Issues with Black Cat amp

[Turbo T]

Thought I'd post and see if anyone has ever seen these issues or know anything about them.

I found on my Black cat amp, if you put the amp in high position, it causes a squeal to be heard from the other parties radio. If you put it on med it works fine. But if you put it on low, it shows no dead key....only shows modulation...in fact in low it works like a sideband radio, where you don't hear anything until that person starts speaking.

Any ideas as to why my amp is doing this?

 

[psycho]

Thought I'd post and see if anyone has ever seen these issues or know anything about them.

I found on my Black cat amp, if you put the amp in high position, it causes a squeal to be heard from the other parties radio. If you put it on med it works fine. But if you put it on low, it shows no dead key....only shows modulation...in fact in low it works like a sideband radio, where you don't hear anything until that person starts speaking.

Any ideas as to why my amp is doing this?

For the low stage, maybe you aren't putting enough DK watts into it or the low stage resistor could be bad. High stage squeal, not a clue. The BC amps are junk with some quality issues.
Yank it out of there and put the Bimbo in, problem solved.

 

[Atlasta]

I had a similar issue with my 10-tube Phantom. Low and medium were fine but it would start squealing (self-oscillating,really) on the high side or when I turned the mic gain up past bare minimum.

Turned out that some RF was getting in through the mic cord. I snapped a ferrell (sp?) coil around the cord right where it plugged into the radio - problem solved!

If I recall correctly the Black Cats were designed to run as a modulator on the low side- but I may be wrong.

 

[unit_399]

Which model Black Cat do you have???

 

[psycho]

Which model Black Cat do you have???

He posted pictures a couple of weeks ago, it was a Blackcat 300 which is just a bad Palomar clone.
2x1446

Here is a picture of this gem, not the actual one! There is no fan on TTs.

 

[TonyV225]

if you put it on low, it shows no dead key....only shows modulation...in fact in low it works like a sideband radio, where you don't hear anything until that person starts speaking.

Any ideas as to why my amp is doing this?

Thats actually kind of cool its working like a modulator and would save on transistor life and Im guessing it has the SD-1446 transistors in it. As far as why its sqealing Im going to say its getting RF feeding back into it from somewhere. Ive seen a few of these be finicy as far as stray RF and acting up Try running an extra ground connected to a screw on the chassis or use a PL-259 -- SO-239 lightning arrestor adaptor with the ground screw lug on it with an extra grong wire ran to the chassiis of the car or ground in the house.

http://rover.ebay.com/rover/1/711-5...0001&campid=5336136228&icep_item=190697143604

 

[Turbo T]

For the low stage, maybe you aren't putting enough DK watts into it or the low stage resistor could be bad. High stage squeal, not a clue. The BC amps are junk with some quality issues.
Yank it out of there and put the Bimbo in, problem solved.

Funny thing is my Bimbo also squeals. When in PEP power that is. Put it in RMS and you get the same effects as the Black Cat on low.

 

[Robb]

Funny thing is my Bimbo also squeals. When in PEP power that is. Put it in RMS and you get the same effects as the Black Cat on low.

So; you might be talking about two distinctly different problems here. One, is that the RADIO has a feedback issue for as yet an undetermined reason. And second, that the AMP is having a problem with either its biasing circuit or one of the finals has failed.

This is just my best guess at this point.
Still learning how to work on radios . . .

 

[Zman]

He posted pictures a couple of weeks ago, it was a Blackcat 300 which is just a bad Palomar clone.
2x1446

It is a rip off using the cat logos that Wawasee Electronics had a copyright on, LOL.

 

[Turbo T]

I tried putting a Rat Shack choke on the mic cable at the plug. Still squeals. Guess I need to dig a little deeper?

 

[9C1Driver]

He posted pictures a couple of weeks ago, it was a Blackcat 300 which is just a bad Palomar clone.
2x1446

It is a rip off using the cat logos that Wawasee Electronics had a copyright on, LOL.

I agree but since they are long out of business I doubt they will mind. Same goes for the real Palomar name.

 

[Shockwave]

If the radio and the amplifier are powered from the same wire or power supply, consider that the RF feedback may be through the DC power line. In this case you could try using the Radio Shack RF choke on the DC power wire right at the back of the radio. The missing carrier on low power is just a drive issue that is corrected by using medium or high power.