Lon -- I forwarded this through AMPS because your mail server has my
adr blocked.
Begin forwarded message:
From: R. Measures <r@somis.org>
Date: August 18, 2005 9:57:41 AM PDT
To: "Lon W. Cottingham" <k5jv@kingwoodcable.com>
Subject: Re: [Amps] Multi-meter for HL-2200
On Aug 18, 2005, at 8:12 AM, Lon W. Cottingham wrote:
> Richard,
>
> Thanks for the info. I always learn something every time I
> talk
> with you. I really had no idea what the actual DC voltage would be. I
> picked 3,000 because the actual supply voltage is 3,050 with no load.
> If it
> is only 1,100 volts, that is still enough to jump across the open relay
> contacts and wipe out the receiver.
apparently, but I have never measured the OC withstanding V of a stock
SB-220 relay.
> I was not transmitting when this
> happened. The amp was in standby. I suppose the best answer to this
> situation is to use the best quality, RF rated, capacitor that one can
> find
> for the plate blocking cap.
Strange that a 6kV cap would fail at 0-amperes and 3000v.
>
> I had to buy a new SB-220 transformer from Peter Dahl a while
> back.
> His stock replacement has a little more voltage than the original
> HeathKit
> transformer. It is about the same as the HeathKit HL-2200
> transformer. I
> asked him to put a few more turns on the secondary so that I could get
> the
> voltage up enough to run 1500 watts out. He said that he could not do
> this
> because the core was absolutely full. I looked at his wire sizes and
> thought about this a while then asked him to down size one wire size
> on the
> secondary and run that through his computer and see what it would
> give.
> The results looked good. We settled with a secondary that gives 3,600
> VDC
> at no load and right at 3,300 key down with an output of 1,500 watts
> on 14
> MHz and around 1,700 watts on 3.5 MHz. I realize that this is
> much-a-do
> about nothing as the difference between 1,100 watts and 1,500 watts is
> very
> little in Db's ( about 1.3 Db).
Using a tuning pulser, a stock SB-220 will do c. 1550w-pep @ 7MHz with
140w-pep drive. Do you use 8, 450v filter caps with 3600v?
> But, the customers really like it. They
> want to see the watt meter go up. I sell modified SB-220 just as fast
> as I
> can produce them. The problem is finding them at a price that will
> allow a
> profit after all the mods and upgrades are done.
>
> 73 de K5JV
>
> Lon W. Cottingham
> 1110 Golden Bear Ln.
> Kingwood, TX 77339
>
> 281-358-4207
> 281-358-4234 FAX
> 281-795-1335 CELL
>
>
>
Richard L. Measures, AG6K, 805.386.3734. www.somis.org
Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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