Looking for APX-6 parts

Discussion in 'VHF/UHF - 50Mhz and Beyond' started by N5ZMR, May 22, 2018.

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  1. N5ZMR

    N5ZMR Ham Member QRZ Page

    Hello all. I read a QST article about putting the Air Force surplus AN/APX-6 transpondor on the air on 1296 as a transceiver in QST, September 1960. Last month I decided, it's time to look into that project, and found one on Ebay. It's an already converted unit, by K3NUZ (unfortunately, an SK). I'm not sure if it will be more work figuring out how his conversion works than converting one myself would be, but I'm sure it will be a fun project.

    It's missing one of the knobs on the front, the one that turns the Veeder-Root counter for the Receive frequency. I'm wondering if anyone has an old one kicking around the shack - it would really help me working on this old rig. Also if anyone has any info or advice about how these conversions usually went, I'd like to hear about it.

  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I sure don't have any knobs like that, but you can buy a whole AN/APX-6 that appears complete with everything and looks to be in really nice condx for something nearly 70 years old, for $199 "Buy It Now" price (maybe nobody will offer that and you can get it cheaper):


    I see Fair Radio normally sells these for $95 but currently says "out of stock." You might contact them about parts...

  3. W9GB

    W9GB Ham Member QRZ Page

    Close-up Photo of AN/APX-6 Transpondor
    Unique crank knob with collapsable crank.
    BEST Source are military surplus outlets, BUT this radio has been a surplus item for 60+ years.
  4. WA9SVD

    WA9SVD Ham Member QRZ Page

    One other comment: USE an isolation transformer! If I remember correctly, one side of the IF board (maybe the whole radio) is connected to the AC line. A wrong connection can blow fuses and/or be deadly, whichever comes first! YMMV, but it's better to be cautious than dead.
  5. W1BR

    W1BR Premium Subscriber QRZ Page

    You'd better find two to convert, or you will find there probably are very few compatible radios that you can work... those were wide band and not very stable. I modified one back in the 60s along with a friend.

    There are far cheaper ones on eBay.

    They will require an external AC supply since they were originally used in aircraft.
  6. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    It was common and popular even 50 years ago to use just the output cavity from an APX-6 and use a low power transverter to drive it, making it useful for CW and SSB work. I don't recall anyone actually using the APX-6 "as it was," maybe somebody did.
  7. W1BR

    W1BR Premium Subscriber QRZ Page

    It certainly was used "As is." A few of us locals used them, and I even worked a contest station running one! Real DX, like 20 miles! The referred 1960 QST article was written by Ed Tilton, and modified the APX-6 for use as a crude transceiver on 1215 MHz. Wideband FM, and it used the APX=6 IF strip as well. We made up some neat UHF colinear arrays using wood frames and copper wire... darn things worked quite well.

    Even the old FM Gunplexer duplex 10 GHz systems used wideband FM and were popular at least through the 1980s. In 1960 I doubt that many hams were using transverters and running SSB on 1296 MHz. Heck, the ARRL Handbook was promoting a 6CW4 that did double duty as a modulated oscillator/regen dectector portable for 432 MHz in that era.
  8. K9STH

    K9STH Ham Member QRZ Page


    Like the Vocaline AT-30 amateur radio 420 MHz to 450 MHz transceiver.


    Transmitter, and receiver, tunable across the entire 70 cm band!

    Does the unit run AM or FM? Yes! Supposed to be AM but the FM component is there as well.

    Glen, K9STH
    W1BR likes this.
  9. W1BR

    W1BR Premium Subscriber QRZ Page

    And those ran a hot chassis on AC power! Looks like a clone of their Class B 465 mc. rig.
  10. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I've been on 1296 MHz CW (not FM) since 1968, but using separate TX/RX systems. Started 1296 MHz SSB work in 1972 with a real transverter (about 2W) driving a 2C39A to about 50W. By 1984 had four stacked 55L loop yagis.

    Working the same stations, with about the same signal strengths, over 300-mile paths as worked on 2m was very common: If there was a duct, signals on 23cm were much stronger than on 2m, almost always.:)

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