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Heathkit HW-104 Thread

Discussion in '"Boat Anchor" & Classic Equipment' started by WA6MHZ, Jun 9, 2011.

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  1. W9GB

    W9GB Ham Member QRZ Page

  2. WA6MHZ

    WA6MHZ Premium Subscriber QRZ Page

    Thanks for the point to that article, I printed it out and it is now on the QUEQUE of just yet another thing to build. It is much better than the other OVP circuits I have. They rely on a SCR to trigger, which more often than not gets triggered by RF (that is happening in my lab PS).
    Not sure I have the room to build it into the HP1144A but I can try. The 40A relay might be a little tough to come across. Maybe an Auto HORN relay will do it. Need to find the IRF510 and the 1N5244B too. Maybe there is a NTE sub for those. Radio shack doesn't carry SQUAT anymore! I found an IRF511 I am going to use in my CW QRP transciever as a final stage. It was made for Radio Shack back in the early 80s. OH, those were the days.

    The good news, (and very good news it is) is that the HW-104 now puts out good power on all bands but 10, and that can be expected 10 will be lame.

    I had won some SB-104 boards on Ebay, and also the very expensive and hard to find Extender board. I almost paid more for the Extender board than I did the whole radio!!!! but I would NOT be outbid and I wasn't. Today, at work, I hooked up the REPAIRED HP-1144 inside the SB-604 speaker (extensive thread on what I went through on that here). I didn't have the OVP circuit in it, but I took a chance, as this would be just for test.

    The new circuit boards were tried and they didn't work much better than the old ones. Good news is that the old ones weren't blown. Bad news is that I squandered around $80 to get these other boards. Well, atleast I have SPARES for my SB-104 and HW-104 now.

    It was time to try the EXTENDER and that allowed me access to the board like never before. Sure enough, there were some trimmer caps on the PREMIX board that had grown out of adjustment. Mousing with those brought the power up to an acceptable level.

    The scope showed that some bands were still lame, but that has to do with those torroids that are pre-wound and encapsulated with wax in coil forms. Not much I can do about those now.

    But I tweaked enough to get the Power Output up to a nice level, and it was time to closer the toy up.

    The HW-104 was then tested for Receiver sensitivity and alignment, and found to be OK. The VFO was calibrated and the rig was ready to put back in the Museum for Museum service.

    This rig will be ready to go for a nice little HF station should it be needed. But now I am SNAKEBIT about the lack of an OVP circuit. I actually need 2 of them, one for each HP-1144 I have (I have one for the SB-104 too.) I am lucky they haven't blown up.

    The FIXED Heathkit HW-104 can be seen in the West Wing of the Crest Radio Museum!
  3. W9GB

    W9GB Ham Member QRZ Page

    Pat -

    That is EXACTLY what Mike Bryce used in his The Protector circuit design - standard ISO relay (off shelf).
    You can wire the socket and use the plug-in version or the solder tab version.
    I supplied Mike with an updated part number for the relay in his QST article
    (the original Tyco relay was discontinued for an RoHS compliant model).

    I have a couple of spare boards and the relays.
    Mike actually designed this board for that Heath SB/HW-104 power supply , so it will fit.

  4. W5WPL

    W5WPL Ham Member QRZ Page

    Interesting thread
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