[Elecraft] K3/100 and the PSU

[Gary Smith]

I used the included power cable and did notice a drop in the voltage 
of about a volt. I had bought a "35" amp, 25 amp continuous  Astron 
power supply which has variable voltage but does not include a remote 
probe as the one I made from the ARRL handbook offered. The probe was 
used to ID voltage drop and the PS responded by upping the voltage as 
needed so 13.8 would be at the rig at all times.

Using that probe with my old TR7 kept the voltage dead on at the rig. 
I was saddened to have left that in Indiana as a gift to a friend for 
the PS components were made from an old Wang computer I canabalized 
in the 80's and I designed it for an easy 80 amps and it weighed over 
100 pounds and was on casters. It was too much to move and is in use 
today by my friend but I digress;

I felt the best option with the K3 and the Astron VS35M was to use a 
different power cable so I cut the cable aproximately 5" from the 
Power Pole and soldered that short end to an 8 gauge cable made of 
very fine wire which I bought from Home Depot. This was part of heavy 
cable at about $5/foot with four conductors and a heavy neoprene 
outer jacket.

I stripped the jacket, used two of the connectors and attached a 4' 
length to the Astron & k3.
 
>From the K3 internal volt meter it reads: 

14.0V at idle:

At 25W  the drop is .2 = 13.8
At 50W  the drop is .3 = 13.7
At 75W  the drop is .3 = 13.7
At 100W the drop is .4 = 13.6
at 120W the drop is .4 = 13.6

Not as regulated at the rig as my old homebrew PS but certainly a 
very little voltage drop. When running the amp I never use more than 
50W drive so I'm content.

One caveat is I felt the need to devise a mount to keep the power 
cord from moving around behind the radio. I know the PowerPoles are 
loved by many but I see these smaller variety as a weak point and 
don't much like them attached to the rig. The old TenTec attachments 
were not as sexy as these PowerPoles but I felt they had more heft 
and I didn't feel concern that someday the internal soldering would 
come loose from repeated motion as the rig is located from one site 
to another.

Perhaps if the next larger size of PowerPole were utilized I would 
feel it more sturdy? 

73,
GAry
KA1J