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AIR VARIABLE CAPACITOR KITS

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Vasile Pop VA6POP

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Jan 17, 2014, 1:59:56 AM1/17/14
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10-100pF/5KV HOMEBREW AIR VARIABLE CAPACITOR KITS
for yours KW RF amplifier ,antenna tuner or magnetic loop antenna


The plates are manufactured using a CNC machine
The rotor has 4"OD.
The aluminum spacer are
OD = .500 (1/2") 12.7mm ID = .257 6.53mm L = .500 (1/2") 12.7mm

https://www.youtube.com/watch?v=xISBBh5LK7o

I can build for u any air variable capacitors ,butterfly capacitor,single and split stator capacitor kits,parts

http://www.flickr.com/photos/93005502@N08/page3/
https://www.youtube.com/watch?v=PVGZryuLwQ0

I have also available for ham radio BUTTERFLY CAPACITOR KITS
3" OD ROTOR + 2 STATOR PLATES $ 5.00
4" OD ROTOR + 2 STATOR PLATES $ 6.50
5" OD ROTOR + 2 STATOR PLATES $ 7.75
6" OD ROTOR + 2 STATOR PLATES $ 8.75
8" OD ROTOR + 2 STATOR PLATES $ 10.50
10" OD ROTOR + 2 STATOR PLATES $ 14.00

73 de VA6POP
yo5bzz(at)gmail.com

gareth

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Jan 17, 2014, 6:12:58 AM1/17/14
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"Vasile Pop VA6POP" <yo5...@gmail.com> wrote in message
news:612909ae-0e55-463d...@googlegroups.com...
> 10-100pF/5KV HOMEBREW AIR VARIABLE CAPACITOR KITS
> for yours KW RF amplifier ,antenna tuner or magnetic loop antenna

No need to pay out your shekels!

The June 2013 edition, page 70, of BadCon (The journal of the RSCB)
has an article on how to make your own from old baked bean tins.

Now, I would not normally support the Radio Society for Citizen's Band,
the pit into which the once-proud RSGB has descended, but an article
devoted to the genuine homebrewer is too good to be missed!




Zach Metzinger

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Jan 17, 2014, 3:37:10 PM1/17/14
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You could also dispense with the mechanical capacitor completely and use
a varactor diode tuned by a voltage. I've even seen some designs use a
regular LED reverse-biased in a pinch.

DE N0ZGO

Michael Black

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Jan 17, 2014, 5:00:07 PM1/17/14
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There's lots of alternatives. One could use a permability tuned
oscillator. Use broad band sections (though preferably segments that
cover a full band rather than no filtering at all), so you just switch
filter sections as you move to the next band.

At this point in time, they aren't as handy as when you could easily fined
radios with variable capacitors, but there are still a lot of low value
low voltage variable capacitors out there. Probably more than enough for
most low level circuitry.

But, there will always be a time when you can't come up with an
alternative. High voltage variables for transmitting loops, or output
circuitry in a transmitter. Varactors won't work in that situation.

And that's when you'll need to make variable capacitors. At the best of
time those weren't readily available (likely requiring a special order)
and were relatively expensive. Now, they are outright expensive, if you
can find them.

Michael VE2BVW

Bill M

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Jan 17, 2014, 6:07:08 PM1/17/14
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A 5kv RF circuit presents some additional challenges!

-Bill

philo

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Jan 17, 2014, 6:09:52 PM1/17/14
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Yep!!!!

Michael Black

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Jan 17, 2014, 7:08:11 PM1/17/14
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That's where those beer bottle capacitors come in.

Michael

gareth

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Jan 18, 2014, 11:30:16 AM1/18/14
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"Zach Metzinger" <zmet...@pobox.invalid> wrote in message
news:lbc49o$nc4$1...@dont-email.me...
Hardly. Not for TX tuning.


Michael Black

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Jan 18, 2014, 10:58:24 PM1/18/14
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But remember when there were no-tune broadband rigs? The Central
Electronics exiter in the fifties, but then in the seventies with solid
state, the Heathkit SB104. Though, I can't remember if they had a
tuneable pi network output.

But I seem to recall the SB104 getting all kinds of press, and then people
noticing that there was nothing to tune, so they'd have to add an antenna
tuner to match things up.

Michael

Zach Metzinger

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Jan 23, 2014, 12:59:19 PM1/23/14
to
On 01/17/14 16:00, Michael Black wrote:
> On Fri, 17 Jan 2014, Zach Metzinger wrote:
>>
>> You could also dispense with the mechanical capacitor completely and
>> use a varactor diode tuned by a voltage. I've even seen some designs
>> use a regular LED reverse-biased in a pinch.
>
> But, there will always be a time when you can't come up with an
> alternative. High voltage variables for transmitting loops, or output
> circuitry in a transmitter. Varactors won't work in that situation.
>
> And that's when you'll need to make variable capacitors. At the best of
> time those weren't readily available (likely requiring a special order)
> and were relatively expensive. Now, they are outright expensive, if you
> can find them.
>
> Michael VE2BVW

Michael-

Excellent point, and I sit corrected. I need to read more closely next time!

DE N0ZGO
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