On Sat, 27 Aug 2005 23:18:37 +0000, Pete KE9OA wrote about
his ICOM IC-R7100:


Apparently, the reference crystal has drifted down in frequency over
the years.

I have serviced multiple IC-R7000s, IC-R7100As, and other ICOM radios
(e.g., IC-275H) with the same problem. The reference oscillator crystals
in those radios aged after use and shifted frequency. In some cases,
like yours, they go too far off frequency and must be replaced. Check
with ICOM USA for a replacement crystal.

Too bad ICOM didn't burn in the crystals *before* final factory
alignment.

I've not had this problem with the IC-R8500.

--
================================================== =======================
Bob Parnass, AJ9S GNU/Linux User http://parnass.com

I did check the varactor diode voltage and it checked ok..........I wanted
to make sure that the thermistor didn't open up.
Thank you also for your tip, Bob.
The problem did turn out to be the crystal........apparently, some of the
metal from the plates that hold the quartz element itself migrated to the
element, increasing its mass.
It's funny..........on Icom's website they mention that this is an ongoing
problem with the R7000. One would think that they would address this problem
in later iterations.
I did repair the unit. First of all, I replaced that cheap plastic trimmer
with a good microwave unit (Ceratrim). Next, I removed that 1pF shunt
capacitor that was in parallel with the old cap. As it stands right now, I
can tune the 2nd LO up to 1.5kHz above the desired frequency. Not as much
range as I would like, but hopefully, the crystal has done its ageing
process and I won't have to go into the receiver again.
I am going to order a replacement for the reference crystal, just to have on
hand.
Overall, the 7100 is a good receiver. Looking through the service manual, it
appears that all 3 of the mixers are doubly-balanced diode ring mixers that
operate with +10dBm of LO rejection, so the IMD performance should be pretty
decent. It also appears that Icom finally decided to use glass epoxy circuit
boards. I didn't know when they had decided to start doing this, since this
receiver was designed during that "transition time" when there was a mix of
both FR4 and Phenolic being used.
Maybe they finally got tired of repairing those cold solder joints that
would develop over time.
Oh, their quality control................it was pretty funny when I removed
the covers from the shield assemblies and found fingerprints on the inside!
I've got the receiver burning in right now........after another half hour of
running, I will do the final calibration on the 2nd and 1st LOs.
Thanks again for the tips, Mike and Bob!

Pete

"Bob Parnass" wrote in message
news
On Sat, 27 Aug 2005 23:18:37 +0000, Pete KE9OA wrote about
his ICOM IC-R7100:


Apparently, the reference crystal has drifted down in frequency over
the years.

I have serviced multiple IC-R7000s, IC-R7100As, and other ICOM radios
(e.g., IC-275H) with the same problem. The reference oscillator crystals
in those radios aged after use and shifted frequency. In some cases,
like yours, they go too far off frequency and must be replaced. Check
with ICOM USA for a replacement crystal.

Too bad ICOM didn't burn in the crystals *before* final factory
alignment.

I've not had this problem with the IC-R8500.

--
================================================== =======================
Bob Parnass, AJ9S GNU/Linux User http://parnass.com

I still need to check the 3rd LO injection frequency and I do have to adjust
the LSB / USB BFO injection frequencies.
It appears that the main board for this unit is underneath the convertor /
regulator assembly.
The service manual is not clear on how to dissamble the unit. Can anybody
give me any tips on how to get this thing apart? Do the front and rear
panels need to be removed in order to do this?

Pete

"Pete KE9OA" wrote in message
...
I did check the varactor diode voltage and it checked ok..........I wanted
to make sure that the thermistor didn't open up.
Thank you also for your tip, Bob.
The problem did turn out to be the crystal........apparently, some of the
metal from the plates that hold the quartz element itself migrated to the
element, increasing its mass.
It's funny..........on Icom's website they mention that this is an ongoing
problem with the R7000. One would think that they would address this
problem in later iterations.
I did repair the unit. First of all, I replaced that cheap plastic trimmer
with a good microwave unit (Ceratrim). Next, I removed that 1pF shunt
capacitor that was in parallel with the old cap. As it stands right now, I
can tune the 2nd LO up to 1.5kHz above the desired frequency. Not as much
range as I would like, but hopefully, the crystal has done its ageing
process and I won't have to go into the receiver again.
I am going to order a replacement for the reference crystal, just to have
on hand.
Overall, the 7100 is a good receiver. Looking through the service manual,
it appears that all 3 of the mixers are doubly-balanced diode ring mixers
that operate with +10dBm of LO rejection, so the IMD performance should be
pretty decent. It also appears that Icom finally decided to use glass
epoxy circuit boards. I didn't know when they had decided to start doing
this, since this receiver was designed during that "transition time" when
there was a mix of both FR4 and Phenolic being used.
Maybe they finally got tired of repairing those cold solder joints that
would develop over time.
Oh, their quality control................it was pretty funny when I
removed the covers from the shield assemblies and found fingerprints on
the inside!
I've got the receiver burning in right now........after another half hour
of running, I will do the final calibration on the 2nd and 1st LOs.
Thanks again for the tips, Mike and Bob!

Pete

"Bob Parnass" wrote in message
news
On Sat, 27 Aug 2005 23:18:37 +0000, Pete KE9OA wrote about
his ICOM IC-R7100:


Apparently, the reference crystal has drifted down in frequency over
the years.

I have serviced multiple IC-R7000s, IC-R7100As, and other ICOM radios
(e.g., IC-275H) with the same problem. The reference oscillator crystals
in those radios aged after use and shifted frequency. In some cases,
like yours, they go too far off frequency and must be replaced. Check
with ICOM USA for a replacement crystal.

Too bad ICOM didn't burn in the crystals *before* final factory
alignment.

I've not had this problem with the IC-R8500.

--
================================================== =======================
Bob Parnass, AJ9S GNU/Linux User http://parnass.com

I called Icom and the tech told me that I would need to loosen up the front
panel in order to remove the top plate that contains the downconvertor and
the regulator board. This wasn't the case..........it only required the
removal of two screws on the rear panel and two screws at the top front of
the plate assembly. The 10.245MHz LO was only 70Hz low, but the both of the
BFO injection frequencies were at least 1kHz off-frequency so it was good
that I opened up the unit.
I did order the 51.2MHz crystal from Icom and I received it a couple of days
ago..........just in case the present crystal continues to drift.
It was surprising to see glass epoxy boards on the bottom and top units, but
to see that the main receiver board was of a phenolic material. They must
have used the same board from the R-7000........not a bad thing, but I was
surprised.

Pete

"Pete KE9OA" wrote in message
...
I still need to check the 3rd LO injection frequency and I do have to
adjust the LSB / USB BFO injection frequencies.
It appears that the main board for this unit is underneath the convertor /
regulator assembly.
The service manual is not clear on how to dissamble the unit. Can anybody
give me any tips on how to get this thing apart? Do the front and rear
panels need to be removed in order to do this?

Pete

"Pete KE9OA" wrote in message
...
I did check the varactor diode voltage and it checked ok..........I wanted
to make sure that the thermistor didn't open up.
Thank you also for your tip, Bob.
The problem did turn out to be the crystal........apparently, some of the
metal from the plates that hold the quartz element itself migrated to the
element, increasing its mass.
It's funny..........on Icom's website they mention that this is an
ongoing problem with the R7000. One would think that they would address
this problem in later iterations.
I did repair the unit. First of all, I replaced that cheap plastic
trimmer with a good microwave unit (Ceratrim). Next, I removed that 1pF
shunt capacitor that was in parallel with the old cap. As it stands right
now, I can tune the 2nd LO up to 1.5kHz above the desired frequency. Not
as much range as I would like, but hopefully, the crystal has done its
ageing process and I won't have to go into the receiver again.
I am going to order a replacement for the reference crystal, just to have
on hand.
Overall, the 7100 is a good receiver. Looking through the service manual,
it appears that all 3 of the mixers are doubly-balanced diode ring mixers
that operate with +10dBm of LO rejection, so the IMD performance should
be pretty decent. It also appears that Icom finally decided to use glass
epoxy circuit boards. I didn't know when they had decided to start doing
this, since this receiver was designed during that "transition time" when
there was a mix of both FR4 and Phenolic being used.
Maybe they finally got tired of repairing those cold solder joints that
would develop over time.
Oh, their quality control................it was pretty funny when I
removed the covers from the shield assemblies and found fingerprints on
the inside!
I've got the receiver burning in right now........after another half hour
of running, I will do the final calibration on the 2nd and 1st LOs.
Thanks again for the tips, Mike and Bob!

Pete

"Bob Parnass" wrote in message
news
On Sat, 27 Aug 2005 23:18:37 +0000, Pete KE9OA wrote about
his ICOM IC-R7100:


Apparently, the reference crystal has drifted down in frequency over
the years.

I have serviced multiple IC-R7000s, IC-R7100As, and other ICOM radios
(e.g., IC-275H) with the same problem. The reference oscillator
crystals
in those radios aged after use and shifted frequency. In some cases,
like yours, they go too far off frequency and must be replaced. Check
with ICOM USA for a replacement crystal.

Too bad ICOM didn't burn in the crystals *before* final factory
alignment.

I've not had this problem with the IC-R8500.

--
================================================== =======================
Bob Parnass, AJ9S GNU/Linux User
http://parnass.com