Restoring Heathkit HW-101...

Discussion in '"Boat Anchor" & Classic Equipment' started by KE0EP, Mar 5, 2019.

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  1. W5RKL

    W5RKL Ham Member QRZ Page

    If you believe this problem becomes too much for you, I could be willing to have a look at it.

    I'm good in call sign lookup.

    Mike W5RKL
  2. WA5ZOV

    WA5ZOV Ham Member QRZ Page

    Thanks Mike! Will try crystal calibrator test. I don't have a signal generator-limited to a decent VTVM and that's about it. Will poke around a bit more but may see if you can take a look at it. It would be great to have it operating correctly.


  3. W5RKL

    W5RKL Ham Member QRZ Page


    The 6GW8 has nothing to do with low receiver gain.

    There are only a couple of reasons to replace a tube

    1. Physical damage that caused a loss of vacuum in the tube (Silver Barium Getter coating has turned White)
    2. Troubleshooting results point to a defective/bad tube
    3. Filament doesn't light up due to an open filament
    4. Wrong tube being used as a substitute. 6AU6s can be used to replace the 6SH6 tube for V10 and V11
    on the DRIVE board. Heathkit did that in later HW-101 kits. My 2 HW-101s have 6AU6s for V10 and V11.

    Set the MODE switch to either USB or LSB
    Set Band switch to any band. It doesn't matter which band since no RF is involved
    Set MIC/CW LEVEL control fully CCW
    Set meter switch to PLATE
    Press the microphones PTT. Do you see 50ma indicated on the meter (meter points to the
    triangle above "3" on the meter face)? If so then the final amplifier's idling current is what
    it should be.

    Connect the HW-101 to a 50-ohm load
    Leave meter switch set to PLATE
    Set the FINAL control so it points to the band segment on the front panel

    Set the Load control (tab knob control) fully CCW to its stop

    Set MODE switch to TUNE

    Rotate The MIC/CW LEVEL control until you see a rise in PLATE current indication.

    Adjust the PRESELECTOR for a peak PLATE current indication

    Adjust the FINAL control for a maximum "dip" in plate current

    Set METER switch to REL PWR

    Alternate between FINAL and LOAD controls for a peak in the REL PWR meter indication
    Stop adjusting when there is no increase in REL PWR meter indication.

    Switch meter to PLATE. The meter should display approximate 250ma. If it's higher then
    rotate the MIC/CW LEVEL control to reduce the PLATE meter indication to 250ma.

    250ma is when the PLATE meter points to "40" on the S meter scale. If this is what
    you see then the final amplifier is working as it should. How are you determining the
    HW-101 is only producing 30 watts output? Are you doing this in sideband while
    talking into the microphone? Are you using a wattmeter to display power output?
    Do you have a 50-ohm dummy load?

    If you don't have a dummy load then I recommend you get one. I use an MFJ-260C 50-ohm
    dry dummy load on the bench but a 1KW dry dummy load at the operating position. Every
    ham station should have and use a 50-ohm dummy load to tune the transmitter(s) into.

    Mike W5RKL
    KE4OH and N2EY like this.
  4. WA5ZOV

    WA5ZOV Ham Member QRZ Page

    Hi Mike,
    Did the calibrator test-no signal. I have gone thru the set up and trouble shooting steps in the manual and have found nothing amiss. I don't have a signal generator and probe-test equipment limited to a VTVM. Any other obvious thing to look at? If you were willing and I am stuck I'd love to send it over to you in Oklahoma-I'm in Utah. No rush but if you would look it over and give me idea of cost to get it operating I would be very interested. Thanks for your help!

    john WA5ZOV
  5. W5RKL

    W5RKL Ham Member QRZ Page


    Measure the calibrator V17A plate voltage (pin 1). V17A is the 12AT7 on the Band Pass board,
    Pin 1 is the pin on the "Right" side of the large space on the socket. The pin numbers are oriented
    "counter-clockwise" when viewing from the top of the socket versus "clockwise" when viewing the
    socket bottom.

    With the FUNCTION switch set to any setting other than CAL (turns calibrator OFF), the V17A pin 1
    plate voltage should be close to +300VDC. Set the FUNCTION switch to CAL (turns the calibrator ON),
    V17A plate voltage should drop to approximately +127VDC. If V17A plate voltages remain at +300VDC
    with the FUNCTION switch set to CAL then the calibrator is not turning ON. This could be caused by
    a broken wire on the FUNCTION switch, a very dirty FUNCTION switch, bad/failed 100Khz crystal or
    V17 is bad. The calibrator is turned ON by grounding V17A's cathode through the FUNCTION switch
    in the CAL position.

    Mike W5RKL
  6. W5RKL

    W5RKL Ham Member QRZ Page

    Hi John,

    Write me an email at

    about shipping your HW-101 for me to look over. Use "HW-101 Repair" as the subject line.

    Mike W5RKL
  7. WA5ZOV

    WA5ZOV Ham Member QRZ Page

    Hi Mike,
    HW101 getting great audio reports-quite stable when warmed up. Gets lots of compliments! Working on audio hum. Replaced and regrounded shielded audio cable. Hum almost non existent on speaker but loud on headphones. Two questions:
    1. Manual calls for hi impedance phones. My MFJ phones only 16 ohms. Do I need different phones? What is considered hi impedance?
    2. Could there be issues with headphone circuit that would add to the audio hum? Or is it picking up hum still there? All grounds look good but certainly may be missing something.
    Thanks for all your help. The rig works great-stations break in when they hear it is a “hot water” to complement. Great fun!!

    John WA5ZOV
    KE4OH likes this.
  8. W9GB

    W9GB Ham Member QRZ Page

    John -

    Mark Graalman, WB8JKR (sk, 2005) wrote a 9 page short article, that you should copy and keep on your computer hard drive.
    Optimizing the Heathkit HW-101, SB-100 to SB-102 Transceivers
    You can find that document, here:
    The First Modification (with Pictorial)
    Conversion to Low-Z Headphones:
    The Heathkit HW-101 wee designed to be used with Hi-Z headphones,
    but if low-Z phones are used the outboard speaker will not mute completely with the phones connected.
    To convert to low-Z phones, make the following wiring changes referring to (Figure 1) of this document, and pictorial 8-4 (foldout from page 53), and pictorial 8-5 (foldout from page 67) of the HW-101 manual.
    N5OLA likes this.
  9. WA5ZOV

    WA5ZOV Ham Member QRZ Page

    Thanks! Downloaded and saved.

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