[Elecraft] normal K3 voltage drop on TX

[Joe Subich, W4TV]

On 8/21/2015 11:06 AM, Charles Yahrling wrote:
> What would be a normal value on the FP voltage display when tx at
> 100W, using factory fused cables? No sub installed.

I don't know about "factory fused cables" since my factory cable does
not have fuses.  However, using the stock cable and an Astron RS-35A,
My K3 reads 13.8V in receive, 12.9V in transmit with 17.9A for 105 W
output into a dummy load on 20 meters.

I would be very uncomfortable with an indicated 2V drop under load
as that indicates more than 0.1 Ohm of resistance in connectors,
fuses and cable.

What voltage does the RS-35M front panel meter show under load?  If
it also sags, your problem could be pass transistor or internal
connections (e.g. loose screws on the filter capacitor). If it is
steady, your problem is in the cable/fuses/etc.

73,

   ... Joe, W4TV


On 8/21/2015 11:06 AM, Charles Yahrling wrote:
> What would be a normal value on the FP voltage display when tx at 100W,
> using factory fused cables? No sub installed.
>
> PS is Astron VS-35M linear, voltage set at 13.9 idling per FP display.
> drops to 11.1 on TX.  Current varies but up to 15.5A indicated. Specs call
> for 17-22A tx @100W.
>
> I suspect bad pass transistor and/or high drop over fuses, but want to
> establish normal indication for tx drop.  11.1v seems way out.
>
> tnx in advance
>