[Elecraft] Power Supplies and Voltage drop

[Bob McGraw K4TAX]

{I changed the topic for good reason.}    Was " K3S poor CW keying 
further investigation"

Lee brings up a good point with regard to power supply terminals.

If you have one of those power supplies that have the terminals with a 
set screw in the side, you are limited to the number or wires or wire 
size which can be correctly inserted.

Here is what I did to remedy the situation.    I obtained two 10-32 x 2" 
brass screws from the hardware store.  I got 4 nuts, 2 for each screw, 4 
flat washers, 2 for each screw and two wing nuts.   I then cut the head 
off of each screw and filed a flat spot about 1/2 " long and deep enough 
to removed the threads. This modified screw was then inserted into the 
power supply terminal so that the flat spot aligned with the set screw. 
Tighten the set screw.  Then run two of the nuts on the protruding 
screw, just up to the power supply connector, but not tight against it,  
and the second nut against the first to form a jam-nut.  Add a flat 
washer, add all the ring terminals you wish, and then a flat washer and 
finally the wing nut.   Do the same for the other terminal.   Now you 
have plenty of stud length and have not actually modified your power 
supply.  Some fear making modifications for fear of loosing warranty 
coverage.

As a bonus, should you desire to remove the power supply, loosen the set 
screws on the power supply connector and pull out the entire bolt/stud 
assembly, ring terminals and wires, leaving them attached.   Only one 
set screw to loosen removes the entire assembly.  Now how neat is that?

73

Bob, K4TAX


On 4/25/2020 9:50 PM, Leroy Buller wrote:
> Chuck, I am late to this discussion so I might be saying things that
> already been said.  I found the same issue.  Voltage down to 11.5 volts on
> any ps I used.  So, I found the issue was power pole connectors that were
> to light.  Look for power pole connectors that handle 30 amps or so.  Power
> poles come in different amperage with the same shell.  Don't get fooled
> with that.  I did.
>
> Then I limited the cable to 24 inches.  #10 wire and higher current power
> poles.  Voltage dropped fro. 13.8 to 13.1 at 100 watts .
>
> Somebody said that DC systems act significantly to resistance.   Lower the
> resistance to the smallest number is what I tried to do.
>
> Some ps have funky connectors o. The back, and might have to jigger those
> to bolts and nuts.  I opted to use sleeves crimped on the end of the wire,
> soldered, and then stuffed in the connector.   The set screws were replace
> with machine bolts and tighten but you cannot over tighten because the
> threads might strip.
>
>
> Lee K0WA
>
> O