Re: K3S/100 - TX current on 20m

Posted by Bob McGraw - K4TAX on Nov 11, 2019; 1:48pm
URL: http://elecraft.85.s1.nabble.com/K3S-100-TX-current-on-20m-tp7656371p7656374.html

Measurements on my K3S into a 50 ohm load, at 100 watts PWR setting did
show the current does vary from band to  band.  I found that 20M and 17M
were the highest at 20.2 amps as indicated by the current display in the
K3S.  The lowest current was 16.0 amps on 40M.   I would consider this
to be normal and of no concern.

73

Bob, K4TAX

On 11/11/2019 4:29 AM, aj4tf wrote:

> Something that I have recently noticed on my K3S/100 :  DC current draw on 20
> meters is significantly higher (+4 amps) than the other HF bands at the same
> power setting and input conditions into a dummy load (into antenna, same
> thing).   This is both before and after performing a TX Gain Cal.
>
> Test conditions:  mode Data A,  input single test tone from FLDIGI software
> (4-5 bars ALC), tone level & frequency not changed during the tests, ATU
> bypassed, ANT1 selected.  Power supply voltage in RX,  14.3 V,  RX current
> 1.2 - 1.3 amps.
>
> This ONLY occurs on 20m, the other HF bands seem to be OK. (6m is higher
> than the HF bands by about 2 amps, not sure if that is normal or not).   For
> example, with 80W out: 80m, 60m, 40m, 30m, 17m, 15m, 12m, 10m are all close
> to 16 amps, but 20m is 20 amps.  (6m is 18 amps).
>
> I searched the archive and found a few references to "bad low pass filter".
> I have already emailed details to [hidden email] but wondered if there
> is something I can check in the meantime until they get back to me.
>
> 73 David AJ4TF
>
>
>
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