ad: elecraft

Hammarlund HQ-200

Discussion in '"Boat Anchor" & Classic Equipment' started by WB3JIH, Aug 10, 2017.

ad: L-HROutlet
ad: l-rl
ad: l-assoc
ad: Subscribe
ad: MessiPaoloni-1
ad: L-MFJ
ad: l-BCInc
  1. WB3JIH

    WB3JIH Ham Member QRZ Page

    Hi all -

    Starting a rebuild of the above. Cosmetics were reasonable, but has definitely experienced some less than tender mercies in its past at the hands of a "refurbisher."

    So far, visible problems include a bad audio transformer, and the BFO variable cap has been cracked in half, with an attempt at epoxy repair (which did not hold.) The rest of the iron seems OK.

    Advice or knowledge requested: Specs for an audio transformer from a 6AQ5 output to 4.2 ohms, and recommendations for finding a MAPC50B equivalent Hammarlund air variable. RF parts sells a MAPC50C, but I need the one with the shaft on it as this is the BFO adjustment on the front panel. I've searched most of the usual sources, but can't seem to find the shaft version of the cap - they all are slotted with the nut ferule.

    I'm also thinking that the audio output transformer should be reasonably common, but neither the manual nor schematic speak to its specifications.

    Not to make this into a WTB post, but if anyone has a parts donor, especially for the 3.2-50 pF variable, it would be most appreciated. Please reserve flames as there's no ill intent: just frustration.

  2. KE4OH

    KE4OH Ham Member QRZ Page

    The audio transformer for a 6AQ5 is *not* critical. Any chance you have the remains of an old tube AM radio in your junk box? That transformer will work just fine. Basically, any "single-ended" (as opposed to a push-pull) audio transformer of 5k - 10k ohm primary to 4 - 16 ohm secondary will be fine. Don't need to spend a lot on this. Again, a junkbox piece is a great replacement.

    Try Dan's Small Parts for the variable cap. Google the web address.

    You willing to try another epoxy fix on the cap? Try this: Go to the hardware store and buy 2 items. 1) Can of spray "electrical connector" cleaner. This is a solvent contact cleaner without any oil. (In other words, don't use DeOxit, WD-40, or similar lubricating cleaners.) You can also use brake cleaner spray from the auto store. 2) JB Weld 5 minute epoxy. Other brands may work, but I won't vouch for them.

    Now, spray the daylights out of the surfaces you need to join together. You are degreasing. Now, go away for at least an hour to let it dry. Mix up some JB Weld. With a matchstick or similar small item, apply the epoxy to the surfaces to be joined. Join the pieces. Now ALSO spread some on either side of the crack. Now go away for an hour and let it set. I know it is 5-minute epoxy, but it takes longer to get really hard. I've successfully done this to ceramic cap pieces as well as ceramic and phenolic rotary switches. No failures.
  3. W9GB

    W9GB Ham Member QRZ Page

    Hammerlund HQ-200 Receiver : December 1968 to January 1970 (Manual). manuals/Hammarlund/Hammarlund_HQ200 HF Reciever_Service Manual.pdf

    The BFO Control, in the upper right of front panel, is a common variable capacitor.
    Part #: 9434-45-40060 : C59 : Air Variable Capacitor : 3.2 - 50 pFd
    You should be able to find a suitable replacement (antique radio restorers, etc.)

    Surplus Sales of Nebraska (has a few candidates).

    RF Parts has a selection of air variables.
    Hammerlund HF 50 (Looks close to your unit)
    EF Johnson
    Hammerlund, others
    K7PP has a "series of videos" (YouTube) about the 2014 repair/restiration
    of a Hammerlund HQ-200 receiver

    Last edited: Aug 10, 2017
  4. WB3JIH

    WB3JIH Ham Member QRZ Page

    Thanks for the links and info.

    I have the original manual, and had already called RF parts. Surplus sales is specifically "sold out" on the exact part. Unfortunately, nobody seems to have the "shaft" version of the MAC50 -- I don't have a real capability for fabrication, so I was just looking for a direct replacement.

    I'll look in the junk box -- problem is that I don't usually let stuff coming in to the shack become parts -- too motivated to try to make everything work!

    KE4OH: thanks for the advice on repairing the old cap with JB weld -- I may give that a try this weekend if I can get over to the building supply store to get supplies.
  5. W9GB

    W9GB Ham Member QRZ Page

    Viking Technologies in New York purchased the Hammerlund Air-Variable Capacitor Designs/Tooling (Their other business, Viking Solutions, does silk-screen printing).
    They also have the EF Johnson and Cardwell designs.

    Viking Technologies
    80 East Montauk Highway
    Lindenhurst , NY 11757
    Tel +1 (631) 957-8000
    Fax +1 (631) 957-7203

    They will build that specific air-variable capacitor, BUT you need to contact them for price $$.
    **Could they repair your damaged capacitor?**
    Hammerlund MAPC type air-variable capacitors
    Hammerlund Type MAPC air-variable capacitors

    The “MACP” capacitor is representative of Hammarlund’s efforts to meet the demand for smaller dependable components. It is a scaled-down version of the popular “APC” with everything reduced except the quality and performance characteristics. For example, an “MAPC” is about half the size and weight of an “APC.” Lower minimum capacities and low inductance make the “MAPC” suitable for VHF use.

    The standard “APC” construction is used in this capacitor. Rotors and stators are fabricated by soldering brass plates to supporting members and nickel-plating the assemblies. Nickel-plated phosphor bronze wiper assures positive rotor contact. Tapped brass mounting studs fastened to silicone treated steatite base permit mounting capacitor without grounding rotor.

    Straight line capacity. Available either with screwdriver or socket wrench adjustment or with 7/16″ extended shaft for knob control or shaft coupling. “MAPC-C” Lock Type now also available through distributors. Air Gap is 0.0135″ nominal. Tested at 600 V. R.M.S., 60 hertz.

    Optional Base type depicted is not available through distributors. Inquires from manufacturers for this and other modifications should be directed to our sales and engineering headquarters.
    Last edited: Aug 12, 2017

Share This Page

ad: KC0Wad-1