Amp help

[ShadowDelaware]

I sold a guy an amplifier and I believe he connected his coax in reverse. I took back the amp and am curious how I can test for this or if anyone knows what the consequences of thos would be to the amp.

 

[Shadetree Mechanic]

If he had it backwards, it might have damaged the final in his radio. Might not have hurt the amp. Pop the cover and see if anything looks burnt. Maybe hook it up and see what it does?

 

[RADIO51]

I did that once when i was young, i started freaking out. It was only two very fast keys. I got lucky, it didnt hurt anything and the box was fine. Start with visual inspection, if all looks good and you have a lack of test equipment, hook it up and key it. Short quick keys and see what happens.

 

[loosecannon]

i dont know that this would have damaged anything.

someone correct me if im wrong here, but it would seem to me that if the input of the amp was connected to the antenna then there would be no RF present and the amp would not have produced any RF power.
LC

 

[Shadetree Mechanic]

i dont know that this would have damaged anything.

someone correct me if im wrong here, but it would seem to me that if the input of the amp was connected to the antenna then there would be no RF present and the amp would not have produced any RF power.
LC

I was thinking if the amplifier keyed, it might go into oscillations. So the keying relay would trigger, but as soon as it did, the RF would be gone so it would unkey. Maybe the relay would chatter?

 

[loosecannon]

yeah Shadetree i just don't know.

I mean, technically you are trying to feed RF into the collectors of the transistors when you hook it up that way so maybe there is a chance of damage.
LC

 

[nomadradio]

As a general rule, what happens when you do this is to make the relay "chatter" or buzz.

When the relay closes, it cuts off the RF drive from the radio to the keying circuit. The relay will "click" and remain energized only until the contacts change over. This removes the radio's drive RF from the RF sensing circuit, because it was traveling through the relay's receive side. This causes the relay to drop back to receive mode. But not for long, because this reconnects the radio's RF through the relay's standby side to the sensing circuit and the cycle repeats. Migh buzz, might "chatter" several times a second.

Can't see how the amplifier would be damaged this way. The radio might not be as forgiving.

73

 

[Critter98]

I suspect that is how I fried my SWR meter.

 

[nomadradio]

Fried?

As in blown diodes?

73

 

[Critter98]

To be honest, I don't know what is wrong with it. I tested the diodes (Germanic) & replaced one. Replaced 2 capacitors, couldn't see any burned spots. It just stopped working.

 

[nomadradio]

Did you put the meter on ohms and put the leads onto the meter's terminals. One way it will peg to the left. Reverse the leads and it will usually peg to the right.

If the coil in the meter is fried, it won't do anything. And the ohmeter won't show continuity.

73

 

[Critter98]

Yes I checked that out and the needle swings.