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Thursday, January 21, 2021

Another Poem about Radio: Radar Man



Thanks to Allan WA9IRS for sharing this with us. 

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. 

Tuesday, January 19, 2021

"The Transistor" 1953 Video from The Bell System

Interesting video. 

-- Good discussion of the transition from tubes.  

-- Go Arlington, Virginia! 

-- Nice video of Bardeen, Brattain and Shockley at work (Shockley does seem a bit off to the side). 

Monday, January 18, 2021

Kevin AA7YQ (Montana Smoke Jumper) Launches his SDR/HDR Build Blog

Earlier this month I posted a note from Kevin AA7YQ describing his effort to design and build a nice transceiver that mixes the best of SDR and HDR.   Kevin has launched a blog in which he will describe the project in more detail.  He is looking for constructive feedback and suggestions.  Check it out: 


Thanks Kevin. 

Sunday, January 17, 2021

STOP. LISTEN. Shep on Building a Shortwave Receiver

Oh man, how could I have possibly missed this one?  Perhaps I didn't, but even if this one has been on the blog before, it is so good that it is worth repeating.  

Shep really captures the frustrations and joys of a teenage radio builder.  I could really identify with this.  It all reminded me of my heartbreaking effort to build the Herring Aid 5 receiver. 

So much cool stuff in this 1963 recording: 

-- The wonderful smell of radio service shops. 
-- The terrible shirt and tie choices of radio service guys. 
-- The truly dire consequences of mistakes in published schematic diagrams. 
-- The AGONY of not being able to get a homebrew radio to work. 
-- The JOY when you finally do get it to work. Shep's "whole life changed" when that happened. 
-- Hugo Gernsback, Lee DeForest and "unscientific scientists."

As the YouTube video plays, they show several covers of old Short Wave Craft magazines. At one point they show some homebrew phone rigs.  I think they look like my wooden box BITX rigs.  And the front panels are clearly Juliano Blue.  TRGHS. 

Here is the 1933 Oscillodyne article that launched Shep's effort: 


Saturday, January 16, 2021

Nick M0NTV's Really Useful SDR Transceiver (video)

Even though I am more of an HDR guy, I really liked Nick's SDR rig.  I like the modular approach, with all the modules inside a transparent plastic box (see below).  Don't worry about the shielding Nick -- I had the same concern about my BITXs in wooden boxes, but they worked fine. 

Nick really did a great job on the video.  The bloc diagram was especially useful, both on the hardware and on the software.  Very cool.   It is nice to use this phasing approach,  with the digital magic happening at audio frequencies.   I fear that soon FPGAs and direct digital sampling will take the hardware fun out of these rigs.  We already have a bit of that with the RTL-SDR dongles. 

Very cool how the Teensy takes care of the 90 degree audio shift.   I had to do that with chips in my phasing receiver. When I first saw Nick's bloc diagram, I was looking for the audio phase shift network -- then he explained that that was in software, in the Teensy. 

Nicks arrangement for switching the filters is very nice.  

Thanks Nick!  


Thursday, January 14, 2021

A Poem about Shacks and Rigs and Ham Radio

The Little Black Box of jewels and rocks
with lanterns that flicker and glow,
make lighter the gloom in my little back-room
where often I hasten to go.
An anthem it peals of whistles and squeals
and voices so ghostly and dear
that you'd never decry, should you chance to pass by-
what a brotherhood foregathers here!

Each separate tone has a soul of its own;
each voice is the voice of a friend.
United through space in this gathering-place
at the radiant signal's end.
Reverberant sounds ride the wave that rebounds,
like the waves of the sea from afar,
reporting the doings, the comings and goings
of brothers... wherever they are.

A curious band, spread over the land,
yet joined from equator to poles
disperses the gloom in the little back-rooms
by this magic communion of souls.
I could part with a lot of the things that I've got,
but I'll carry my love to the tomb,
of that little black box and the joys it unlocks
... when I enter that little back room.

(published in QST magazine sometime 1965.)

Thanks to Jeff Murray for alerting us to this. I had not seen it before. It really got me -- I am working in my little back room on a box with jewels (jeweled movements!) and rocks.

Wednesday, January 13, 2021

Tuesday, January 12, 2021

Pete N6QW and Steve G0FUW Talk to RSGB About Homebrew (Video)

Wow, what an unexpected treat!  Here we can watch Pete N6QW and Steve G0FUW talk to the Radio Society of Great Britain about homebrew radio.  Steve talks about kits and scratch-built rigs.  I really liked seeing his early rigs and his description of how building these rigs helped him become a more advanced homebrewer.  I also liked his mention of George Dobbs as a guiding light in the QRP and homebrew world. 

Pete focuses on SDR and provides a really great description of this approach to homebrew.  I was struck with how great it is that, after a lifetime of HDR building, Pete is willing to embrace this new technology. He talks about it as part of "a learning journey."  As always, he sets the example for us all.   

Thanks to Pete, Steve, and RSGB. 

Monday, January 11, 2021

KLH Model Twenty-One II -- Is My Speaker Dried Out?

A few years back Rogier PA1ZZ very kindly sent me a box of electronics parts.  Included was an FM table-top radio with a nice walnut case.  Thanks Rogier! 

I hadn't looked at the receiver in years, but this week I dusted it off and looked it up on the internet.  Turns out that it is kind of famous.  It was produced by the KLH company.  The K stood for Henry Kloss, one of the giants of Hi-Fi audio gear.  Henry appears in the picture below. 

I got the receiver working, but it sounds awful.  It sounds much better with an external speaker, which is disappointing because the internal speaker was the main attraction of this receiver. It even has a little badge on the front panel trumpeting(!) its "Acoustic Suspension Loudspeaker."

I'm wondering if the problem is in fact the speaker.  The cone looks intact, but it seems very dried out.  It has been more than 50 years...  What do you guys think?  Picture above.  Any other suggestions on what to do with this thing, or how to make it sound better? 

Some KLH history:  



KLH receiver with pillow

Designer: Douglas Bowman | Dimodifikasi oleh Abdul Munir Original Posting Rounders 3 Column