Palomar Magnum TX2250HD - Help

[Robbo]

Hi all,
I have a Palomar Magnum TX2250HD amp with a problem.
It stays on Tx after the mic button is released and some of the components get very hot. (resistors)

If you have any ideas, please let me know.

Also, I would like a schematic diagram for this amp, if anybody has one could I have a copy please?

73
Rob

 

[9C1Driver]

Probably needs a new keying transistor or relay. Not sure how those are set up.This place has many different amp diagrams.

http://www.cbtricks.com/Amp/index.htm

 

[Robbo]

Probably needs a new keying transistor or relay. Not sure how those are set up.This place has many different amp diagrams.

http://www.cbtricks.com/Amp/index.htm

Hi 9C1Driver,
Thanks for the info, but could not find any diagrams for this amp.
Will keep looking.
Cheers
Rob

 

[kopcicle]

There are few designs repeated over and over again with many different names.
photos would help.

 

[Robbo]

There are few designs repeated over and over again with many different names.
photos would help.

Hi,
I have attached 3 photo's, hope it helps.

Cheers
Rob

 

[9C1Driver]

Nice. Those were also made under the Bulletproof name. I have one that has two 1446 finals, I love the variable SSB delay on the back.

 

[*Brett*]

Hi all,
I have a Palomar Magnum TX2250HD amp with a problem.
It stays on Tx after the mic button is released and some of the components get very hot. (resistors)

If you have any ideas, please let me know.

Also, I would like a schematic diagram for this amp, if anybody has one could I have a copy please?

73
Rob

Hi Rob,
I just found your post, I hope you found a schematic, If not here you go;

Cheers
Brett 73

 

[Big Kahuna]

What length jumper between radio and amp are you using? Once or twice when using a short piece (1ft-2ft) cheaper coax between radio and amp I’ve run into a issue where the amp wouldn’t unkey.

 

[*Brett*]

Hi Big Kahuna, I just checked a few of the jumper cables, that I have. All of them are commercially made, (bought ones) although from different suppliers, they are all 3 feet long (90 centimeters). You could also try wrapping a few turns of the coax around FT240-43 Toroid which will help with stray RF

 

[Big Kahuna]

Hi Big Kahuna, I just checked a few of the jumper cables, that I have. All of them are commercially made, (bought ones) although from different suppliers, they are all 3 feet long (90 centimeters). You could also try wrapping a few turns of the coax around FT240-43 Toroid which will help with stray RF

Yeah I've known it to happen even with 3 foot jumpers on some of the "CB amps" with the RF causing the amp to hang on TX. Just thought it's something you might want to check. Have you tried turning SSB delay all the way down and see if it happens? Does it do it with the mic gain at zero, or only when you're talking?

 

[Shockwave]

The amplifier is oscillating.

 

[Crusher]

What radio are you using to drive this?

 

[Handy Andy]

Have you tried turning SSB delay all the way down and see if it happens?

That makes 2 of us...

A dirty switch or open wiper arm in the pot for SSB delay - can make a nice antenna to pick up RF and keep reinjecting RF signal to keep it in TX...

May not be the frequency you were keying on - (first clue) but it will "resonate" at a natural frequency - that means the amp needs some help.

Those front and rear panels use a "slide in" rail for those screws and are anodized aluminum, - means they insulate, so those pills are possibly the only ground that the amp really has - might be prudent to put some TLC into the screws and hardware. Even carefully undo the panels to gain access to the pills bottoms, that area takes in all their heat - and if it's not tight to the sink above (behind the pills flanges) it can add "things" to this problem you don't need.