[Elecraft] K2/100 with Older tube amp and transverters hooked up.

[Vic Rosenthal]

Paul wrote:

> This amp is an old tube style amplifier with three RCA style
> connectors for
> 
> 1 - Ant. Relay 2 - RF Input 3 - ALC

What kind of amplifier is it?  Although the K2/100 amp control output 
can handle most control circuits (up to +200vdc at 1 amp), some 
amplifiers use negative relay control voltages, AC, etc.  The SB200 
comes to mind as one that has a negative voltage.  You will need to 
modify the amp or use an external relay  to operate the circuit in this 
case.

> On the K2/100 nothing is labeled like this.
> 
> How does one hook up a K2 to this type linear.

Obviously, the RF output of the K2 goes to the amp RF input.  The K2's 
PA Key Out goes to the antenna relay input of the amplifier, assuming 
that the control voltage is DC, positive, and the current is less than 1 
amp.  The K2 does not support ALC input from an amplifier.  You will 
need to adjust the RF output of the K2 so that you do not overdrive the 
amplfier.  To be brutally frank, if you don't understand how to tell if 
you are overdriving the amplifier, you should not use it.

Most older tube amplifiers have slow t/r relays so you will have to 
adjust the K2 T/R time for semi QSK on CW.  You still might have 
hot-switching issues when you go from rx to tx on CW or SSB VOX.

> I do have a high power manual tuner to put in line and I am guessing
> that goes between the amp and the antenna.

Yes.

> I read about Harbach Soft start key - is that used only for CW
> keying? or do I need this for SSB voice too?

Harbach has a 'soft key' to reduce the amount of current and voltage 
needed to operate an amplifier's antenna relay.  This would be 
appropriate for an SB-200, for example.  It would not be needed for most 
amplifiers.  They also have a 'soft start' -- this is to reduce the 
inrush current when turning the amplifier on in order to protect the 
on-off switch, tube filaments, etc.  It doesn't have anything to do with 
  interfacing to the exciter.

-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco