Anyone have a HVSD15K diode they would part with at a reasonable price. I
have a Henry 2000D HV supply with half a section shorted in one of the
diodes.
Thanks,
Jerry W0ZD.
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
Behalf Of la7sl Nils Petter
Sent: Saturday, March 13, 2010 4:26 PM
To: amps@contesting.com
Subject: [Amps] Fw: Revamping a really ugly amp
----- Original Message -----
From: "la7sl Nils Petter" <la7sl@norgespost.no>
To: "Dave White" <mausoptik@btinternet.com>
Sent: Saturday, March 13, 2010 10:21 PM
Subject: Re: [Amps] Revamping a really ugly amp
> Hmmm....
> a stepmotor, a controller and a rotary switch is a better idea !!
> (remove that "click" thing :-) )
> And probably less expensive....
> I would not try cheap relays !!
> Vacuum could work...but would be very expensive at the required
> voltage and current ratings.
> A stepmotor, controller and roller inductor is also good...
>
> ----- Original Message -----
> From: "Dave White" <mausoptik@btinternet.com>
> To: "Rex Lint" <rex@lint.mv.com>; "Amps" <amps@contesting.com>
> Sent: Saturday, March 13, 2010 10:02 PM
> Subject: Re: [Amps] Revamping a really ugly amp
>
>
>> The only amp I've seen that used relays for tank coil switching was on
>> the fleamarket at Friedrichshafen one year. I think it was built by a
>> Hungarian guy and used Russian vacuum relays.
>>
>> I can't particularly think of a reason why you couldn't make this work,
>> though someone may correct me.
>>
>> On 10m in particular there can be a higher Q and thus consequently high
>> circulating currents, so you'd have to ensure enough current handling
>> capacity I can't remember what bands the Hungarian amp worked on, nor
>> the chap's callsign.
>>
>> I do ask the question, however: if it's a piece of cake, how come no-one
>> else does this?
>>
>> Good question, though - and one I've asked myself a few times!
>>
>> Dave G0OIL
>>
>> -----Original Message-----
>> From: "Rex Lint" <rex@lint.mv.com>
>> To: "Amps" <amps@contesting.com>
>> Sent: 13/03/2010 20:04
>> 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
>>
>>
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>
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