[Elecraft] Connecting my Elecraft K3 to a Drake L-7 amp.

[Jim Wiley]

Jerry -


The VOX connector is the transmit enable connection (PTT).  The AGC 
connection is for rigs that accept external ALC, and may not be needed 
with the K3.  Normal drive for full output is when 240 mA of grid 
current is indicated when fully loaded. 


Use the SSB setting on the plate switch for both CW and SSB.  The lower 
voltage / lower power setting is from when we were limited to 1000 watts 
CW input, 2000 watts PEP for SSB.  The amp will make about 1300 watts 
(low bands) to 900 or 1000 watts (10 meters) if you have good tubes. 


Simple adjustment procedure:  watch the power output, tune for max using 
the plate and load controls.  The panel markings will get you close 
enough to start.  Recheck the grid drive to make sure you are not 
exceeding 240 mA and you are good to go.   


Both the tubes and the power supply are very forgiving, so temporary 
overloads will be well tolerated.    I have used both the L7 and its 
earlier cousin, the L4B, for many years,. and never had a problem, even 
when running full-blast key-down modes like RTTY.  


You may wish to make a mod to the fan circuit to keep the blower turning 
about half-speed at all times, instead of depending on the thermal relay 
to start the fan when the amp is getting too hot.  Simply wire a 300-ohm 
/ 25-watt resistor across the thermal switch to accomplish this.  The 
fan will still go to full speed if needed, but mush less often, and the 
amp will last much longer.  


Be sure to observe normal safety precautions when working inside the 
cabinet - disconnect the power completely, both from the wall outlet and 
the PS from the amp, including the HV connection before opening the 
cabinet. 


- Jim, KL7CC

. 

Jerry Dwyer wrote:
> I just got a good deal on a very clean Drake L-7 amp (2- 3-500Z tubes). I
> was hoping someone might know how to connect them together. The amp has the
> normal RF in and out connectors. It also has two rca connectors, one says
> VOX and the other says AGC. 
>
>  
>
> Thanks for any help
>
>  
>
> Jerry - NF9L
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>