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  1. DoctorAudio

    Metal oxide resistors for dummy load in oil - do they last?

    Just for reference, the resistor in the Heathkit Cantenna is a 50 watt unit. Submerged in oil it was rated/able to handle 1000 watts intermittently.
  2. DoctorAudio

    Texas Star DX35O Smoked

    Once R8 opened, straight 12 volts went to the bases and would have blown both transistors and 10 ohms. It seems strange that R8 smoked again when you powered it back up after replacing it. Were you using your friends power supply? If so you might want to measure the output voltage and make sure...
  3. DoctorAudio

    DX 1600

    One thing you can do to ensure symmetry between each 2 pill pair is to install one red dot and one non-red dot into each 2 pill pair. That way if there is a small imbalance, it's absorbed by the output transformer core and not the combiner resistors. I've done this successfully a number of times...
  4. DoctorAudio

    How do you regulate a 150 amp power supply.

    20 volts DC, no-load doesn't give enough headroom to regulate to 15 volts. You would need a transformer that floats (rectified and filtered) around at least 25 volts DC with no load. (transformer that delivers 18 volts AC, RMS)
  5. DoctorAudio

    Blue"palomar"skipper 2 transistor amplifier Low output

    Check the value of the silver mica cap across the output transformer. It's probably gotten hot and dropped substantially in value.
  6. DoctorAudio

    OKAY I NEED SERVICE MANUAL FOR COURIER CENTURION PLL 40 CH

    Just to add more info for confusion, the schematic that came in the box with every new Gladiator PLL40 mobile was actually the schematic for the Spartan PLL40 mobile (which is wrong). As far as I've seen their is no "actual" direct schematic for the Gladiator. When aligning/repairing a...
  7. DoctorAudio

    TX Star 250 dx SWR ? (Something lost it's value ?)

    Yes, you could probably lower it to 1000pf and get "some" of your peak power back but I wouldn't go any lower than that. Besides, some of the power you were seeing could have been ghost watts from the SWR anomaly and not real anyway. Cheers though either way, I'm glad it worked!
  8. DoctorAudio

    TX Star 250 dx SWR ? (Something lost it's value ?)

    C14 is usually the culprit, especially if it's a Mica (kidney bean). If C14 tests fine you can always check the value of C16 as well as both of these caps endure a lot of RF current.
  9. DoctorAudio

    TX Star 250 dx SWR ? (Something lost it's value ?)

    If you are getting a high output standing wave on high dead keying, does it drop when you modulate? If so I have a possible solution. Some of the early DX250's and/or Killer Bee 250's ran a lower value mica cap across the output transformer. (430 or 510pf). That in and of itself isn't...
  10. DoctorAudio

    President Andy2

    I'm not sure why but when I first saw the title of this thread, my brain saw "President Handy Andy2" ;)
  11. DoctorAudio

    DROP DOWN and POP-UP ADS ARE A PITA.

    Signing in from a desktop using Firefox with Adblock plus I never see ads or pop-ups. Are you signing in with a phone? Of course I also use NoScript but on this site I'm only blocking anything Google.
  12. DoctorAudio

    Banjos on 28 AM location?

    If they are the Deliverance Banjo's, according to Wikipedia it's the northern Georgia wilderness.. ;)
  13. DoctorAudio

    Cobra 2000GTL 10-Volt blues hit parade.

    C84, the 1000uF 10V next to the PLL as well.
  14. DoctorAudio

    Troubleshooting Muddy buzzing receive D&A Mavrick

    (After you discharge the high voltage) Check the relay that switches on the high voltage that feeds the plate chokes. If one of the contacts is welded closed, you can get "diode noise" from the tubes being energized while you are in receive mode. Diode noise usually sounds like a "bubbly"...
  15. DoctorAudio

    Courier ML100 for SSB

    The combination of C13, R7 and R8 set the oscillation frequency and base bias of the inverter transistors, don't mess with C13.
  16. DoctorAudio

    Realistic TRC-221

    I wonder if the TRC-222 is similar: http://73.235.100.209/radios/realistic/trc_222/index.html
  17. DoctorAudio

    CBtricks web site is up

    Bluehost is/was the host. It's located in Utah.
  18. DoctorAudio

    Teaberry Model T 40 Channel CB Base Station

    Dmans is right, lots of tube radio's do that at first for a short time as the filaments come up to temperature but I was assuming you meant it was a slower process over several minutes.
  19. DoctorAudio

    Teaberry Model T 40 Channel CB Base Station

    Does the signal meter still work on TX and if so does it read the same as the radio warms up? Check the squelch when it's cold (with no signal) and note on the knob rotation where it just squelches the static. Does that squelch point change as the radio warms up? The S-meter and the squelch...
  20. DoctorAudio

    Re capping My Cobra 2000gtl and have a question about cap alignment

    Yes, on that circuit C25 has the + going to ground. It's because there is a negative voltage with respect to ground happening there.