I recently acquired a "dead" Ft-990.

I got the receiver running and found I had a bad T/R relay, got that
replaced, now I have 100++ power out on all bands no matter where the RF Pwr
knob is set. I have come a long way from a dead transceiver, but the rig is
still unusable as is since the output cannot be adjusted. I did see a
voltage change from ~-6 volts to about +.3 volts at a test point shown in
the service manual. I thought I'd drop a quick note in here to see if
someone may have run into a similar issue with the 990 in the past. I THINK
the problem is on the RF card, but am not sure. The service manual is great
for schematics and part numbers, but is seriously lacking in theory.

Anyhow, any help / suggestions would be great. remove the "spam" to email
me directly, if you like.

Ron E.
W0IFL

When I worked at Icom we saw a few that acted like your Yaesu does. On
the Icom's it was almost always the Power Amplifier was oscillating.
When that happens no power control adjustment is going to help. Some
of the times it was a transistor in the receiver switching circuit
that was causing the oscillation to happen.

Just a thought, I know Icom and Yaesu are not the same but I would
suspect circuit designs are not that dissimilar.




On Wed, 19 Nov 2003 18:47:06 GMT, "RonE" wrote:

I recently acquired a "dead" Ft-990.

I got the receiver running and found I had a bad T/R relay, got that
replaced, now I have 100++ power out on all bands no matter where the RF Pwr
knob is set. I have come a long way from a dead transceiver, but the rig is
still unusable as is since the output cannot be adjusted. I did see a
voltage change from ~-6 volts to about +.3 volts at a test point shown in
the service manual. I thought I'd drop a quick note in here to see if
someone may have run into a similar issue with the 990 in the past. I THINK
the problem is on the RF card, but am not sure. The service manual is great
for schematics and part numbers, but is seriously lacking in theory.

Anyhow, any help / suggestions would be great. remove the "spam" to email
me directly, if you like.

Ron E.
W0IFL



Gary K8IZ
Washington State Resident
Registered Linux User # 312991

When I worked at Icom we saw a few that acted like your Yaesu does. On
the Icom's it was almost always the Power Amplifier was oscillating.
When that happens no power control adjustment is going to help. Some
of the times it was a transistor in the receiver switching circuit
that was causing the oscillation to happen.

Just a thought, I know Icom and Yaesu are not the same but I would
suspect circuit designs are not that dissimilar.




On Wed, 19 Nov 2003 18:47:06 GMT, "RonE" wrote:

I recently acquired a "dead" Ft-990.

I got the receiver running and found I had a bad T/R relay, got that
replaced, now I have 100++ power out on all bands no matter where the RF Pwr
knob is set. I have come a long way from a dead transceiver, but the rig is
still unusable as is since the output cannot be adjusted. I did see a
voltage change from ~-6 volts to about +.3 volts at a test point shown in
the service manual. I thought I'd drop a quick note in here to see if
someone may have run into a similar issue with the 990 in the past. I THINK
the problem is on the RF card, but am not sure. The service manual is great
for schematics and part numbers, but is seriously lacking in theory.

Anyhow, any help / suggestions would be great. remove the "spam" to email
me directly, if you like.

Ron E.
W0IFL



Gary K8IZ
Washington State Resident
Registered Linux User # 312991

Thanks Gary,
I never even considered that. I did have to replace the T/R relay, it was
stuck in receive. I scratched my head over that for a while... 20Amp current
draw, and NO output.. Anyhow, got that replaced. Maybe the transistor that
drives that relay needs replaced as well..

Ron E.
W0IFL
--

"Gary P. Fiber" wrote in message
...
When I worked at Icom we saw a few that acted like your Yaesu does. On
the Icom's it was almost always the Power Amplifier was oscillating.
When that happens no power control adjustment is going to help. Some
of the times it was a transistor in the receiver switching circuit
that was causing the oscillation to happen.

Just a thought, I know Icom and Yaesu are not the same but I would
suspect circuit designs are not that dissimilar.




On Wed, 19 Nov 2003 18:47:06 GMT, "RonE" wrote:

I recently acquired a "dead" Ft-990.

I got the receiver running and found I had a bad T/R relay, got that
replaced, now I have 100++ power out on all bands no matter where the RF
Pwr
knob is set. I have come a long way from a dead transceiver, but the rig
is
still unusable as is since the output cannot be adjusted. I did see a
voltage change from ~-6 volts to about +.3 volts at a test point shown in
the service manual. I thought I'd drop a quick note in here to see if
someone may have run into a similar issue with the 990 in the past. I
THINK
the problem is on the RF card, but am not sure. The service manual is
great
for schematics and part numbers, but is seriously lacking in theory.

Anyhow, any help / suggestions would be great. remove the "spam" to
email
me directly, if you like.

Ron E.
W0IFL



Gary K8IZ
Washington State Resident
Registered Linux User # 312991

Thanks Gary,
I never even considered that. I did have to replace the T/R relay, it was
stuck in receive. I scratched my head over that for a while... 20Amp current
draw, and NO output.. Anyhow, got that replaced. Maybe the transistor that
drives that relay needs replaced as well..

Ron E.
W0IFL
--

"Gary P. Fiber" wrote in message
...
When I worked at Icom we saw a few that acted like your Yaesu does. On
the Icom's it was almost always the Power Amplifier was oscillating.
When that happens no power control adjustment is going to help. Some
of the times it was a transistor in the receiver switching circuit
that was causing the oscillation to happen.

Just a thought, I know Icom and Yaesu are not the same but I would
suspect circuit designs are not that dissimilar.




On Wed, 19 Nov 2003 18:47:06 GMT, "RonE" wrote:

I recently acquired a "dead" Ft-990.

I got the receiver running and found I had a bad T/R relay, got that
replaced, now I have 100++ power out on all bands no matter where the RF
Pwr
knob is set. I have come a long way from a dead transceiver, but the rig
is
still unusable as is since the output cannot be adjusted. I did see a
voltage change from ~-6 volts to about +.3 volts at a test point shown in
the service manual. I thought I'd drop a quick note in here to see if
someone may have run into a similar issue with the 990 in the past. I
THINK
the problem is on the RF card, but am not sure. The service manual is
great
for schematics and part numbers, but is seriously lacking in theory.

Anyhow, any help / suggestions would be great. remove the "spam" to
email
me directly, if you like.

Ron E.
W0IFL



Gary K8IZ
Washington State Resident
Registered Linux User # 312991

The -6 is the clue. It is a reference for the power control circuit and when
it goes away so does the control. At least on Kenwoods and Icoms.

--
Clif Holland, KA5IPF
AVVid
Authorized Kenwood and Icom Service Center
816 W Shady Grove Rd
Irving, TX 75060

www.avvid.com

1-800-214-5779
972-870-0630 (Local)
"RonE" wrote in message
...
Thanks Gary,
I never even considered that. I did have to replace the T/R relay, it was
stuck in receive. I scratched my head over that for a while... 20Amp
current
draw, and NO output.. Anyhow, got that replaced. Maybe the transistor
that
drives that relay needs replaced as well..

Ron E.
W0IFL
--

"Gary P. Fiber" wrote in message
...
When I worked at Icom we saw a few that acted like your Yaesu does. On
the Icom's it was almost always the Power Amplifier was oscillating.
When that happens no power control adjustment is going to help. Some
of the times it was a transistor in the receiver switching circuit
that was causing the oscillation to happen.

Just a thought, I know Icom and Yaesu are not the same but I would
suspect circuit designs are not that dissimilar.




On Wed, 19 Nov 2003 18:47:06 GMT, "RonE" wrote:

I recently acquired a "dead" Ft-990.

I got the receiver running and found I had a bad T/R relay, got that
replaced, now I have 100++ power out on all bands no matter where the
RF
Pwr
knob is set. I have come a long way from a dead transceiver, but the
rig
is
still unusable as is since the output cannot be adjusted. I did see a
voltage change from ~-6 volts to about +.3 volts at a test point shown
in
the service manual. I thought I'd drop a quick note in here to see if
someone may have run into a similar issue with the 990 in the past. I
THINK
the problem is on the RF card, but am not sure. The service manual is
great
for schematics and part numbers, but is seriously lacking in theory.

Anyhow, any help / suggestions would be great. remove the "spam" to
email
me directly, if you like.

Ron E.
W0IFL



Gary K8IZ
Washington State Resident
Registered Linux User # 312991

The -6 is the clue. It is a reference for the power control circuit and when
it goes away so does the control. At least on Kenwoods and Icoms.

--
Clif Holland, KA5IPF
AVVid
Authorized Kenwood and Icom Service Center
816 W Shady Grove Rd
Irving, TX 75060

www.avvid.com

1-800-214-5779
972-870-0630 (Local)
"RonE" wrote in message
...
Thanks Gary,
I never even considered that. I did have to replace the T/R relay, it was
stuck in receive. I scratched my head over that for a while... 20Amp
current
draw, and NO output.. Anyhow, got that replaced. Maybe the transistor
that
drives that relay needs replaced as well..

Ron E.
W0IFL
--

"Gary P. Fiber" wrote in message
...
When I worked at Icom we saw a few that acted like your Yaesu does. On
the Icom's it was almost always the Power Amplifier was oscillating.
When that happens no power control adjustment is going to help. Some
of the times it was a transistor in the receiver switching circuit
that was causing the oscillation to happen.

Just a thought, I know Icom and Yaesu are not the same but I would
suspect circuit designs are not that dissimilar.




On Wed, 19 Nov 2003 18:47:06 GMT, "RonE" wrote:

I recently acquired a "dead" Ft-990.

I got the receiver running and found I had a bad T/R relay, got that
replaced, now I have 100++ power out on all bands no matter where the
RF
Pwr
knob is set. I have come a long way from a dead transceiver, but the
rig
is
still unusable as is since the output cannot be adjusted. I did see a
voltage change from ~-6 volts to about +.3 volts at a test point shown
in
the service manual. I thought I'd drop a quick note in here to see if
someone may have run into a similar issue with the 990 in the past. I
THINK
the problem is on the RF card, but am not sure. The service manual is
great
for schematics and part numbers, but is seriously lacking in theory.

Anyhow, any help / suggestions would be great. remove the "spam" to
email
me directly, if you like.

Ron E.
W0IFL



Gary K8IZ
Washington State Resident
Registered Linux User # 312991