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Title: Reproduction Lettine VFO and Tuner Post by: n4joy on March 17, 2019, 12:21:04 PM I am a collector of all things Lettine but have never been able to locate a Lettine VFO and tuner. Only some pictures exist on LA5KI's website. I decided to use schematics from Bama and scant photos to make my own. Other than a Zener on the CT to drop B+ to 300V under load, I followed the schematic exactly.
The VFO is based on a Clapp oscillator and uses a 5763, two OB2 VR tubes, and a 5Y3. I used chassis punches and step bits for the hole punching. The cabinets are Bud and were powder coated with "gun metal" wrinkle to duplicate the painted wrinkle finish. After a 30 minute warm-up, drift is about 20hz per minute (Tung-Sol 5763). I just used regular silver micas and the drift is okay for AM work. Interestingly, the first 5763 tube I used (unknown manufacturer) provided a drift of almost 150hz per minute! I didn't realize there could be such a difference between manufacturers! Here are the photos of the original units and next are my finished products. The cabinets are larger than they should be but these were on sale and CHEAP! Title: Re: Reproduction Lettine VFO and Tuner Post by: n4joy on March 17, 2019, 12:22:17 PM Here are some moire photos of the construction. I love step bits!
Title: Re: Reproduction Lettine VFO and Tuner Post by: n4joy on March 17, 2019, 12:25:56 PM And some more... next project is to create labels, which will likely be the most difficult part of the project!
Title: Re: Reproduction Lettine VFO and Tuner Post by: KA0HCP on March 18, 2019, 04:05:02 PM Very nice! I was researching something last month in the early 50's and came across the Lettine ads again, renewing my curiosity. For being advertised so prominently for several years, we don't hear much about them these days. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
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