HR-10b Project

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

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  1. WA2LXB

    WA2LXB XML Subscriber QRZ Page

    Here's some light reading RE higher freq IFs and QMs: http://www.antiqueradios.com/forums/viewtopic.php?t=96230

    What the layman thinks he got out of it: Much less selectivity benefit with a QM at 1600 than 500...and very touchy, but if you want to do it go for it and put a 6:1 vernier on the QM tuner.
     
    N2EY likes this.
  2. N2EY

    N2EY Premium Subscriber QRZ Page

    Interesting discussion.

    It seems to me the Q multiplier solution isn't the best for such a high IF.

    Here are some other ideas:

    1) Get a collection of crystals at 1681 or so kHz and make real IF filters with more poles. That's a bit of a project, and I don't know where you'd get a bunch of crystals at that frequency, but the results could be excellent. (A junker HR-10 is one possible source - maybe turn the 2 pole filter into a 4 pole?)

    2) Replace the first IF stage with a converter that converts the 1681 IF down to 50 kHz or so, as was done in 1950s receivers. Then have selective IF transformers at 50 kHz. Probably need two IF stages at 50 kHz, so the 6BJ7 could be replaced by SS to free up a socket.

    None are simple - and after a while it becomes less work to just build a receiver from scratch. Or, go the BC-453/converter route.

    73 de Jim, N2EY
     
  3. VE3LYX

    VE3LYX Ham Member QRZ Page

    I have one , I use it but not in love with it. (it is my Listerene receiver. I hate it but I use it twice a day.) Of course I feel the same about the DX60B. Anyone who would plug crystal in the BACK of a radio must have been dropped on their head when a baby. Same goes for using fishing line to turn a capacitor. However they do make a practical station for reasonable dollars and that is a good thing.
    donVE3LYX
     
  4. KE4OH

    KE4OH Ham Member QRZ Page

    Since I work CW almost 100%, using the HR-10B for CW is something I have some considerable experience with. I love Q-multipliers, but it's not a real practical solution for this rig as N2EY points out.

    My solution was to add an outboard passive audio filter. I specifically used the one from the Xtal Set Society ( https://www.midnightscience.net/ ). I like theirs because it is designed for 8 ohm in/out. I never use headphones, so this unit does just what I want. Also, I have an an irrational aversion to solid state, so that's another plus for this passive unit. It does diminish the volume quite a bit, but the HR-10 has enough audio gain to overcome it most of the time.

    If you don't have similar quirks in your personality, you might also look into getting one of the fairly common Autek audio filters or building/buying one of the many available active audio filters.
     
  5. WA2LXB

    WA2LXB XML Subscriber QRZ Page

    Thanks Steve...I've got boo coo outboard audio filters...including the MFJ CWF-2 http://www.radiomuseum.org/r/mfj_cw_audio_filter_cwf_2.html

    I could disassemble the MFJ and install it before the final AF amplifier stage, then outboard a 4 position filter selector. Something like this: http://atlas.wireless.org.uk/MFJ CW.pdf

    I'd need a 9VDC source from inside the HR-10B...not sure where to source that. Maybe a step up transformer and rectifier from the ~6VAC filament supply.

    And thanks for the midnightscience link...very cool stuff.

    I agree with the consensus...re-crystalling the radio or adding additional IF transformers is probably time poorly spent.

    BTW...what happened to Dave...W7UUU? I seem to have hijacked his thread:eek:
     
    Last edited: Apr 4, 2017
  6. N2EY

    N2EY Premium Subscriber QRZ Page

    That's easy!

    One side of the 6.3 volt heater string is grounded. Take the other side, run it through a silicon diode from a burned out CFL, into a big filter cap from the same CFL (lots of uF, not many volts) and....voila! 1.414 times 6.3 is .....8.9 volts! (A capacitor-input filter charges to the peak voltage).

    Dave is/was on a trip. See his awesome thread about it here:

    http://forums.qrz.com/index.php?thr...tion-and-r-l-drake-grave-visit-thread.561050/

    73 de Jim, N2EY
     
  7. WA2LXB

    WA2LXB XML Subscriber QRZ Page

    Perfect...I'll hit you up for that schematic once the HR10B is up and I've tried the CWF-2 outboard with phones to test its effectiveness. Thanks for the link to Dave's trip...very meaningful thing he did for himself and as an ambassador for all of us who just can't seem to get Heathkit out of the bloodstream.
     
    N2EY likes this.
  8. VE3LYX

    VE3LYX Ham Member QRZ Page

    I find in HF operating that initially it is very handy to have a wide front end. Once you find UR victim then it is nice to be able to narrow it down some . Call me crazy but prefer a AF filter. It is for me more practical.
    Don Ve3LYX
     
  9. N2EY

    N2EY Premium Subscriber QRZ Page

    Funny - I'm the opposite - I prefer a narrow IF filter, backed up by audio. With a good slow tuning rate, no problem finding stations.

    To each his own!
     
  10. VE3LYX

    VE3LYX Ham Member QRZ Page

    Absolutely.
     

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