[Elecraft] K3 external qro keying line

[Guy Olinger, K2AV]

The sentence does not fix whether the relay is in the amplifier or in the 
K3.  Perhaps:

"...is transistor output for keying amplifier T-R circuits, ONLY positive 
voltages up to +200VDC @ 5A."

Could a future mod include a blocking diode for negative keying voltages if 
the circuit will not sink high negative voltages without damage.

73, Guy.

----- Original Message ----- 
From: "John Lemay" <john at carltonhouse.eclipse.co.uk>
To: "'Tom Hammond'" <n0ss at embarqmail.com>; "'Lee Buller'" <k0wa at swbell.net>; 
"'Elecraft Reflector'" <elecraft at mailman.qth.net>
Sent: Friday, February 13, 2009 5:54 AM
Subject: Re: [Elecraft] K3 external qro keying line


>I can see reason for confusion here - the K3 Manual on page 17 describes 
>the
> "amplifier T-R relay keying output ...."
>
> Maybe the wording could be clarified. I would certainly form a (incorrect)
> picture in my mind of a small power relay, for which + or -ve switching
> would be permissible.
>
> John G4ZTR
>
>
> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Tom Hammond
> Sent: 12 February 2009 17:19
> To: Lee Buller; Elecraft Reflector
> Subject: Re: [Elecraft] K3 external qro keying line
>
> The K3's T-R line output ("KEY OUT") can switch up to 200VDC @ 5A... so it
> will
> easily switch the +120VDC @ 15-30mA from the SB-220.
>
> However, it will NOT SWITCH a NEGATIVE T-R line voltage UNDER ANY
> CIRCUMSTANCES!
> Users with amps which offer a negative T-R line control voltage will have 
> to
> provide alternate switching (relay, or solid state).
>
> 73,
>
> Tom   N0SS
>
>>phones, mic,
>>line in, and line out
>
>
> At 10:13 02/12/2009, Lee Buller wrote:
>
>
>>HMMMM....  I thought the transistor on the K3 doing the switching is
>>pretty tough.  I guess we are talking about older amps and not the
>>ones that use 12 volts to switch.
>>
>>I have done the following to....  Radio Shack sells a 5v reed relay
>>that is pretty darn fast and has good specs.  I just used a dropping
>>resistor from a 12 volt line in series with the reed relay and
>>worked great for years.  I think I used a 180 ohm resistor.  Worked
>>great.  Not QSK, but I don't like QSK anyway.  Messes with my head.  HI
>>
>>Lee Buller - K0WA
>>
>>
>>
>>In our day and age it seems that Common Sense is in short supply. If
>>you don't have any Common Sense - get some Common Sense and use it.
>>If you can't find any Common Sense, ask for help from somebody who
>>has some Common Sense. Is Common Sense divine?
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