[Elecraft] Vacuum Relays and 30 WPM QSK

[Chester Alderman]

Aren't PIN diodes still a high power 'pipe dream' for ham applications?? Alpha had only limited success with PIN switching, not because the diodes could not switch at high speeds with power, but way too many hams would test their antenna system with bad SWR, or tune their amp into a load with full power output.. While those PIN diodes could withstand the peak forward voltage at 1500 watts of power, very few of them could withstand the peak reverse voltage when the driven load had high SWR! Because most hams are not "careful" when tuning a high power amplifier, Alpha gave up the better PIN diode RF switch approach in favor of 'fast' mechanical relays. 

I used to run QRQ CW speeds in excess of 60/70 wpm (and faster) with outputs of 1500 watts,, but I had to replace my TenTec Titan amp T/R relay annually! (Never could afford an Alpha amp until recently!)

73,
Tom - W4BQF



-----Original Message-----
From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Dr. William J. Schmidt
Sent: Tuesday, February 28, 2017 1:17 AM
To: jim at audiosystemsgroup.com
Cc: elecraft at mailman.qth.net
Subject: Re: [Elecraft] Vacuum Relays and 30 WPM QSK

Pin diode rf switches are preferred today.  You can even get the QSK-5 kit from Ameritron if you can't make your own.   Good to 2500 watts and infinite speed. 


Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ
 
Owner - Operator
Big Signal Ranch – K9ZC
Staunton, Illinois
 
Owner – Operator
Villa Grand Piton - J68HZ
Soufriere, St. Lucia W.I.
Rent it: www.VillaGrandPiton.com

email:  bill at wjschmidt.com
 

> On Feb 27, 2017, at 10:28 PM, Jim Brown <jim at audiosystemsgroup.com> wrote:
> 
>> On Sun,2/26/2017 3:04 PM, Guy Olinger K2AV wrote:
>> But even though the K3 is cycling TX/RX very fast the 8410 is not 
>> banging the vacuum relay to death trying to follow 30 wpm dits. 30 
>> wpm QSK*does* significantly shorten relay time to failure. 
>> Contesting, I've worn some out in less than a year.
> 
> I own three very nice vintage Ten Tec amps that use vacuum relays. All of them came to me used, and I've replaced those relays in each amp at least once. After a few rounds of that, I stopped running QSK with those amps. :) I'd like to hear from others having experience with vacuum relays and QSK at contesting speeds. I mostly work between 28 and 32 WPM. The original equipment relays were Jennings, and I've mostly used Gigavac as replacements. I haven't had to replace one since giving up on QSK about 8 years ago, but I really would like to run QSK. Have I made the right decision to avoid it when running with a vacuum relay?
> 
> 73, Jim K9YC
> 
> 
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