-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
Palomar 225 Delay way to long
- Thread starter NoCorn
- Start date
A 20 second delay would suggest something is wrong there because that is not even close to what most auto delay amps have. An off hand guess would be either a component that controls the delay is failing or the amp might have an impedance mismatch causing it to not want to un-key. Some of those class C Palomar amps can act funny when the jumper is too short as well. Good luck.
The watts drop off as soon as I unkey. Not sure what’s going on. Probably a component like you said.
sounds like the amp might be oscillating.
how does it act with an AM signal?
does this amp have an AM/SSB switch or is it auto SSB delay (meaning the delay is there on AM and SSB).
what radio and how many watts are you feeding it?
what is the SWR going IN to the amp?
to measure this, connect the SWR meter in between the radio and the input of the amp, and use AM mode unmodulated, with the amp ON.
best to use a dummy load on the output of the amp, but if you don't have one, just use your antenna as long at it's SWR is 1.5 or less.
LC
how does it act with an AM signal?
does this amp have an AM/SSB switch or is it auto SSB delay (meaning the delay is there on AM and SSB).
what radio and how many watts are you feeding it?
what is the SWR going IN to the amp?
to measure this, connect the SWR meter in between the radio and the input of the amp, and use AM mode unmodulated, with the amp ON.
best to use a dummy load on the output of the amp, but if you don't have one, just use your antenna as long at it's SWR is 1.5 or less.
LC
Has automatic side band, acts fine on Am, 1.5 watt dead key, in is 1.2 out is 1.3 SWR.
IF this looks like part of your board...
You have two caps, Might want to check the caps legs, one may have touched the case, this may cause the cap to short and even blow the trace leading to it, it could explain the long delay - the transistor stays on while the transistor itself pulls the current off the cap - holding the relay closed (TX mode) until the cap is drained - but is it "welded" or touched the case (below on some of the foil traces underneath it's dual-sided) damaging the cap? If so it can damage the board and give you quirky SSB results.
But, if the SSB side if a diode is open - the bias gets held up and the amp runs like a weak oscillator - it's high gain parts just make the thing ring with a weak and very wide noise factor - you could hear on a monitor radio or even a shortwave receiver - the self-resonance and the SSB delay - the RF-sense keeps the cap and the extra bias on and lets the amp ring to death - eventually if not fixed, the amp will self -destruct. .
You have two caps, Might want to check the caps legs, one may have touched the case, this may cause the cap to short and even blow the trace leading to it, it could explain the long delay - the transistor stays on while the transistor itself pulls the current off the cap - holding the relay closed (TX mode) until the cap is drained - but is it "welded" or touched the case (below on some of the foil traces underneath it's dual-sided) damaging the cap? If so it can damage the board and give you quirky SSB results.
But, if the SSB side if a diode is open - the bias gets held up and the amp runs like a weak oscillator - it's high gain parts just make the thing ring with a weak and very wide noise factor - you could hear on a monitor radio or even a shortwave receiver - the self-resonance and the SSB delay - the RF-sense keeps the cap and the extra bias on and lets the amp ring to death - eventually if not fixed, the amp will self -destruct. .
can't seem to find a schematic online to tell you which cap is the SSB delay cap, so if you can take a pic of the inside, that would help.
i do think that the relay might just be hanging up since the delay is sooooo long.
how many watts PEP are you feeding it on SSB?
it shouldn't be more than about 15 watts PEP.
LC
i do think that the relay might just be hanging up since the delay is sooooo long.
how many watts PEP are you feeding it on SSB?
it shouldn't be more than about 15 watts PEP.
LC
Hmmm...If bias is sent along with the RF on the relay (instead of using two relays to keep DC and RF currents separate) that can hold a relay from releasing (bias too high) because the RF the amp has circulating inside it - can keep the RF-detect switch circulating enough current to keep the relay in TX
Or smoked a 10-ohm resistor - the other one looking for marshmallows to go with the molten solder forming under its legs.
Bias is strange that way - the PN on the NPN junctions at the Base lead and easily form a rectified power and if a resistor or two is open, the imbalance can also generate the circulating "DC rectified" RF component a relay can't simply disconnect from.
Or smoked a 10-ohm resistor - the other one looking for marshmallows to go with the molten solder forming under its legs.
Bias is strange that way - the PN on the NPN junctions at the Base lead and easily form a rectified power and if a resistor or two is open, the imbalance can also generate the circulating "DC rectified" RF component a relay can't simply disconnect from.