EMRFD Message Archive 3244

Message	Date	From	Subject
3244	2009-06-27 20:01:47	Paul Anderson	Wobulator?
My father studied for his electronics technician diploma in the 1960s, and he told me of something he remembered regarding the earliest days of FM. The name he remembered was "wobulator". It varied the output frequency by having a small motor with a crank turn a variable capacitor back and forth. Does anyone remember this device? --- Paul Anderson wackyvorlon@gmail.com http://www.andersonloco.com
3245	2009-06-27 20:21:31	Graham / KE9H	Re: Wobulator?
Some time ago, I purchased a Korean war era airborne radar jammer for parts, that used a "Wobulator." It was a motor driven continuous rotation butterfly capacitor that tuned a power oscillator up and down in frequency as one of its several jamming modes. I am not aware of a civilian use for a wobulator.
3246	2009-06-27 20:31:33	David L. Foreman	Re: Wobulator?
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3247	2009-06-27 22:33:20	kerrypwr	Re: Wobulator?
The wobbulators (note spelling) that I know were sweep generators used mostly to align IFs. I've never seen a mechanical one but I'd heard that they existed. Here is a nice old one; http://www.g1jbg.co.uk/test13.htm I built one from a Practical Wireless article a long long time ago. It had a fairly narrow sweep width centred around 450kHz or so.
3248	2009-06-28 04:48:11	joe price	Re: Wobulator?
3254	2009-06-28 08:36:40	Chris Trask	Re: Wobulator?
> >My father studied for his electronics technician diploma in the >1960s, and he told me of something he remembered regarding the >earliest days of FM. > >The name he remembered was "wobulator". It varied the output >frequency by having a small motor with a crank turn a variable >capacitor back and forth. Does anyone remember this device? > In the second world war, radar jamming was overcome by way of a wobulator that consisted of a gearhead motor with a cam on the shaft. It would rub against the klystron tuning lever to vary the frequency. Chris ,----------------------. High Performance Mixers and / What's all this \ Amplifiers for RF Communications / extinct stuff, anyhow? / \ _______,--------------' Chris Trask / N7ZWY _
3262	2009-06-29 15:09:28	Neil Douglas	Re: Wobulator?
Paul, I remember in the 1960's using wobulators to align TV's. I have used a French Metrix unit this used a small synchronous motor spinning a permanent magnet over a ferrite cored coil. It covered HF through to about 200MHz, I remember using it to align my first 2M convertor made with selected 2N3819's. Other wobulators I used during this period were British ones made by Cossor and Samwell and Hutton both these used electronic tuning. The ultimate alignment aid I used during this period was a Rhode & Schwarz Polyskop - beautifully made and a serious contender as the ultimate boat anchor. NeilD G4SHJ _____
3265	2009-06-30 06:54:50	Dave	Re: Wobulator?