Hi, I have got a problem when transmitting on bands from 18MHz up.
Signal is distorted (on all power levels) and there is something like
"self-generations" - also on AM

Any ideas?

MAc
mrn

On Thu, 21 Feb 2008 01:33:53 +0100, MAc
wrote:

Hi, I have got a problem when transmitting on bands from 18MHz up.
Signal is distorted (on all power levels) and there is something like
"self-generations" - also on AM

Any ideas?

MAc
mrn


Yes most likely the VCO trimmer caps are in trouble. You may get some
life out of them doing a HPL alignment where you just tune the 4 VCO
trimmers. If not then they require replacing and generally all 4 are
done at that time.

Gary K8IZ

Gary P. Fiber pisze:

Yes most likely the VCO trimmer caps are in trouble.


Even if RX is OK?

Of course thanks for help. I know, that work with trimmers is waiting
for me....

MAc
sp9mrn

additional info:

on ssb i hear my distorted voice in headphones when transmitting
(monitor is off)

MAc

MAc wrote:

additional info:

on ssb i hear my distorted voice in headphones when transmitting
(monitor is off)

This gets me thinking about grounding, how good, how old, how far, etc.
is yours? I had similar problems feeding a long wire on 15m and up when
grounded with a 2" wide copper strap to a 10' driven ground rod. Once I
shortened the strap all the problems went away.

Good luck!
- Galen, W8LNA

additional info:

on ssb i hear my distorted voice in headphones when transmitting (monitor is
off)

MAc

In my experience, I had somewhat the same problem. Once the
operating chip starts to fail, you will loose bands one by one starting
from the highest band like 10 meters. Then you will loose 15 meters,
20 meters, then 40 meters one by one. Send it to a authoized ICOM
repaid center and they will restore the missing bands as I did.
Later found a hame in Italy that was marketing a new ramboard that
would last forever and you would remobe the old ramboard and install
his. After that you cant loose the operating system. You could loose
the "memory" chnls as they are a seperate entity and require a good
backup long lasting to retain the "memory" chnls only. So far I have
had no further loss of bands. Nor have I lost any memory channels and its
been about 10 years now. I dont remember the Italians name but think
it was Bernardo and he was a ham operator and marketed those rplacement
RAM boards world wide. Stictly for the ICOM751.
Joe KH6JF

Joseph Fenn pisze:

In my experience, I had somewhat the same problem. Once the
operating chip starts to fail, you will loose bands one by one starting
from the highest band like 10 meters. Then you will loose 15 meters,
20 meters, then 40 meters one by one.

brr, terrible future

Send it to a authoized ICOM
repaid center and they will restore the missing bands as I did.

The problem is, that I'm in Poland. The cost of sending 50pounds twice
across the ocean is higher, then value of IC761 :-)
So I have to do it myself.



Later found a hame in Italy that was marketing a new ramboard that
would last forever and you would remobe the old ramboard and install
his.

I'll look for him

But - In IC761 maual they wrote, that the memory (known "battery
problem) does not affect 761 - only 751.
On the other hand - many hams told me, that 761 has THE SAME problem
like 751.

I dont know what to think

MAc
sp9mrn

Still graeat thanks for any possible help and ideas

Joseph Fenn pisze:

In my experience, I had somewhat the same problem. Once the
operating chip starts to fail, you will loose bands one by one starting
from the highest band like 10 meters. Then you will loose 15 meters,
20 meters, then 40 meters one by one.

brr, terrible future

Send it to a authoized ICOM
repaid center and they will restore the missing bands as I did.

The problem is, that I'm in Poland. The cost of sending 50pounds twice
across the ocean is higher, then value of IC761 :-)
So I have to do it myself.



Later found a hame in Italy that was marketing a new ramboard that
would last forever and you would remobe the old ramboard and install
his.

I'll look for him

But - In IC761 maual they wrote, that the memory (known "battery
problem) does not affect 761 - only 751.
On the other hand - many hams told me, that 761 has THE SAME problem
like 751.

I dont know what to think

MAc
sp9mrn

Still graeat thanks for any possible help and ideas

Joseph Fenn pisze:

In my experience, I had somewhat the same problem. Once the
operating chip starts to fail, you will loose bands one by one starting
from the highest band like 10 meters. Then you will loose 15 meters,
20 meters, then 40 meters one by one.

brr, terrible future

Send it to a authoized ICOM
repaid center and they will restore the missing bands as I did.

The problem is, that I'm in Poland. The cost of sending 50pounds twice
across the ocean is higher, then value of IC761 :-)
So I have to do it myself.



Later found a hame in Italy that was marketing a new ramboard that
would last forever and you would remobe the old ramboard and install
his.

I'll look for him

But - In IC761 maual they wrote, that the memory (known "battery
problem) does not affect 761 - only 751.
On the other hand - many hams told me, that 761 has THE SAME problem
like 751.

I dont know what to think

MAc
sp9mrn

Still graeat thanks for any possible help and ideas

On Thu, 21 Feb 2008 11:16:12 +0100, MAc
wrote:

Gary P. Fiber pisze:

Yes most likely the VCO trimmer caps are in trouble.


Even if RX is OK?

Of course thanks for help. I know, that work with trimmers is waiting
for me....

MAc
sp9mrn

The above 18 MHz made me think of the trimmer capacitors. Are you
using the ACC 1 jack? anything attached to that jack? Could also be
RFI getting into that jack for any wires connected to it.

If the trimmers the distortion can show up on either TX or RX but
usually it shows in RX first.

log onto www.icomamerica.com under support, then knowledge base,
choose amateur, then HF then the IC-761 from the radio choices. Then
do not specify an article. You should get a whole listing of more
commonly found faults found over the years with the IC-761.

Gary K8IZ