Multi Tech, formerly Radio Switch Corp, will build you a Type 86 switch to
your hearts desire. And a lot cheaper than a litter of vacuum relays.
Carl
KM1H
----- Original Message -----
From: "Rex Lint" <rex@lint.mv.com>
To: "'Paul Kraemer'" <elespe@lisco.com>; "Amps" <amps@contesting.com>
Sent: Saturday, March 13, 2010 4:36 PM
Subject: Re: [Amps] Revamping a really ugly amp
A variable inductor makes band changes too slow in contests (unless I make 6
amps!)
-Rex-
K1HI
Rex Lint
Merrimack, NH
-----Original Message-----
From: Paul Kraemer [mailto:elespe@lisco.com]
Sent: Saturday, March 13, 2010 3:34 PM
To: Rex Lint
Subject: Re: [Amps] Revamping a really ugly amp
Rex
I would keep the variable inductor as it represents an ideal situation for
an all band all mode amp, IMHO
In power rf smaller may not be better, IMHO
If I were going to use relays they would be vacuum type as are used in
commercial designs. I've seen it done at Collins Rockwell .
Paul K0UYA
----- Original Message -----
From: "Rex Lint" <rex@lint.mv.com>
To: "Amps" <amps@contesting.com>
Sent: Saturday, March 13, 2010 1:04 PM
Subject: [Amps] Revamping a really ugly amp
>I bought an old H/B amp that I'm totally revamping.
>
> It's 2 x 3-500Z's with a 4KV power supply. It USED to have a pi-network
> with a vacuum variable plate capacitor and a regular variable loading
> capacitor, and the tank coil *was* a variable inductor so that the tank
> could be adjusted for any transformation (within reason). I want to keep
> the caps, but change the coil to discrete inductor(s) with taps.
>
> I wonder if anyone uses relays instead of a rotary switch to select the
> desired taps? What are the parameters I need to consider in trying this?
> In my thinking, I'll just be switching the output side of the inductor,
> and
> the impedance at this point (when tuned) should be about 50 ohms, so the
> voltage isn't that high (350 V.?), and the current would be about 6 amps.
> Relays for this should be a dime (well, $20) a dozen? As a mtter of fact,
> I
> see one like this would handle the job if never switched "hot" which you
> wouldn't want to do with a rotary switch either!
> http://www.mv.com/ipusers/lint/K1HI/RelaySpecs.pdf
>
> I'm also looking at compact tank coils in the literature. How much power
> could I expect to run with two muffin fans to cool the tubess and
> operating
> CW contests?
>
> Thoughts?
>
> -Rex-
>
> Rex Lint, Consultant
> 26 Brek Drive
> Merrimack, NH 03054
> PH: 603-860-7651
>
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
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