if you call him on the phone, he will explain to you that K3CC holds 27 US patents and is a lot more intelligent then you will ever be.


A off center fed dipole is not a balanced antenna, but exhibits some properities not found in a regular old dipole.

Reguardless of it's length - you can always find someplace where it is resonant. Its SWR is flat as a board on most bands and is below 2:1 most everywhere else with the exception of 15 and 30 meters........

The neatest thing I ever heard was from a old Motorola Technician who told me two important things.
First was that God gave us two ears and only one mouth.
That means we should listen twice as much as we should speak.

Second was that when a manufacturer makes a radio, they make the most important knob the largest knob - hence the tuning knob is the largest knob on the radio.
If you don't like what you hear - you turn the knob.

I was under the impression that this person was a HAM and wanted to talk as well as listen.
Then we got into a discussion about scanners.
Now I am confused.

With any type of communications - if a pager is suspect and it interferes with amateur radio, you can either A - turn the operator of the pager into the FCC for interfering with amateur radio communications - good luck, or you can add filtering.

Even some two meter repeaters operates illegally, because their signals splatter all over other peoples repeaters.. We need to remember that repeaters are not built and owned by the government or industry, but by regular old ham radio operators like you and me.

As far as analog scanners goes, you sure can't beat a Uniden 890XLT...
Even unmodded, it should hold 200 channels, and has a very sensitive receive.

Moving up to a dedicated transceiver - that can be used as a all band scanner, you could purchase a Yaesu 8900 which does everything from 10 meters to 800 MHz.... At about $450 new, and with a slight modification - resistor removal, will transmit 28 - 29 Mhz, 50 - 54 MHz, 140 - 148 Mhz, 430 - 460 Mhz. and will listen everywhere else.

If you don't have a ham license, then just put the microphone away and listen.

It's pretty hard to listen when you are talking, and it is pretty hard to compare one antenna to another when you do not have that particular model of antenna there in front of you and in operation at the same time.
And it is not fair to compare one antenna to another when they are not aimed in the same direction.
Antenna comparisons are made at the same time, within one hour of each other and in the same location and height....

http://www.k3cc.net/

Channel Jumper wrote:

tom;801521 Wrote:
On 2/8/2013 8:24 AM, Channel Jumper wrote:
-
One other antenna - if you had the money and the real estate would be
the High Power - Off Center Fed Dipole - which operates practically
everywhere between 440 MHz and 160 meters - with the exception of 15
and
30 meters.

http://www.angelfire.com/electronic/hypower/-

If you believe that an antenna will operate effectively from 160m to
70cm you are even more ignorant than I previously thought.

And OCFD are not good even at HF if you really understand how they work

and the problems they have because of that.

tom
K0TAR

I am going to explain it, but only once.
If you talk to the owner of that web site, he will tell you that the
designer of the particular model of off center fed dipole that I am
talking about is K3CC.
Again, if you call him on the phone, he will explain to you that K3CC
holds 27 US patents and is a lot more intelligent then you will ever
be.

I hope he is better at designing antennas than at building websites...
Sheesh, what a load of crap. It is still waiting after 5 minutes, and
when I click the "no popups" version I end up at some Google login.

"Rob" wrote in message
...

I hope he is better at designing antennas than at building websites...
Sheesh, what a load of crap. It is still waiting after 5 minutes, and
when I click the "no popups" version I end up at some Google login.

I thought it was just me, but looks like you are having the same problem I
have with that site. I just gave up on trying to get anywhere with it.

I use an OCF lots of times for the low bands, but just do not see it being
very good on 2 meters if designed to start at 160 or 80 meters.
Mine does not appear to be that good even at 6 meters. It might be IF I
find a station in the right direction. My triband for 20,15,10 makes a
beter antenna for 6 than the OCF. I do have 5 elements on 6 with an 18
foot boom to compair it with.

In article ,
Channel Jumper wrote:

Ringo's are nothing more then a over glorified dummy load..

I am sure Dr Reynolds of the University of Washington School of
Electrical Engineering, who designed that antenna for AEA, would
take considerable disagreement, with the above. This design was
Extensively Tested on the UofW's Antenna Range, up on Pigeon Hill, West
Seattle, Washington, which was donated to the UoW, after the Army was
finished with the old Army Communications System site, post WWII.

Channel Jumper sure is a Morooon (Bugs Bunny Definition) and has no
relevant Historical Knowledge.....

Me One who actually KNOEWS the relevant FACTS....

"Me" wrote in message
...
In article ,
Channel Jumper wrote:

Ringo's are nothing more then a over glorified dummy load..

I am sure Dr Reynolds of the University of Washington School of
Electrical Engineering, who designed that antenna for AEA, would
take considerable disagreement, with the above. This design was
Extensively Tested on the UofW's Antenna Range, up on Pigeon Hill, West
Seattle, Washington, which was donated to the UoW, after the Army was
finished with the old Army Communications System site, post WWII.

Channel Jumper sure is a Morooon (Bugs Bunny Definition) and has no
relevant Historical Knowledge.....

Me One who actually KNOEWS the relevant FACTS....

Are you sure AEA had an antenna called Ringo ?

Cushcraft is the only major company I knew of that produced an antenna
called Ringo.

AEA did have several other antennas, the Isopole being one for 2 meters and
some other frequencies.

The origional Ringo for 2 meters was not a very good antenna for most. It
worked , but tended to shoot much of the signal off at high angles. Fine if
in a low area, not so good for the higher areas.
CC also produced some 11 element beams that were a very poor antenna for the
size. I compaired a couple of them with a home built quagi out of the ARRL
handbook and the 8 element quagi was much beter than the 11 element CC.

de KU4PT

On Sat, 09 Feb 2013 10:53:00 -0900, Me wrote:

In article ,
Channel Jumper wrote:

Ringo's are nothing more then a over glorified dummy load..

I am sure Dr Reynolds of the University of Washington School of
Electrical Engineering, who designed that antenna for AEA, would
take considerable disagreement, with the above. This design was
Extensively Tested on the UofW's Antenna Range, up on Pigeon Hill, West
Seattle, Washington, which was donated to the UoW, after the Army was
finished with the old Army Communications System site, post WWII.

Not AEA, but for Cushcraft.

Obituary:
http://community.seattletimes.nwsource.com/archive/?date=19920205&slug=1474034
I don't believe Dr Reynolds designed the Ringo Ranger for Cushcraft
(Now MFJ). The MFJ catalog page claims the Ringo Ranger II was
designed by Lester A. Cushman, W1BX(sk)
http://www.cushcraftamateur.com/Product.php?productid=AR-2
Dr Reynolds did write an article "The 5/8-Wavelength Antenna Mystique"
for the ARRL Antenna Compendium, Volume 1 Pg 101-106, (that seems to
have disappeared from my shelf), which may have created some
confusion.

My take on the Ringo Ranger is that it's a tolerable design, but not
the way it's being built. I've seen far too many cracked SO-239 like
connectors, corroded adjustment screws and elements, crumbling
insulators, crushed mounting tubes, etc. It's major advantage is that
without a molded base transformer, this 5/8 wave or (0.64 wave)
antenna can be cheaply built, and that tunes a tolerable wide
frequency range. Were it built mechanically better, I'm sure it would
have had a better reputation. That lack of a commercial equivalent
also offers a clue as to its quality.



--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558