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10th February 2009 11:04
Tomas,
Wow, that is a big variometer. I like the way the rotor is partially spherical so it can be a closer fit with the stator coil, that likely improves the mutual inductance giving it more range. The stepped inner support is a good way of achieving that mechanically - thanks for the picture.
I've never seen a variometer at the local junk rallies. :(
Regards,
Alan
8th February 2009 08:52
There are many variometers on flea markets here in Czech republic, but I like those photos how You construct it on Your own !
Here is photo of "QRO variometer" to You from my dad, for inspiration, he said.. :)
http://web.bxhome.org/image/variometer
6th February 2009 13:43
Arv,
Yes, in fact I have plans to build a shortwave broadcast regenerative receiver using a variometer for both tuning and regeneration coupling control. I recently wrote some PostScript to generate radial vernier scales - might work well with a simple friction reduction drive, like the CD+grommet trick.
One thing I've been meaning to do is plot inductance as a function of angle. I expect it to be S-shaped 'cosiney' and rather non-ideal for nice linear tuning, but that shouldn't matter in practice.
I took the variometer to the recent Homebrew Group meeting and John VK2ASU mentioned the idea of using a similar arrangement as the "swinging link" in a link-coupled tuner. While mechanically somewhat more complicated than the usual swinging link scheme it could be built physically smaller.
Variable interstage coupling sounds very 1920s TRF receiver technology :) Simple way to control the coupling to a tuned circuit though, much more variable than fixed taps and perhaps easier to intuit than tapped-capacitance matching. There is no question that a few moments with the calculator or twiddling a trimmer cap is much more expedient than building the mechanics of the variometer, but for something that needed to be continously variable it might be a good solution.
Regards,
Alan
6th February 2009 08:17
Have you considered a VFO which tunes by variometer?
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Variometer based Antenna Tuner?
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Variometer tuning for transmitter & receiver interstage elements?
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Separate the two coils and use this mechanism for variable link-coupling arrangements?
31st January 2009 06:07
HiHi :)
31st January 2009 04:57
Veri-good!
13th November 2013 00:24
Gene Tomblin wrote...