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NEED Parts for Heathkit HR-1680 Receiver

Discussion in '"Boat Anchor" & Classic Equipment' started by KM4HNF, Dec 1, 2016.

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  1. KM4HNF

    KM4HNF Ham Member QRZ Page

    I picked up another nice Heathkit HR-1680 Receiver, but found out it is missing a fe components on the AUD/REG Circuit Board. Two or three of the parts are resistors, which I can find without difficulty, but the other two are #205-614 Heat Sink, and what looks like item Q201 shown at the top of the circuit board drawing, page 41 of the manual, pictorial 4-9. The parts list appears to show this as part #417-852 with description TIP31 transistor. All of the is a tad confusing to me.

    What would be the best place to locate these parts, original or otherwise.

    Would this part shown on the radio shack site be the same thing??

    As for the heat sink, can I make my own if original not available?

    Any help greatly appreciated. I have another HR-1680 that I got up and running, and it receives really well. Thought I would try to get this one going too, and maybe sell one or the other.

    Thanks in advance,
  2. K7TRF

    K7TRF Premium Subscriber QRZ Page

    Yes, the RadioShack part will work, but the TIP31 is a common transistor. Here's a datasheet on the device:

    You can also find these from vendors like Mouser, Digikey, Newark Electronics or even eBay:

    I haven't pulled up the Heath manual to see what the heatsink looks like, but there are many heatsinks available from those same vendors listed or again eBay such as:

    Be sure to get some heatsink compound as well as it helps with heat transfer between the transistor and the heatsink.

  3. KM4HNF

    KM4HNF Ham Member QRZ Page

    Sorry about the Alzheimers moment.
    By the way though, despite the fact that I found the TIP31 on radio shack site, I still need an answer about the heat sink, and the
    IC201, 78MGT4C IC (Radio Shack also?)

    Thanks one more time
  4. KM4HNF

    KM4HNF Ham Member QRZ Page

    Thanks for the quick reply!! Didn't even see it haha.
    Do you know if that IC201 78MGT4C is a current part still available?
    Thanks much
  5. KM4HNF

    KM4HNF Ham Member QRZ Page

    Also just found this page showing modifications/ updates on a service bulletin for the HR-1680 which might be of interest to others with this radio.

  6. W9GB

    W9GB Ham Member QRZ Page

    STOP !
    It is very likely additional modifications may have been performed by earlier owner/builder.
    Stop shopping at Radio Shack (China direct is cheaper).
    Mouser and Digi-Key have good parts.

    78MGT4C : This is a Positive Voltage Regulator (Adjustable), likely Heath part number: 442-626.
    This was a 4-pin part -- it will require some circuit tracing (and thinkung)
    The 78MGT4C part was used by Heath in other kits (1980s), TO-220 case.
    The part number is Obsolete, BUT a LM-317 could be used -- WITH SOME WORK.

    READ (2001 discussion for another Heath product):
    I then subbed in an LM317 for the UA78MGT4C regulator, since mine was bad. I had to do some pin-swapping of the two regulators, though, which wasn't any great surprise - pin 1 (317) to pin 3 (UA78), pin 2 to pin 2, pin 3 (317) to pin 1.
    (UA78) 4 of the UA78 location was left unconnected.

    In other words, he is reporting that numbering is backwards (flip the LM-317).
    HEAT SINK, should be standard TO-220 style .... junked PC power supplies are filled with them.
    Photo below is Horizontal position. Verticals are popular, with 2 tabs holding heat sink upright, as shown in second photo below.
    IMG_3607.JPG IMG_3609.JPG

    Texas Instruments LM-317 datasheet

    There are YouTube videos (several), regarding usage of an LM-317. Get your popcorn, learn.

    Lessons about LM-317T
    Last edited: Dec 2, 2016
    K7TRF likes this.
  7. K7TRF

    K7TRF Premium Subscriber QRZ Page

    Yes as W9GB posted above that's a voltage regulator (adjustable if I recall correctly) you can find something in the 7800 series that performs the same function. These are also standard items from the major electronics parts vendors like Mouser, Digikey or Newark and you can almost certainly find them in small quantities on eBay or other sites as well.
  8. W9GB

    W9GB Ham Member QRZ Page

    I just downloaded the Heathkit HR-1680 HF Receiver Assembly Manual.
    IC201 is shown as LM-317

    PAGE 41, Pictorial 4-9 (AUD-REG board) shows IC201 using an LM-317 regulator.
    ???? Confused by your question, unless this was a production change.????

    Heath has you fabricate a heat sink -- AND --
    that Heat Sink is Electrically HOT (Not grounded).
    You can see this through usage of nylon shoulder washers.
    Nice "beefy heat sinks, in this size, are found in those dumpster computer power supplies.
    Last edited: Dec 2, 2016

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