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DX 60 question

Discussion in '"Boat Anchor" & Classic Equipment' started by KB1FGC, Oct 25, 2021.

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  1. KB1FGC

    KB1FGC Ham Member QRZ Page

    Hi,I made a sketch of a tiny portion of the schematic of both the DX-60B and DX60A Heathkits power supply section.I am having an issue with the it.I have it on a dim bulb testor and the light bulb pulses on and off.I checked my wiring and I noticed that I have the bypass caps wired according to the DX60A.I have upgraded to the DX60B power supply.I got the kit from Hayseed Hamfest.Should I wire the bypass caps according to the DX60B schematic?Could that be causing the issue?I don't know for sure but it looks like the DX60A had the primary wired for only 120V,so I don't think that I could of wired it for 220v.Correct me if I'm wrong.

  2. W9GB

    W9GB Ham Member QRZ Page

    I would suggest you wire your Heathkit DX-series transmitter for the … Model You Have.
    DO you have the correct Assembly and Operation Manual??
    Heathkit DX-60 Transmitter Manual

    Heathkit DX-60B Manual

    Mike, W5KRL is a good resource.
    In addition,
    IF are maintaining a two-wire AC power cord —
    THEN wire properly with Safety Capacitors & Polarized Plug — avoid Hot Lead to Chassis !!
    Heathkit of the Month #3
    Heath DX-40 Amateur HF Transmitter
    by Bob Eckweiler, AF6C

    Heathkit DX-60, 60A and 60B Transmitters
    In 1962 the DX-40 was replaced by the restyled DX-60 (1962 - 1964),
    the DX-60A (1965 - 1967) and the DX-60B (1967 - 1976).

    The Heathkit DX-60 was based on the DX-40 except that it now came in a more modern low-style case and featured the new Heathkit green styling.
    Electrically, the power supply was changed from a fullwave tube rectifier with choke input filter to a voltage doubler circuit utilizing silicon diodes with a capacitor input filter.

    In the DX-60B the power transformer had dual primaries so the radio could be wired for 240 volts. The keying was changed from cathode keying to grid-blocked keying. A low-pass filter was built into a shielded box at the back of the rig. A new neon pilot light adorned the front panel.

    The meter was mounted behind a metal bezel on the original DX-60, but was later moved back directly to the front panel. Two new controls adorned the front panel, a drive level for adjusting the grid current, and the crystal VFO switch that was on the back panel on the DX-40.
    The DX-60 series had provisions for four internal crystals instead of three.
    The DX-60 series had an accessory socket, similar to the DX-40 with added connections for keying the VFO and for removing plate voltage when using a crystal.
    N2EY likes this.
  3. KB1FGC

    KB1FGC Ham Member QRZ Page

    Thanks for getting back with me.I wired for a 3 conductor power cord.I recapped and changed out the bypass caps for new ones.Also changed the old style circuit breaker to a fuse on the plus side.The wiring on the primary is set up as per the DX60A manual which I have.From what your saying,It seems the arrangement of the by pass caps wouldn't be effecting how the radio is operating so I suspect it must be something else.
  4. K7TRF

    K7TRF Premium Subscriber QRZ Page

    If your series wired dim bulb tester is pulsing on and off you have a pulsing short circuit somewhere. That could be an electrolytic cap breaking down (even new caps can fail or can be wired backwards) or something else. I'd probably disconnect everything in the rig beyond the power supply and see if the dim bulb continues to blink. IOW, divide and conquer to see if the short is in the power supply itself or somewhere in the transmitter's circuitry. Of course before even applying power again I'd double and triple check that you installed all the replacement parts like capacitors and diodes in the correct orientation and there are no wiring errors.
    N2EY likes this.
  5. KB1FGC

    KB1FGC Ham Member QRZ Page

    Hello,Thanks for the email.I had rechecked all my wiring 2 days ago and it seems right..The caps that I installed were checked before installation.The rig was known to be working prior to my purchase.I opened the case and observed that the relay is making the clicking sound.At first it clicked on and off with the switch and the light was not on on the dim bulb light.After about 4-5 seconds the relay starts to click,fluttering on and off really fast and the light kicks on in the testor.It seems now that the light comes on much fast now and the relay doesn't work as well.So like you said maybe a cap is shorting.I found out this,The larger caps measure correctly, The caps were tested in circuit.I noticed that the 2 smaller caps( C37 and C38 in the DX60A manual) that are 22Uf each are reading very small capacitance and pulsing.I can be sure but I but I seem to remember them at about 44 Uf when I installed them.The 44Uf seems to make sense.if the caps are blown something must be causing it.I do have someone coming over soon I hope as I have other rigs that need the meantime I'll check out what you say
  6. W5RKL

    W5RKL Ham Member QRZ Page

    Replace the 2 pin power cord with a 3 wire grounded cord and throw those by-pass caps in the trash can.
    I do not use those caps with a 3 wire grounded power cord.

    You should also replace that 3 amp circuit breaker with a single fuse holder mounted in the inside rear apron
    area (click the link below to see that area where I mounted the fuse holder).

    If you don't have the DX-60A complete assembly manual then spend the money and purchase it! You should not attempt to
    service the DX-60A without it. You can find it here for $26 plus a few dollars USPS shipping.

    C37 and C38 are the "bias supply" filter capacitors mounted to the left of the 4 HV diodes.
    They are 20ufd at 150VDC NOT 44ufd. Modern 22ufd at 160VDC axial lead capacitors are
    good replacements.

    C39, C40, C41, and C42 are ALL 40ufd 450VDC capacitors. C33 is a larger 20ufd
    350VDC axial lead capacitor next to the Function switch. C40 and C42 are both in the
    metal can capacitor mounted on the top of the chassis. C39 and C41 are the 2 axial lead
    capacitors mounted below the chassis between C40/C42 and terminal strip "G". Modern
    47ufd 450VDC axial lead capacitors are good replacements for C39 and C41. The same
    applies to C33, a modern 22ufd 350VDC axial lead capacitor is a good replacement for
    C33. Make absolutely sure you have the capacitors polarity leads connected CORRECTLY.
    If they are connected BACKWARDS then the capacitor can be damaged and possibly
    the circuit they are connected could be damaged. This is why you need the proper
    assembly manual for the right DX-60.

    Mike W5RKL
    Last edited: Oct 29, 2021
    N2EY likes this.
  7. KB1FGC

    KB1FGC Ham Member QRZ Page

    Mike,THanks for the is what I did.Easier to see in a picture than for me to describe it.I circled where I put the fuse,rectifier, filter and C37 and C38.You can see the relay as well..I was going to go with a fuse like you had but ended finding the style fuse like you see.I thought maybe the fuse was shorting to the bottom of the cover but it isn't.I tried it with the cover off.The old style caps, C37 and C38 looked like one cap that read 20uf X 2. If I remember correctly.That might be where I came up the 44Uf across both of them.I have the correct caps and checked from what you told me and they are good.The only difference is,I have a 450V rating for C33,same capacitance though.I got the components at Hayseed hamfest.
    I'll ditch the bypass caps.I got them because I read online that they help filter RFI so figured I might as well put them in.I do have a 3 prong power cord.Thanks for the link on the manual.I ordered from the Manualman and was very pleased with the manuals.I didn't know of the webpage that you recommended. Nice to have another source.I have the DX60A.I agree with you,The manuals that I saw online were incomplete and I didn't want to take a chance using them even if there small differences between them.As far as I can tell I connected everything correctly.I checked again 2 days ago and went through it all.This rig was a little bit more work upgrading to the DX60B supply becuase at some point a previous owner put a choke in the power supply and had the C38 cap already installed.That had caused a bit of confusion at first.
    Check the picture out and let me know what you think?
    Oh,I did put in an in rush resistor between pin 4 of V4 and the anode of the diode in the recifier for the function switch was suggested so I did it.The Ohms are very low at 4.7ohms.I don't see that being the issue.The relay was working very well at first.
    Thanks again!
    Rich KB1FGC
  8. SM0AOM

    SM0AOM Ham Member QRZ Page

    You should be aware that there is no relay mounted in any DX-60 from the beginning. Any relay is an "after-market" addition, usually put there to avoid wearing out the Function switch.

    It is necessary to trace out the actual wiring to find out what the relay does, and how it is connected to the rest of the circuitry.

    My "hunch" is that the relay coil is operated off a "weak" supply with insufficient current capacity to keep the relay closed when it closes and supplies the rest of the transmitter.

    By tracing out the actual wiring, it becomes possible to find out what part is causing problems.

    I also strongly suggest obtaining qualified local assistance from someone familiar with tube electronics.

    N2EY likes this.
  9. W5RKL

    W5RKL Ham Member QRZ Page

    I replace those #6x32x3/8 machine screws that secure the couplers to the band switch and xtal/VFO switch with #6x32x3/8"
    hex set screws. The fuse holder's tip connection appears to be quite close to those coupler set screws.

    The relay "appears" to be the Function switch 260VAC modification. You didn't say you installed the relay so I'm going to assume
    you didn't. I would not have installed it where it is currently mounted. The wire routing is poor which can possibly create a problem as the
    wiring is routed "over top" of the speech amp and modulator tube circuits. There is much more room between the 2 shafts where the
    relay could have been mounted. Yes, you would have to drill a hole to mount the relay.

    Yes, the original bias supply filter capacitors were single enclosed 20ufd capacitors. Hayseedhamfest DX-60 capacitor kits provide 2
    individual 22ufd 160VDC axial lead capacitors to replace the original dual encased 20ufd 150VDC capacitors. The two 20ufd capacitors
    act separately so when measuring the capacitor values you connect your capacitor checker between one positive terminal to
    the negative terminal of each capacitor NOT across both positive terminals.

    Below is a picture showing the Function switch 260VAC switching relay I used. It's a 6VDC DPDT relay with contacts rated at 250VAC
    at 8 amps. One-half of the relay is used to switch the 260VAC. The other half of the relay which is NOT part of the Function switch
    modification is used to provide a receiver muting socket on the rear of the DX-60. Depending on how the receiver mutes determines
    whether to use an N.O. or N.C. set of relay contacts. Since each half of the relay has a set of SPDT contacts, it's easy to make the muting
    connections based on the receiver's muting requirements. I wire the muting relay using a set of N.C. set of relay contacts. This allows the
    receiver to receive when the relay is not energized. Switch to TUNE, PHONE, or CW, the relay energizes "opening" the relay contacts muting
    the receiver. There are some receivers that require an "Open" mute connection to receive such as the Kenwood R599.

    The DPDT relay I used mounts using a single 6x32x1/2" machine screw. I measured where I wanted the relay to ensure drilling the hole would
    not interfere with the final amplifier tank coil and variable Plate and Load capacitors. I then drilled a small hole to accept a #6 machine screw.
    I fed the machine screw through the hole in the final amplifier to the bottom of the chassis. The screw was fed through a small rubber grommet
    used to help reduce the clicking sound when the relay energizes then into the 6x32 threaded mounting hole on the bottom of the relay. Wiring to
    the relay from the 6VDC supply built on the terminal strip to the right of the relay and to the Function switch used #22awg solid copper wire. No
    wiring was routed over the top of the Speech amplifier and Modulator stages. All the wiring was routed away from any audio or other circuits that
    may cause problems. I did not use a surge resistor, found it not necessary at 6VDC. The diode is a 1N4007 as I have quite a few of these and the
    filter capacitor is 330ufd at 35VDC. If a lower capacitance capacitor is used the relay will "chatter" and NOT fully energize. The 330ufd capacitor
    allows the relay to fully energize without any chatter or hum.

    I no longer have that DX60 but I have since picked up a DX-60, DX-60A, and DX-60B (click the links below). I have not performed the Function
    switch modification to any of these DX60s. Although the DX-60 and DX-60A pictures don't show it, I replaced all of the filter capacitors using
    the Hayseedhamfest DX-60 capacitor kits.

    One more comment. I replaced those ugly #6x32 pan head coupler set screws with #6x32x3/8"
    hex set screws. Some pictures don't show the hex set screws as the hex set screws replaced the
    pan head screws after the pictures were taken.

    DX-60 (Filter capacitors changed)

    DX-60A (Filter capacitors changed)

    DX-60B (Fully rebuilt with new filter capacitors)

    Mike W5RKL

    Last edited: Oct 29, 2021
  10. KB1FGC

    KB1FGC Ham Member QRZ Page

    Nice restorations Mike.I installed the relay.I thought at the time that it may have been a tight fit between the shaft but your fits very nicely.I will put longer wires and wire them so that they are away from the speech amp and modulator tube sockets.

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