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Current Draw on 20M

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Rich-4

Current Draw on 20M

I just received my K3S back from repair and all seemed OK. However it
appears to draw much more current on 20M than any other band. 22 - 24
amps. I have tried two different 20m antennas and a dummy load.

All other bands are 20 amps or lower. Some as low at 17amps.

Power Supply voltage per K3s display 14.0v standby and 13.3 on TX

First off is this actually something of concern?

I hate to do a calibration as it was just done by Elecraft service two
weeks ago.

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Randy Farmer-2

Re: Current Draw on 20M

Mine does exactly the same thing. I even ran it through factory service
to be sure there wasn't a problem with the LPF module that might be
causing trouble. They calibrated it and returned it with a clean bill of
health. It still draws significantly more current on 20 than on any
other band.

73...
Randy, W8FN

On 6/19/2020 8:46 AM, Rich wrote:

> I just received my K3S back from repair and all seemed OK. However it
> appears to draw much more current on 20M than any other band. 22 -
> 24 amps. I have tried two different 20m antennas and a dummy load.
>
> All other bands are 20 amps or lower. Some as low at 17amps.
>
> Power Supply voltage per K3s display 14.0v standby and 13.3 on TX
>
> First off is this actually something of concern?
>
> I hate to do a calibration as it was just done by Elecraft service two
> weeks ago.

Mike Maloney

Re: Current Draw on 20M

FWIW, my old K3 (Nov'08) only pulls 17.8Adc at 12.5V for 100W into 50ohm dummy load at 14MHz.
Seems to follow your PA temp is gonna run hotter also. WHY such poor efficiency Elecraft, (Wayne) ?
73,Mike, AC5P

On Friday, June 19, 2020, 12:03:45 PM CDT, Randy Farmer <[hidden email]> wrote:

Mine does exactly the same thing. I even ran it through factory service
to be sure there wasn't a problem with the LPF module that might be
causing trouble. They calibrated it and returned it with a clean bill of
health. It still draws significantly more current on 20 than on any
other band.

73...
Randy, W8FN

On 6/19/2020 8:46 AM, Rich wrote:

Elecraft mailing list

Re: Current Draw on 20M

After reading your numbers here I was curious since my K3 is the same vintage as yours, serial 732, Apr'08. I did a quick check on 20M and I am reading 15.5A, @13.5V (on my Astron 20M meters) at 100W into a 50 ohm dummy load. I checked other bands and read the following: 160M-15.5A, 75M-14A, 40M-14A, 15M-13.6A, 10M-13A. All readings were in the tune position using a LP-100. I don't think the higher reading on 20 (or 160) is really significant.

Russ, N3CO
Sent from Yahoo Mail on Android

On Fri, Jun 19, 2020 at 1:55 PM, Mike Maloney<[hidden email]> wrote: FWIW, my old K3 (Nov'08) only pulls 17.8Adc at 12.5V for 100W into 50ohm dummy load at 14MHz.
Seems to follow your PA temp is gonna run hotter also. WHY such poor efficiency Elecraft, (Wayne) ?
73,Mike, AC5P

On Friday, June 19, 2020, 12:03:45 PM CDT, Randy Farmer <[hidden email]> wrote:

Mine does exactly the same thing. I even ran it through factory service
to be sure there wasn't a problem with the LPF module that might be
causing trouble. They calibrated it and returned it with a clean bill of
health. It still draws significantly more current on 20 than on any
other band.

73...
Randy, W8FN

On 6/19/2020 8:46 AM, Rich wrote:

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______________________________________________________________
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Randy Farmer-2

Re: Current Draw on 20M

I'm beginning to believe we're up against a harmless component tolerance
stack-up that's peculiar to the K3S lineup design for 20 meters. For
what it's worth, I've done many hours of pretty hard CW contest
operation with my K3S and it hasn't shown the slightest problem
operationally. What originally caused me to notice the 20 meter current
draw phenomenon was that my radio seemed to be shutting down once the
supply current hit about 23A, despite being supplied from an Astron
RS-35 that measured around 12.8V at the radio with key down on 20. I had
attributed the shutdown to the radio, but after it went for the factory
checkout and still produced the same behavior, I swapped the power
supply for its supposedly identical twin that was used for the K3 on the
second station. No more shutdown, so I'm chalking it up to a premature
overcurrent shutdown in the original power supply. Despite the fact that
the radio draws significantly more current on 20 than on other bands,
it's given no indication of any problem since.

73...
Randy, W8FN

On 6/20/2020 1:30 PM, Russ Tobolic wrote:

> After reading your numbers here I was curious since my K3 is the same
> vintage as yours, serial 732, Apr'08. I did a quick check on 20M and
> I am reading 15.5A, @13.5V (on my Astron 20M meters) at 100W into a 50
> ohm dummy load. I checked other bands and read the following:
> 160M-15.5A, 75M-14A, 40M-14A, 15M-13.6A, 10M-13A. All readings were
> in the tune position using a LP-100. I don't think the higher reading
> on 20 (or 160) is really significant.
>
> Russ, N3CO
>
> On Fri, Jun 19, 2020 at 1:55 PM, Mike Maloney
> <[hidden email]> wrote:
> FWIW, my old K3 (Nov'08) only pulls 17.8Adc at 12.5V for 100W into
> 50ohm dummy load at 14MHz.
> Seems to follow your PA temp is gonna run hotter also. WHY such
> poor efficiency Elecraft, (Wayne) ?
> 73,Mike, AC5P
>

Eric Swartz - WA6HHQ

Re: Current Draw on 20M

Administrator

In reply to this post by Rich-4

This is common. Nothing to worry about.

73,

Eric
elecraft.com
_..._

> On Jun 19, 2020, at 5:47 AM, Rich <[hidden email]> wrote:
>
> I just received my K3S back from repair and all seemed OK. However it appears to draw much more current on 20M than any other band. 22 - 24 amps. I have tried two different 20m antennas and a dummy load.
>
> All other bands are 20 amps or lower. Some as low at 17amps.
>
> Power Supply voltage per K3s display 14.0v standby and 13.3 on TX
>
> First off is this actually something of concern?
>
> I hate to do a calibration as it was just done by Elecraft service two weeks ago.
>
>
> ______________________________________________________________
> 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]