Charles Spencer's Crystal Radios
Charles Spencer's Junker Radio
If you look close enough you will recognize this as another #44 clone or in this case, mutant. Obviously, I like this circuit. The antenna tuner is a single but beautiful 410pf Hammarlund variable and a 5" basketweave 220uh coil of 175/46 litz. The detector is pure #44 with matching variable and coil.
The two strange looking things poking out the front are 50:1 verniers made from salvaged Ford window motors. They operate smooth as silk and can be rotated so hand position is very relaxed and comfortable. I have hand and wrist problems( read-old, worn out) but I have sat for hours using this radio in comfort. I plan to replace the clear dials with larger ones.
The woods are Zebra and Wenge. This is a large radio at 20"x15" to
balance with the size of the verniers. The detector board is HDPE along
with all couplings and variable bases.
This is no DX assembly but with the improvements I made on my antenna
system, reception is very good.
A simple "Thanks Dave" at this point for your website, encouragement and generosity.
If you call this your junker set, I would probably
fall over seeing your real good ones. :) This is one of those sets when
I opened the e-mail and saw the pictures, I fell back in my chair!
I hope you never tire of making radios.
Thanks so much for the kind response. It feels good that what I think are rather humble efforts got such a response. As with my first radio, seeing it posted on your website chokes me up a little. Feels good.
The Junker took quite a while to build. I kept changing plans as I went, to work around problems that cropped up. I made the verniers first then tried to build the rest to fit. This is a favorite radio but not " the favorite" That one is below and "Quiet Elegance" comes to mind.
The case is made of figured maple a nephew gave me for Xmas. I have a number of Zenith K518 models that gave me the basic idea. The circuit is a combination of Mike Tuggles Mystery Set from the crystalradio.net site and the output section used in a number of your circuits. The size and shape of the case limited the coil type and configuration to the 180uh cylinder of 175/46 litz and positioning of all the components at the angle required.
A unique coupling between the 6:1 vernier from 1n34a.com and the dual 365 pf variable was done with a 1/4" ball end allen wrench turned down and an allen bolt. There is a little backlash slop but tolerable and adjustable.
The dial plates are cd discs with the recording material scraped off. I found that cheap rad/shack Maxell cds can be easily stripped if you first scratch the surface in a small spot. I used a thumbnail to scrape them off.
The radial lines were engraved on the back side in a mill and rotary table then filled with gold lacquer stick. The numbers are gold decals applied then overcoated with clear lacquer.
The mounting brackets are brass and HDPE. The antenna (two different
taps) and ground and the headphone connections are thru disconnects so the
top can be removed without unsoldering or unscrewing connections.
Due to the close proximity of components and the coil tube material this radio does not quite perform like the previous radio. Selectivity is not great but sensitivity is through the roof. It does work very well with an external trap in line.
This radio and the others wouldn't exist had I not come across your site and been awed and inspired by the wealth of information and ideas you share. Thanks.
What can I say, Charles. Another great looking set. You have the touch!
Charles Spencer's Radio
I wanted to email you and let you see the radio I just finished. I had a hard time deciding just what and how to build my first non-kit crystal. I decided your #44 circuit was what I wanted to try but somehow it doesn't look like it much. I went with a one piece base and dovetailed the coil mounts to adjust the coupling. The dials are also a little different. The dials are counters with the 1:6 vernier from you and hooked to gears from a junk clock with a 1:9.75 ratio, so the final ratio is kind of high but works great.
While working on the dials I came up with a number of ideas for home built verniers that should be unusual but work well. I am a mechanic, old mechanic, and a pack rat in addition. I have a number of electric window motors that are worm gear drive and maybe 1:50 ratio. The knobs would be at a 90' to the face but with spacing should work out.
I have a terrible antenna but this set works better than I had expected.
I wanted to say "Thanks a Bunch" for putting all the information and
designs you have on the web and available for anyone to use. Not everyone
is willing to give up hard learned information so openly. Thank You!
Of course you can use the photos. The text is sort of conversation and not very descriptive but that's ok. By the way, the base material is HDPE that I got to use as rip fence lining and router table top. I do quite a lot of hobby wood working and have a supply of exotics but while looking at them and waiting to see a radio face in one of them I glanced at my pile of polyethylene and saw the layout I made. This stuff does scuff easily.
I am glad you like the looks. The coil towers idea is from your friend
in The Netherlands and the dovetails seemed natural to a woodworker.
I could have mounted the components on a circuit board but I wanted all the wiring and components to show. Maybe my next one will be a little neater. I made all the posts and couplings for the dials out of brass. What isn't brass is non-mag. stainless.
I still suffer from information overload but thanks to all the help I
got from your web site the radio does perform way beyond what I expected.
My horrid antenna should be next but I have this idea for.... You have
create a monster. Really, I appreciate the help and interest and by the
way, I have made it through every page on your site; some several times.
Never Bored, Always Fascinated. Thanks again.