I have my brothers Creme and tan D&A Phantom it all of of sudden has no output I have checked tubes, power diodes, power capacitors all ok. All relays are switching and I have correct voltage at top of tubes 850 on high. When keying amp up no output and meters on amp also show no output I have cleaned relays also. Any suggestions on what to check next would be appreciated. Thank You Jimbo165
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Phantom no output
- Thread starter Jimbo165
- Start date
Phantom no output
Amp has no keying tube. I key up radio and amp keys relays not sure about a blocking capacitor I have not checked that where is is located? I have CB tricks schematic of amp but being a novice and still learning I need help for sure. Cannot see anything that looks burnt either. Thanks Jimbo165
Amp has no keying tube. I key up radio and amp keys relays not sure about a blocking capacitor I have not checked that where is is located? I have CB tricks schematic of amp but being a novice and still learning I need help for sure. Cannot see anything that looks burnt either. Thanks Jimbo165
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Phantom no output
Thanks for the warning wavrider I have been working with high voltages before and suely know the dangers for sure. I do not think problem is related to keying because when I key radio into amp all amp relays working and switching like they should also I have voltage at top of tubes when keying up and when I change switches from low,medium and high voltages change there like it should just no watts going out back end. I cleaned relays and no difference may replace relay at antenna but just dont think this is it for sure . Believe something to do with switching but just donot know what. Amp now belongs to me as I traded my brother another amp and cash for it. It is such beautiful shape looks great. Please give me things to try Thank You Jimbo165
Thanks for the warning wavrider I have been working with high voltages before and suely know the dangers for sure. I do not think problem is related to keying because when I key radio into amp all amp relays working and switching like they should also I have voltage at top of tubes when keying up and when I change switches from low,medium and high voltages change there like it should just no watts going out back end. I cleaned relays and no difference may replace relay at antenna but just dont think this is it for sure . Believe something to do with switching but just donot know what. Amp now belongs to me as I traded my brother another amp and cash for it. It is such beautiful shape looks great. Please give me things to try Thank You Jimbo165
when you key the amp is it drawing any current plate ? If the meter on the front of the amp is in circuit you should see some current reading?
If it keys you may want to see if any RF is getting to the cathode of the tubes.
With relays keying, and if it is drawing plate current, then it is a drive problem ( no rf getting to the tubes) or an output problem, tank circuit.
with the amplifier un plugged and HV bleed off the caps. I would ohm the RF circuit from the input to the cathode through the relays.
I would also ohm the rf output circuit from the blocking cap to the output through the relays.
Interesting statement you made, I think if memory serves me correct that D&A switched from drive stage to final when going from hi power to low power. The voltage remained the same on the tubes no matter what setting the amp was on?
If it keys you may want to see if any RF is getting to the cathode of the tubes.
With relays keying, and if it is drawing plate current, then it is a drive problem ( no rf getting to the tubes) or an output problem, tank circuit.
with the amplifier un plugged and HV bleed off the caps. I would ohm the RF circuit from the input to the cathode through the relays.
I would also ohm the rf output circuit from the blocking cap to the output through the relays.
Interesting statement you made, I think if memory serves me correct that D&A switched from drive stage to final when going from hi power to low power. The voltage remained the same on the tubes no matter what setting the amp was on?
Phantom no output
Thanks wavrider I will do all you have suggested I have put amp on shelf for right now as we are getting ready for this weeks Hamfest and just kinda tired of working on stuff want to enjoy radio for a couple weeks then will jump back in. I want to thank you and others very much for the comments and help for sure.
Jimbo165
Thanks wavrider I will do all you have suggested I have put amp on shelf for right now as we are getting ready for this weeks Hamfest and just kinda tired of working on stuff want to enjoy radio for a couple weeks then will jump back in. I want to thank you and others very much for the comments and help for sure.
Jimbo165
Also, if you haven't checked them already, pull the driver tubes and check the junction between the cathode and the corresponding pin that it ties to. I've seen a lot of Phantoms have no output because the driver section got too much RF input from the radio, and it pops the cathode junction on the driver tubes. If the junction is popped on the tubes, throw them away, they are no good and will need to be replaced.
~Cheers~
~Cheers~
The old fusible link. Those are best placed outside the tube but for TV sweep tubes it was easier to add this safety device inside the tube. The 8950 and M2057 had dual cathode pins that supported twice the current if they were paralleled. Many were not and would burn one junction open. Pin 7 could then be paralleled to the cathode circuit and service restored.
