I have a problem with my rig. There is too much noise main VFO, noise
that looks like somebody is transmitting with bad amp, S-meter jumps
sometimes to +40 dB. The worst is on 70cm, but it is present on all
bands. When I switch to sec. VFO, everything is fine. In the same time,
on the same freq. Main VFO is showing noise.

Any ideas?

Boris
--
Keep 'em Rolling! http://www.mvpa.org/
MVPA: 29718

http://s186.photobucket.com/albums/x51/btudan/

73 de 9A6KTB - Boris

"Boris Tuðan" wrote in message
...
I have a problem with my rig. There is too much noise main VFO, noise
that looks like somebody is transmitting with bad amp, S-meter jumps
sometimes to +40 dB. The worst is on 70cm, but it is present on all
bands. When I switch to sec. VFO, everything is fine. In the same time,
on the same freq. Main VFO is showing noise.

Any ideas?

Boris
--
Keep 'em Rolling! http://www.mvpa.org/
MVPA: 29718

http://s186.photobucket.com/albums/x51/btudan/

73 de 9A6KTB - Boris


Sounds like a transmitter near one of the IF frequencies.

The main and sub have different IF/AF sections.
The Main is multiple conversion with 10.695 MHz. and 455 IFs and multimode
demod that is common to all bands.
The VHF/UHF Sub has a 58 MHz IF that goes straight into its own FM/AM demod.
It is interesting that they used completely different designs for these
packages allowing for advantages and disadvantages of both.

BTW there is a glaring error on page 229 of the original Service Manual.

JB wrote:
Sounds like a transmitter near one of the IF frequencies.

The noise is present even if I remove the antenna...
What can I do? To install external filters?

Boris

--
Keep 'em Rolling! http://www.mvpa.org/
MVPA: 29718

http://s186.photobucket.com/albums/x51/btudan/

73 de 9A6KTB - Boris

"Boris TuÄ'an" wrote in message
...
JB wrote:
Sounds like a transmitter near one of the IF frequencies.

The noise is present even if I remove the antenna...
What can I do? To install external filters?

Boris

--
Keep 'em Rolling! http://www.mvpa.org/
MVPA: 29718

http://s186.photobucket.com/albums/x51/btudan/

73 de 9A6KTB - Boris

It would seem to be something is broken If you pull the antenna off, it
would have to be pretty local. There shouldn't be a problem like that via
the antenna anyway. I would be more inclined to wonder if a switching power
supply had a spurious landing there, but it could also be a noisy IF amp. in
the Main band.

JB wrote:
It would seem to be something is broken If you pull the antenna off, it
would have to be pretty local. There shouldn't be a problem like that via
the antenna anyway. I would be more inclined to wonder if a switching power
supply had a spurious landing there, but it could also be a noisy IF amp. in
the Main band.


TNX for Info, I'll check what's going on during next contest...
--
Keep 'em Rolling! http://www.mvpa.org/
MVPA: 29718

http://s186.photobucket.com/albums/x51/btudan/

73 de 9A6KTB - Boris