MRF 492
 

Picked up a home built linear with 2 of the above pills. It doesn't work
and I've replaced both pills. Obviously its hard to troubleshoot it
without a schematic but just on the off chance someone may have
experience with something akin to this what else should i look for?
ground appears ok as well as ant center conductor isn't shorted to ground.

MRF 492
 

On Thu, 22 Dec 2005 20:07:04 -0500, jim wrote:

Picked up a home built linear with 2 of the above pills. It doesn't work
and I've replaced both pills. Obviously its hard to troubleshoot it
without a schematic but just on the off chance someone may have
experience with something akin to this what else should i look for?
ground appears ok as well as ant center conductor isn't shorted to ground.


Any relays in it?

Can you draw a schematic and try to go from there?

Vinnie S.

MRF 492
 

jim wrote:
Picked up a home built linear with 2 of the above pills. It doesn't work
and I've replaced both pills. Obviously its hard to troubleshoot it
without a schematic but just on the off chance someone may have
experience with something akin to this what else should i look for?
ground appears ok as well as ant center conductor isn't shorted to ground.


Those are VHF rated transistors. Does it have the traditional
BB matching xformers or is it TRF circuits?

MRF 492
 

Scott in Baltimore wrote:
jim wrote:

Picked up a home built linear with 2 of the above pills. It doesn't work
and I've replaced both pills. Obviously its hard to troubleshoot it
without a schematic but just on the off chance someone may have
experience with something akin to this what else should i look for?
ground appears ok as well as ant center conductor isn't shorted to
ground.



Those are VHF rated transistors. Does it have the traditional
BB matching xformers or is it TRF circuits?
no xformers on the board. Excuse my ignorance but what is a TRF circuit?

MRF 492
 

Vinnie S. wrote:

On Thu, 22 Dec 2005 20:07:04 -0500, jim wrote:


Picked up a home built linear with 2 of the above pills. It doesn't work
and I've replaced both pills. Obviously its hard to troubleshoot it
without a schematic but just on the off chance someone may have
experience with something akin to this what else should i look for?
ground appears ok as well as ant center conductor isn't shorted to ground.



Any relays in it?

Can you draw a schematic and try to go from there?

Vinnie S.
Yeah there is a relay. I thought about that but there isn't any
identifying marks to tell me what it is. I cant come up with a schematic
but when i get my Sony Mavica working I will post a pic on my web site.
Sorry to be so oblique but this thing is a mystery.
BTW what is the Jets priority in the draft? Trade down and get more picks?

MRF 492
 

Those are VHF rated transistors. Does it have the traditional
BB matching xformers or is it TRF circuits?

no xformers on the board. Excuse my ignorance but what is a TRF circuit?

Tuned Radio Frequency.

The input and output circuits are fixed in one small range.
Capacitors and inductors only have certain values at certain
frequencies. At others, the match is very poor.

Maybe the amp is designed for another frequency.

Amps with broadband matching transformers will work over
serveral decades of range. Most active devices will output
more at lower frequencies.

MRF 492
 

Scott in Baltimore wrote:

Those are VHF rated transistors. Does it have the traditional
BB matching xformers or is it TRF circuits?


no xformers on the board. Excuse my ignorance but what is a TRF circuit?


Tuned Radio Frequency.

The input and output circuits are fixed in one small range.
Capacitors and inductors only have certain values at certain
frequencies. At others, the match is very poor.

Maybe the amp is designed for another frequency.

Amps with broadband matching transformers will work over
serveral decades of range. Most active devices will output
more at lower frequencies.
It was designed for 11 meters as I have used it with great success. It
would xmit the roger beep but no audio.

MRF 492
 

On Thu, 22 Dec 2005 21:17:07 -0500, jim wrote:

Vinnie S. wrote:

On Thu, 22 Dec 2005 20:07:04 -0500, jim wrote:


Picked up a home built linear with 2 of the above pills. It doesn't work
and I've replaced both pills. Obviously its hard to troubleshoot it
without a schematic but just on the off chance someone may have
experience with something akin to this what else should i look for?
ground appears ok as well as ant center conductor isn't shorted to ground.



Any relays in it?

Can you draw a schematic and try to go from there?

Vinnie S.
Yeah there is a relay. I thought about that but there isn't any
identifying marks to tell me what it is. I cant come up with a schematic
but when i get my Sony Mavica working I will post a pic on my web site.
Sorry to be so oblique but this thing is a mystery.
BTW what is the Jets priority in the draft? Trade down and get more picks?


If they can't get Bush, trade down. I would dump Abraham for more picks. And get
Jimmy Johnson to coach.


Vinnie S.

MRF 492
 

"jim" wrote in message
...
Scott in Baltimore wrote:

Those are VHF rated transistors. Does it have the traditional
BB matching xformers or is it TRF circuits?


no xformers on the board. Excuse my ignorance but what is a TRF circuit?


Tuned Radio Frequency.

The input and output circuits are fixed in one small range.
Capacitors and inductors only have certain values at certain
frequencies. At others, the match is very poor.

Maybe the amp is designed for another frequency.

Amps with broadband matching transformers will work over
serveral decades of range. Most active devices will output
more at lower frequencies.
It was designed for 11 meters as I have used it with great success. It
would xmit the roger beep but no audio.

If it transmits the roger beep then its not the amp. Sounds like the radio
has a modulation problem.

MRF 492
 

On Thu, 22 Dec 2005 20:07:04 -0500, jim
wrote:

Picked up a home built linear with 2 of the above pills. It doesn't work
and I've replaced both pills. Obviously its hard to troubleshoot it
without a schematic but just on the off chance someone may have
experience with something akin to this what else should i look for?
ground appears ok as well as ant center conductor isn't shorted to ground.

492's ? Did you try 28 volts?