To: rsgb_lf_group@blacksheep.org References: <000c01c61955$de2ddce0$6401a8c0@JAYTERMINAL> <000b01c61969$5f7b1480$86327ad5@w4o8m9> <001101c619ae$436c1b00$ef497ad5@w4o8m9> <000f01c619ec$264266e0$0be9fc3e@l8p8y6> Date: Sun, 15 Jan 2006 16:35:00 -0800 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Subject: LF: Re: Re: Re: TA Content-Type: text/html; charset=windows-1252 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-PN-SpamFiltered: by PlusNet MXCore (v2.00) Content-transfer-encoding: 8bit

Quoting Mal...

"This QRS business is severe on PA fets and some psu's, especially the slower crawls. Anything beyond QRS 3 - 10 could be fatal over long periods for most rigs. Any sudden antenna instability, windy condx, showers then sunshine ie SWR variations are tricky at the vy slow speeds, even the Decca Jeeps have been know to blow smoke in amateur applications."

I don't buy that at all.

My station has run 24/7 for extended periods at max power with a floppy vertical to deal with the 'Pacific breeze' and rarely if ever have I lost a FET and never a power supply... All my FET failures can be classed as operator error not environmental factors... My only FET death this year was caused by arcing to my nearby 80m dipole. It arced for a good 30minutes by the look of the grab I was sent and then one of the FETs in the TX shorted...

The trick is ensuring good cooling and sizing of the parts, particularly ferrites. If there is a danger to the FETs its when you're doing that old switched carrier mode rather rapidly and only if you haven't taken good care of the transients on the FET drains ;-)

Sorry Mal but my observations during prolonged and rapid weather changes don't indicate that amateur transmitters are so delicate that they can't handle long QRSS dot modes... I've run my sinewave (QRSS near-infinity) for weeks on end without trouble during all kinds of weather events...

I have data if you want to see it...

Scott