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Re: [Amps] Relays

To: <>, "'Paul Kelley N1BUG'" <>, "'Amps'" <>
Subject: Re: [Amps] Relays
From: "jeremy-ca" <>
Date: Sun, 30 Mar 2008 16:25:58 -0400
List-post: <">>
" As you point out, radio + amplifier "handshaking is important"

That is what Ive suspected all along but havent verified the timing. Once 
replaced when time matters it sort of gets ignored for a few years until it 
happens again.

The Amp Supply uses a DIP relay for the input and the RJ-1A at the output. 
The TS-940 is vox keyed on CW at the point the first dit isnt lost or 
truncated. Thats as deep as Ive gone. The rig is an antique compared what is 
in use today but Ive got no interest in contesting any more either.

Lifes too short to waste weekends in front of a radio ignoring famly, 
chores, other interests, etc.

With customer amps I never dug into the details since they were either in a 
hurry, didnt know, or didnt care.

Amplifier repairs, modifications and 6M conversions since 1964

----- Original Message ----- 
From: "Tim Duffy K3LR" <>
To: "'Paul Kelley N1BUG'" <>; "'Amps'" 
Sent: Sunday, March 30, 2008 2:14 PM
Subject: Re: [Amps] Relays

> Hello Paul!
> The rig delay of only 3 Ms could be a real problem.
> We never run QSK, so I am sure that helps prolong the life of the relays 
> in
> use at K3LR. The K3LR Icom radios and computer CW keyers and voice keyers
> all have small delays that allow the amplifier relays to close properly
> before RF is applied, so I am sure that helps as well.
> As you point out, radio + amplifier "handshaking is important.
> 73!
> Tim K3LR
> -----Original Message-----
> From: [] On
> Behalf Of Paul Kelley N1BUG
> Sent: Sunday, March 30, 2008 1:10 PM
> To: 'Amps'
> Subject: Re: [Amps] Relays
> Thanks Tim,
> That is reassuring. I have been using RJ1A relays in my HF single
> 4CX1500B for some time and have yet to experience a failure. I run
> QSK CW frequently. I am also using them on my new 6m 4CX1500B amp
> where I realize I'm probably pushing my luck... time will tell.
> Recently I was asked to repair an amp using RJ1A relays that had
> suffered contact failures. It wasn't all that much power, about 1
> kW. I became curious as to why the relays had failed. The owner had
> controlled the amp by a simple cable from the rig's amp T/R control
> line to the amp. Unfortunately that rig only had a delay around 3 ms
> after closure of the amp T/R contacts to the start of RF output in
> both CW and SSB. The new RJ1A relays I installed needed 5 ms
> (measured) to close and stop bouncing, so they would be hot switched
> by that setup. Not good. I wonder if this sort of thing might
> explain some of the vacuum relay failures we hear about?
> I would add that fast relays can in some cases actually be slowed
> down by the nature of the power supply or the circuit controlling
> them. I always verify actual timing of the relays in an amp with the
> RF output delay of the radio(s) it is to be used with unless there
> is provision for 'RF hold off' handshaking between the amp and
> transceiver.
> 73,
> Paul N1BUG
> Tim Duffy K3LR wrote:
>> I have been using single Kilovac HC-1 and Jennings RJ1A relays for input
> and
>> output T/R switching on all of my single 8877 amplifiers for the past 25
>> years.
>> Even in heavy contest operating, I have had no problems at 1500 watts
> output
>> up through 50 MHz.
>> 73!
>> Tim K3LR
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