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Re: [Amps] Vacuum Relay

To: "Vic K2VCO" <k2vco.vic@gmail.com>, <amps@contesting.com>
Subject: Re: [Amps] Vacuum Relay
From: "Paul" <w8aef@q.com>
Date: Sat, 8 Dec 2012 09:56:59 -0700
List-post: <amps@contesting.com">mailto:amps@contesting.com>
I agree that hot switching is most likely the cause of relay failure.

I observed a flakey with one of my radios: when transmitting a continuous carrier the amplifier put out 1500 watts on my p-p wattmeter, when transmitting a continuous string of dots with qsk the amplifier output was about 1400 watts.

Hot switching was the problem.

I use an oscilloscope waveform monitor and it was very obvious on the scope, but for some reason not many hams use a scope as a waveform monitor.

de Paul, W8AEF

ZF2JI/ZF2TA 8Q7AA FO8DX/FO0PLA XZ0A VU7RG/VU3PYM TX5A A52PP


-----Original Message----- From: Vic K2VCO
Sent: Friday, December 07, 2012 1:25 PM
To: amps@contesting.com
Subject: Re: [Amps] Vacuum Relay

I can't suggest a different relay, but I think you should check that there is enough time between the key out circuit closing from your transceiver and the start of RF, as well as making sure that the key out does not open before RF ends. The initial delay should be at least 5 ms. in order to be safe. Relays should last for years, unless they are being
damaged by hot switching.

On 12/6/2012 5:27 PM, Carol Richards wrote:
It looks like I fried another vacuum relay in my Alpha 78 operating it in qsk mode. It is either an HC or RJ type. Can anyone recommend a more sturdy vacuum relay for this amp and where I might get one?



Carol


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