[AMPS] Roller Inductors vs. Bandswitches ... which is best?

[Walter Dail]

Theo,
  I'd like to see the info posted to the reflector. It would be good to
consider the
pros and cons of a roller. I've been contemplating the same thing. I've got
a roller in my Johnson Thunderbolt and it works OK. I guess as long as the
inductor can handle the power and is cooled (at high freqs) it shouldn't be
a problem.

73,
Walter KT4JA

----- Original Message -----
From: "K4MO" <K4MO@carolina.rr.com>
To: <amps@contesting.com>
Sent: Tuesday, February 06, 2001 5:55 PM
Subject: [AMPS] Roller Inductors vs. Bandswitches ... which is best?


>
> I have just about collected all the parts to build my next project and I
> will soon be faced with the decision of how to switch bands with the final
> tank circuit. I see three options:
>
> 1. Use the EF Johnson 222-101 variable inductor that I've been saving for
> the last few years. I used a roller in my last large amp, chiefly do to
the
> fact that I had it and it saved all the trouble of fiddling with taps and
> such.
>
> 2. Use a big strap wound inductor and large ceramic switch. I have the
coil,
> but will need to locate a switch.
>
> 3. Use the aforementioned coil but switch it with relays, which I would
> still need to procure. This offers the advantage of being able to remote
> control the band change at some point in the future.
>
> I am hoping some of the more experienced builders can offer some opinions
> and suggestions regarding the technical merits or shortcomings of these
> three choices. Is one method or the other more subject to random parasitic
> oscillations? Is tank circuit heating more of an issue with one or the
> others? What other considerations do I need to ponder in this regard?
>
> I have looked through most of the archives and could find no previous
> discussion on Rollers verses Switches so any and all thoughts and ideas
are
> welcome.
>
> Thanks & 73,
> Theo - K4MO
> www.qsl.net/k4mo
>
>
>
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>


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