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Author Topic: 365-400pf variable caps...source?  (Read 4303 times)
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ve6pg
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« on: June 07, 2012, 07:29:48 AM »
..built a small loop, for 75m, but cant seem to find a small enough variable cap for peaking the receive...yrs ago, there were "transistor" radios all over...nice small cap...cant find anything these days...ideas?..

..sk..
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...Yes, my name is Tim Smith...sk..
W3GMS
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« Reply #1 on: June 07, 2012, 08:38:18 AM »
SK,
I thought Antique Electronic Supply still carried the multi-section BC variables.  Also look at Fair Radio since they in the past have had some.   

If you have a smaller air variable just use a silver mica to pad it to get to your desired capacitance.  That way you would have a nice vernier type of control.

Have fun....
Joe, W3GMS 
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Simplicity is the Elegance of Design---W3GMS
N4LTA
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« Reply #2 on: June 07, 2012, 09:17:47 AM »
The Crystal Set Society has many available.

http://www.midnightscience.com/catalog5.html


Pat
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W4AMV
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« Reply #3 on: June 07, 2012, 09:54:41 AM »
Consider the varactor MVAM1401. I believe it will tune 400 pF-to- 10 pF with a modest voltage change. The Q is quite reasonable but certainly not the same as the air variable.
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KM1H
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« Reply #4 on: June 07, 2012, 12:53:59 PM »
Ebay is full of them
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KD7EDW
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« Reply #5 on: June 11, 2012, 12:19:00 AM »
Mike Peebles at Peebles originals has a 15-410 pf unit that is very nice.   

http://www.peeblesoriginals.com
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"You never change things by fighting the existing reality. To change something, build a new model that makes the existing model obsolete."

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W3RSW
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Rick & "Roosevelt"
« Reply #6 on: June 13, 2012, 08:14:23 PM »
Also Dans small parts and kits. $14 for the exact dual used in the Ocean Hopper and numerous all Amer. 5's.
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RICK  *W3RSW*
ve6pg
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« Reply #7 on: June 13, 2012, 09:55:32 PM »
..what i'm looking for, is one of those small postage stamp sized ones that went into transistor radios...dont see those things around anymore...
..tim..

..sk..
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...Yes, my name is Tim Smith...sk..
AL7FS
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« Reply #8 on: June 13, 2012, 10:54:41 PM »
I have no experience with what you are doing so if this is not the right thing, please don't laugh.  :-)

http://www.qrpkits.com/polyvaricons.html

These only go to 220pf, though.

Jim Larsen, AL7FS
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W4AAB
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« Reply #9 on: June 14, 2012, 08:49:15 PM »
To get something robust(unlike the transistor radio caps), look for some ARCO compression trimmer caps.
                                            Joe W4AAB
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