Some QSK amps increase the vacuum relay coil voltage to make it switch
faster -- on the order of 1-2 ms.
73, Dick WC1M
> -----Original Message-----
> From: Tim Duffy K3LR [mailto:k3lr@k3lr.com]
> Sent: Sunday, March 30, 2008 2:15 PM
> To: 'Paul Kelley N1BUG'; 'Amps'
> 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
> http://www.k3lr.com
>
>
> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]
> 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
> > http://www.k3lr.com
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