HR-10b Project

Discussion in '"Boat Anchor" & Classic Equipment' started by W7UUU, Feb 13, 2016.

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  1. W9GB

    W9GB Ham Member QRZ Page

    Jim -

    Sounds like a great approach, to minimize modifications (especially to that drop in pre-assembled module, more like TVs of that era). The Drake 2-series took a similar approach, in using 80-meters (3.5-4.0) for the higher bands.
  2. N2EY

    N2EY XML Subscriber QRZ Page

    Yes, the Drakes did that, as did the Mosley CM-1. It was also a common practice in Handbook receivers, and a way to improve the performance and/or extend the range of older and surplus receivers. Several Southgate Radio receivers used the method as well.

    If it were me, the converter and a crystal calibrator would be built in a separate cabinet similar to the HC-10 accessory @W7UUU described.

    The performance of the HR-10 on 80 and 40 is probably good enough that only 20, 15 and 10 really need the converter.

    As mentioned before, one of the main reasons the HR-10 is so "deaf" in the higher bands is that the design of the front end results in very high C and very low L on those bands. Fixing this would require a complete redesign of the front end, using additional bandswitch sections and replacing most of the Ls and Cs there. Not a simple or easy job, and the dial calibration almost certainly won't match the stock one. Plus, when all the work is done, the stability on the higher bands will probably not be any better.

    Using hotter tubes and changing the mixer might improve things somewhat, but might bring RF amplifier stability and other problems with it.

    Note that the HR-10 front end was supplied as a prewired assembly.

    73 de Jim, N2EY
    Last edited: Aug 10, 2018
  3. W7UUU

    W7UUU Principal Moderator Lifetime Member 133 Administrator Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    Blast from the past Zombie Thread Resurrection!

    I finally located a front end assembly to fix the 80m antenna coil... $20 for the whole assembly, in very good shape.

    So hopefully soon this Ol' HR-10b will be back on the air.

    It's now in the shack and actually receives GREAT on 20 and 40!! I added an Autek QF-1A for some audio selectivity and I gotta say it performs better than I ever expected. I can EASILY make a zillion contacts with this setup.

    As soon as the new front end assembly is here, I can replace the broken 80m coil and finish off with an alignment and should be back in business on all three primary bands (don't care at all about 15 and 10)

    Receiver is all wired in with T/R switch - ready to go. Very happy to have found a coil set for cheap :)



    Last edited: Dec 9, 2019
    N7ANN, WD4IGX, W4NNF and 4 others like this.
  4. K9STH

    K9STH Ham Member QRZ Page

    It is not the front end design that is the primary problem with the sensitivity on the higher bands with the HR-10 / HR-10B. The main problem is that the 2nd harmonic of the tunable oscillator is used and not the fundamental. If one can add an amplifier stage to the injection frequency on the higher frequency bands, the sensitivity will improve considerably.

    Glen, K9STH
  5. W7UUU

    W7UUU Principal Moderator Lifetime Member 133 Administrator Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    I didn’t say it was. I have no intention of using this receiver beyond 80/40/20

    the front end chassis I bought to get the 80 meter antenna coil. Just needed the one part

    N7ANN and N2EY like this.
  6. W7UUU

    W7UUU Principal Moderator Lifetime Member 133 Administrator Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    Off to Salt Lake City at the crack of dawn - but chomping at the bit to dig into the 80m coil issue as soon as I'm home.

    My plan is to run the HR-10b/DX-60b rig just as a new user would have experienced "back in the day" but with the single addition of the Autek QF-1A audio filter and see how far I can make it, with everything being stock.

    After I've had a good long shot at that, my plan is to continue the project with OA2 regulation & solid state rectifier. I do notice the RF gain most certainly pulls the frequency down dramatically when reduced. But I have no interest in any mods / upgrades that don't improve CW. What little AM I may try with this rig will be very limited. (Some may recall the DX-60b arrived with the 12AX7 having no grid connection to the microphone jack since day-one. I had my very first every HF AM QSO a couple years ago with my good friend Bryan, @WA7PRC the evening I sorted that out!). And of course, other than a casual listen I have no interest in SSB on the HR-10b. That's just silly, IMVHO.

    N7ANN, KE4OH and WA7PRC like this.
  7. K9STH

    K9STH Ham Member QRZ Page


    You didn't say the problem with sensitivity was the front end, EY said it was.

    A while back, as part of a trade deal, I got an HR-10. The cabinet surface was in bad shape so I repainted it with a crackle finish thus turning it into an HR-10B. Also, aligned, etc., the receiver and added a 3-wire power cord.

    I never even tried to use it on the air because, a couple of days later, another amateur radio operator stopped by, saw the receiver, pulled out his wallet, and started laying $20.00 bills on the table. His first receiver was an HR-10B and he was not going to go home without the receiver!


    For the price of a 3-wire cord, and a few minutes work, I definitely turned a nice profit!

    Glen, K9STH
    KA2CZU and W4NNF like this.
  8. W5RKL

    W5RKL Ham Member QRZ Page

    I picked up an HR-10B without the HRA-10-1 plugin 100Khz calibrator. It was in fair to poor shape, rust on the front panel,
    rust on support brackets, and discolored chassis. I picked up a good shape HRA-10-1.

    I fully restored the HR-10B, cleaned the HRA-10-1 calibrator, then reassembled the HR-10B with all new resistors, capacitors,
    cleaned up the wiring harness, replaced all point to point wiring, new tube shields and tube sockets, and used all new mounting hardware.
    The front panel had bubble corrosion to the point I replaced it with the one I picked up from Tom at The cabinet cover paint
    is not a match to the original. I didn't make any modifications except to replace the RG-8 coax in the front end with a length of
    RG-174 coax. The chassis was sanded and new decals were made using MS Word and clear inkjet decal paper. This restoration was
    a lot of fun and the receiver works as designed.

    For the fun of it, I tapped off the HR-10B's IF and fed it to a RANVerter PI SDR tuned to the HR-10B's IF. All band tuning eas
    performed by the HR-10B but MODE (BFO etc) and audio output was performed by the SDR and the computer speakers. SSB
    AM and CW sounded great.

    I built a homemade PC board 100Khz Calibrator that I installed on a second HR-10B. It worked great. It's mounted on four 6x32x3/8"
    metal standoffs and all wiring, 3 wires, is routed down through the octal socket guide post hole and connected to the octal socket
    pins so the calibrator is controlled by the original wiring to the front panel. The PC board design was made using ExpressPCB CAD
    software and emulated the original HRA-10-1 100Khz plugin calibrator. The calibrator can be easily removed and an original
    HRA-10-1 plugin calibrator can be used.

    Calibrator under test powered by IP-17

    Calibrator installed in the second HR-10B receiver

    Mike W5RKL Moderator
    WA2LXB, N2EY, W1BR and 1 other person like this.
  9. W1BR

    W1BR Premium Subscriber QRZ Page

    All this talk of HR-10 receivers and Dx-60 transmitters brings back painful Novice days... good thing
    no one is restoring a KT-200 or deep depression would be setting in. Back on subject:
    One thing I would try, if I still owned a HR-10, would be modifying a
    Q5'er to work at that IF. Some from coil set parts from donor ARC-5's could be used to convert the
    HR-10 IF down to 85Kc with a few day's effort on the bench. Replace the LO coil and RF
    coil deck, and do some trimming as needed.
  10. N2EY

    N2EY XML Subscriber QRZ Page


    If someone has a working Q5er, it could be used as a tunable IF with a crystal-controlled converter in front of it. Less work and a better receiver.

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