[Elecraft] Power Supplies and Voltage drop

[Bob McGraw K4TAX]

One point brought to my attention by Jack Brindle, has to do with the 
indicated voltage on the K3S display.  The manual page 57, ADC REF makes 
it clear as to the calibration procedure and that if the ADC REF is not 
correct, then display values, such as the rig's supply voltage may not 
indicate correctly.

I did check mine and found it to be in slight error.  Once corrected 
specifically following the procedure, things fell in line correctly.    
You will need a DVM to accurately measure the voltage at pin #2 at the 
ACC connector.   This must be done  "*while the ADC REF parameter is 
being viewed in the menu*.".

Hopes this information helps.

73

Bob, K4TAX





On 4/25/2020 10:21 PM, Bob McGraw K4TAX wrote:
> {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