K3S/100 - TX current on 20m

[aj4tf]

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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[Bob McGraw - K4TAX]

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
>
>
>
> --
> Sent from: http://elecraft.365791.n2.nabble.com/
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

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[Bob McGraw - K4TAX]

As indicated on my K3S current display, at a PWR setting of 100 watts,
to a 50 ohm dummy load:

160M = 18.0A

80M = 17.6A

40M =16.0A

30M = 16.4A

20M = 20.2A

17M = 20.2A

15M = 17.0A

12M = 17.7A

10M = 17.0A

6M  = 18.8A

I'd consider these values to be typical and normal.   Actual power
output as indicated on my Bird 43 is a few watts above 100 on all
bands.  This is after a fresh transmit gain calibration.

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
>
>
>
> --
> Sent from: http://elecraft.365791.n2.nabble.com/
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

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