HR-10b Project

Discussion in '"Boat Anchor" & Classic Equipment' started by W7UUU, Feb 13, 2016.

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  1. W9GB

    W9GB Ham Member QRZ Page

    Jim -

    Sounds like a great approach, to minimize modifications (especially to that drop in pre-assembled module, more like TVs of that era). The Drake 2-series took a similar approach, in using 80-meters (3.5-4.0) for the higher bands.
  2. N2EY

    N2EY Premium Subscriber QRZ Page

    Yes, the Drakes did that, as did the Mosley CM-1. It was also a common practice in Handbook receivers, and a way to improve the performance and/or extend the range of older and surplus receivers. Several Southgate Radio receivers used the method as well.

    If it were me, the converter and a crystal calibrator would be built in a separate cabinet similar to the HC-10 accessory @W7UUU described.

    The performance of the HR-10 on 80 and 40 is probably good enough that only 20, 15 and 10 really need the converter.

    As mentioned before, one of the main reasons the HR-10 is so "deaf" in the higher bands is that the design of the front end results in very high C and very low L on those bands. Fixing this would require a complete redesign of the front end, using additional bandswitch sections and replacing most of the Ls and Cs there. Not a simple or easy job, and the dial calibration almost certainly won't match the stock one. Plus, when all the work is done, the stability on the higher bands will probably not be any better.

    Using hotter tubes and changing the mixer might improve things somewhat, but might bring RF amplifier stability and other problems with it.

    Note that the HR-10 front end was supplied as a prewired assembly.

    73 de Jim, N2EY
    Last edited: Aug 10, 2018

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