I'll take both sides of this discussion!
1. The HV is sufficient for proper operation. Remember, these are PIN diodes,
not switching diodes. The wide intrinsic region slows down their switching
speed so RF will pass through--or be blocked. Even momentary voltages/currents
exceeding the biasing level. That's the magic of PIN diodes. Like a relay, they
can carry/block HF, but are limited in how fast they may toggle ON/OFF. But
their toggle speed is a few orders of magnitude faster than a mechanical relay,
of course.
2. The MFJ QSK switches are poorly designed. I have both the internal and
external versions. Both versions have blown up multiple times. Neither has ever
seen even 1500W (maybe 1200 or so). SWR over 1.5:1 at over 1000W exceeds their
capability. I lose the HV switching transistors, not the PIN diodes...
73 de Bob, K6XX
Date: Mon, 13 Jul 2009 22:14:18 -0400
From: "Joe Subich, W4TV" <lists@subich.com>
Subject: Re: [Amps] HV for Ameritron QSK-5PC
To: <philc@texascellnet.com>, "'k5jv'" <k5jv@kingwoodcable.com>, &qu
ot;'Amp
Reflector'" <amps@contesting.com>
Message-ID: <8065C86008A246DC9F7AFEFA0165C460@laptop>
Content-Type: text/plain; charset="us-ascii"
> My stand-alone QSK-5 has a HV of 380 volts.
That's only enough reverse bias for a matched load in a
50 Ohm system. With 2:1 SWR the peak of the RF crest is
almost 800 V (535 - 540V RMS).
73,
... Joe, W4TV
____________________________________________________________
Folding Chairs for Less
Great prices on well-made chairs. Volume discounts. We price match.
http://thirdpartyoffers.juno.com/TGL2131/c?cp=jxJ4T2CGz9w0wFQcJhYelAAAJz3tJSJWHYsOiRS6VBQzj-76AAUAAAAAAAAAAKorHz5bWQdpOv9qXjxxEY3ZGKMmAAAAAA==
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|