Thursday, March 26, 2015


     A very long time in coming, I did make progress on the Stancor 10P, getting as far as power supply:

     Rectifier heaters and HV, filter caps, filter choke and bleeder.  It's a little crowded and I struggled to solder the capacitor and resistor to the chassis, even with the big iron.

     That work had it almost done, so tonight I added a few more things:
     Installed output feedthroughs and connected the output, wired up the primary power and the meter.

     Top view:

     Rear view:

     Front view:
     Initial tests -- just power-up, check for excessive current draw, check B+ -- went okay.  Hoping to try more by the weekend.

     Update: Tuned the transmitter up on 40m with a 100 Watt lamp in series, and it made a little power (4:1 balun to a Bird Wattmeter and 50 Ohm load.  Tried it without the lamp and blew the fuse instantly.  So....bigger fuse, and/or 150 and 200W lamps.  Maybe a little Amprobing..

     Update 25 May: Yesterday, I finally brought the transmitter up without a light bulb in series with the 120V AC and it worked. Last time I tried this with the wrong fuse (fast-blow) and it popped immediately -- at which point, I set the transmitter aside for awhile. I didn't have the balun and wattmeter for this test, just a 40W light bulb across the output, which is a bit low-resistance for the link coupling to match to. Plenty more to do but this was a big step.


  1. I wondered how this was coming along.

    Nice to see you're still working on it.

  2. Hey! I have the identical 7175 MHz crystal somewhere. That's a good start, innit?

  3. Alternatively you could have bolted a solder lug, (guess they are still available) and then soldered your resistor/capacitor leads to the lug. If you are worried about conductivity you could solder the lug to the chassis without risking overheating the component. OR if there is room, make a solder puddle using a small butane pencil torch, then remelting the puddle to solder your pre-tinned leads.

  4. Bobbie, nice project!! Love the Stancors. I am running a xtal MOPA, built from out of the 1954 handbook (with the modification of Pi output tuning). Running 5 watts out, xtal controlled on the "Lower Forty". Perhaps I may run into you on 40 some time!

    -de wd4nka

  5. Ah, the old radios are grand. In the last picture I see it has the Grin adjustment in the standard position at bottom far right. Would that modern radios did. Good luck with the rig.

    A little more than 8 minutes of Vimeo video:
    Conrad and The Steamplant

    73, Jim

  6. Neat project.

    An observation, if you haven't had the silk-screening done, you may have another option. Fabricate an aluminum panel to the required size, have it anodized black and then send it off to one of those companies that laser etch control panels. That may give you the look you're looking for and save you the considerable expense of paying for the considerable set-up charge for the screen. The engraver can let you know what file format for the panel artwork you generate from Photoshop or Gimp.

    I love the look of black wrinkle paint and have tried to do it with poor results. The stuff can take months to fully cure and even then will be soft and easily damaged.

    Powder coating companies can do wrinkle and it will likely be far more durable. That may not be an option for you as curing the powdercoat is done in an oven at several hundred degrees, and I doubt the caps and likely other components would survive the roast. Something to possibly keep in mind for a future restoration project when the chassis is fully stripped...

    Loved the article on ribbon transducers. The 'button' connector you mentioned is quite elderly, years back I had an old HP signal generator (long gone now, like an idiot I tossed it 30 years back) and the button connector was used for AM modulation input.

    If you're curious how I stumbled across your blogs, you had made a comment on Paul Thurst's quite cool 'Engineering Radio' blog, being a bit of an RF geek myself, I've been reading as time allows. I believe it was an article on antennae base current measurement.

    Been enjoying your 'Starship" blog, quite clever referring to vhf-uhf broadcast transmitters as a starship drive core...

    The station's GM actually called you on the carpet for the Starship blog? You never directly referred to them!