Saturday, July 1, 2017

I've been slackin'

Thanks to Bill, N2CQR for adding a link to my blog on his SolderSmoke page, I've seen a notable increase in the number of visitors, so I feel somewhat shamed into adding something new. Hey, I don't like rushing into things, and it's only been six months, hi.

Truth is, I've been incredibly busy with my current project, and I have to admit that I enjoy working at the bench much more than I do blogging about it.  Not that I don't enjoy that too, but there's only so many hours in the day!

So, what it is, this current project? I call it the "SR-16" and here's a peek:

Those acquainted with early 60's rigs will likely notice a resemblance to the Hallicrafters SR series, particularly the SR-160, which served as the inspiration for this rig.  Accordingly, the PC board in the foreground is a 2017 version of the venerable TO keyer that I'm building to go along with it. N2CQR would approve of the keyer as it uses only discreet components.

Like the SR-160, it is a single conversion SSB & CW transceiver covering the 20, 40 and 80 meter bands.  Unlike the SR-160, it hasn't a single thermionic element, just several dozen transistors and a handful of ICs.

So, why the "SR-16" moniker?  Aside from its obvious derivation from the 55 year old Hallicrafters nomenclature, it also denotes the active devices used in the power amplifier: Two Mitsubishi RD16HHF1 MOSFETs in push-pull.

Pete, N6QW's KWM-4 also served as an inspiration for this rig.  If you haven't visited the web page where he describes it, you should - it's a true work of radio art! 

This has been my most ambitious transceiver project to date (again - that's why I haven't been blogging!) and I'm very pleased with how it's turning out.  The heart of the receiver is the Hybrid Cascode IF strip described in the December, 2007 QST article by Wes Hayward, W7ZOI and Jeff Damm, WA7MLH.  This circuit is really slick, and makes operating the rig a real joy.

In the upcoming days/weeks, I'll go into some details of the circuitry, construction and firmware (Arduino) used in this rig - not to the point of creating a "How To" guide - I'm not qualified to do that - but to maybe give anyone bored enough to read my ramblings some ideas.  There are a few things that I'm doing in this rig that I haven't seen done before that I think are pretty cool - stay tuned.

73 - Steve N8NM


  1. FB Steve. I have a PC board for a Zoi Hybrid Cascode IF strip. You are motivating me to put it to use. It is important to build something different from time to time. 73 keep building AND keep blogging.

  2. Hi Bill,

    The circuit works well for me - I like it! I did find it necessary to shield it, it packs quite a bit of gain and I had a problem with it picking up stray radiation from the BFO.

    I used Pete's mods to optimize the AGC time constant and drive the S-meter - they work great!

    73 - Steve