Wednesday, January 20, 2021

Guilt Trip: Video on the Heath QF-1 Q Multiplier


Hack-A-Day had a nice post about this piece of gear: 

My radio emotions were swinging wildly as I watched this video. 

Readers may recall that over the years I have brutally cannibalized several QF-1s.   I was enticed into doing this precisely by the tuning cap that the videographer so alluringly describes.  It has a  built in 7:1 reduction drive!  How could I resist?  These wonderful caps live on in several of my homebrew rigs.  

I also put the conveniently sized metal cabinets to good use -- one holds frequency counters for my AM station, the other houses an Si5351 VFO/BFO that can be used with many rigs. 

After extracting the cap and putting the boxes to good use, I was left with the remainder of the circuitry.  I recently put even this stuff to use by using the coils to make a triple LC circuit filter for 455 kHz.  This may someday be used in a receiver.  So you see, I've not been wasteful. 

And the thing only cost 9 bucks back in the day...  So I didn't really do anything bad.  And besides, adding a regen circuit to a superhet is kind of backwards, right? 

But then the video producer started talking about how nice his QF-1 looks, even after more than 60 years.  And about how much it improved the performance of his AR-1.  And then, the kicker:  He said the QF-1s are now "relatively rare." 

I hang my head in shame.  I am a serial QF-1 killer.  And I don't know if I can stop. 


at

2 comments:

  1. TonyJanuary 20, 2021 at 6:25 PM

    I think it is a forgivable sin.
    I've often thought that if I ever found a cheap Heathkit HW7 I would throw the insides out and build something decent in there - perhaps with an arduino and Si5351. Just to torture the Heathkit purists you understand ..... :-)

    ReplyDelete
  2. ka9pJanuary 21, 2021 at 12:49 AM

    Oh Bill, we must stop you before you kill again! I guess you’re just a radio capitalist, putting an asset to its highest value. Bezoar would be so proud:)

    But maybe you undervalue it. After watching WU2D’s HR10 video where he built a 1680 kHz Q multiplier, I put a QF1 on 500 kHz and still use it with a 51J, and have modified another one hoping to use it with the HR10. I bet there’s an S38 there wishing it had a poor man’s 2BQ. That’s an analog joy Pete may never experience 🙈

    ReplyDelete