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Title: German Silver and HRO Dials (was Timonium Countdown) Post by: k4kyv on March 28, 2008, 01:59:07 PM I am posting this by starting a new thread, because the topic has strayed pretty far from the Timonium Countdown. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
I'm not sure that was german silver. I think that was actual silverplate, over what I dont know. I've never seen a early HRO with the silver dial, just the pictures. German silver name for various alloys of copper, zinc, and nickel, sometimes also containing lead and tin... German silver varies in composition, the percentage of the three elements ranging approximately as follows: copper, from 50% to 61.6%; zinc, from 19% to 17.2%; nickel, from 30% to 21.1%... German silver is extensively used because of its hardness, toughness, and resistance to corrosion... It was discovered (early 19th cent.) by a German industrial chemist, E. A. Geitner. The hallicrafters dial is almost certainly german silver of some type. it takes a lot to corrode or stain them, and they dont tarnish, because there's no silver to tarnish. I was always under the impression that German silver has zero silver content. The reason I am assuming that the early HRO dial is German silver is because James Millen said so. National company used to run an ad in QST every month during the 30's and possibly for a while after WW2, that was a hybrid technical article /sales pitch, usually signed by James Millen himself. I recall reading the episode where he explained why the dial was changed from what he described as German Silver, to black enamel. I believe the dial is actually pot metal plated with German silver, but I may be wrong. It's been years since I had the dial off mine to see what the back side looks like. The dial does tarnish if the receiver has set aside for a long period of time without use - so much for the claim that German silver is highly corrosion resistant, if in fact that is what the dial is really made of. It doesn't turn dark like real silver, but the bright sheen goes away, obscured by a thin layer of dusty oxide. Lightly polishing with a soft cloth completely restores it. I once acquired one of those receivers from a want-ad, and the seller thought he was doing me a good turn by "polishing up" the dial - using a super fine grit emery cloth! He did manage to shine up the dial OK, by removing all the oxide coating, along with a good bit of the dial calibration markings! The kind of "assistance" I could have really done without. Ever since that incident, if I run across a piece of vintage gear that I want to restore, I always immediately instruct the seller to send it to me exactly as is, and not attempt to "clean it up" first. Besides, sometimes the patina on certain old pieces adds class the original more bland pristine finish. The later HRO silvery dials, used on the HRO-50 and 60, have a totally different kind of plating, more closely resembling chrome or pure nickel than silver. The numbers on the plate behind the little windows on those dials are still painted white over a black enamel background - probably to make them more visible in the shadow cast by the front plate of the dial. |