Elecraft

KPA100 high current draw

Classic

List

Threaded

5 messages Options

Soaring Eagles

KPA100 high current draw

Folks,

My K2/100 has been working fine for over 6 months. Today I turned it on and
I get a high current draw anytime the KPA100 is inline. Setting power <10
works fine. I haven't even moved the radio since it last worked, so I'm not
sure how to go about troubleshooting.

Thanks for any help!

Jim, WD9HBC
K2 #5757
KX1 #1517

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Don Wilhelm-4

Re: KPA100 high current draw

Jim,

Please differentiate between HI CUR messages and a measured power supply
current to the K2/100. The answer will tell you where to look.

If you are simply seeing HI CUR messages, check the power output from
the KPA100 - if you find that it is putting out max power (100 watts or
greater) for all setting of the power control above 10 watts, then look
for the trouble in the KPA100 wattmeter first. It is quite likely that
diodes D16 and D17 were zapped by a lightning surge (it is summertime
and lightning surges are not uncommon) - if this is the case, just
replacing the diodes will usually cure the problem - and make a mental
memo to disconnect your antennas when not in use.

The HI CUR messages indicate only that the current being drawn by the
base K2 (not the KPA100) is in excess of the setting you have for CAL
CUR. You might want to check the CAL CUR setting - with the KPA100 it
should be set to 3.50 amps or higher.

Another cause of HI CUR messages can be a low voltage from your power
supply - check its output and the connecting cables for good low
resistance connections. The way the K2 controls power results in a
higher current draw when the voltage at the KPA100 (or K2) power
connector is reduced.

If you are having excessive current draw from your power supply (as
measured by an external meter - perhaps on your power supply *and* you
have power control from end to end of the power pot, then you should be
looking at either the T/R switch or the Low Pass Filters in the KPA100
*or* at your antenna and feedline for the problem source.

73,
Don W3FPR

Soaring Eagles wrote:

> Folks,
>
> My K2/100 has been working fine for over 6 months. Today I turned it
> on and I get a high current draw anytime the KPA100 is inline. Setting
> power <10 works fine. I haven't even moved the radio since it last
> worked, so I'm not sure how to go about troubleshooting.
>
> Thanks for any help!
>
> Jim, WD9HBC
> K2 #5757
> KX1 #1517
>

Ron Hahn (EI2JP)

Re: KPA100 high current draw with no power output

In reply to this post by Soaring Eagles

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Colleagues,

I've just finished a KPA100 and am in the process of doing the final
checkout.

I've made it past the bias adjustment stage and the power supply test
stages.

Below 11 watts output (PA switched out) everything seems to work OK.

Setting the power output to 20 watts and pressing tune results in NO
power output and a current draw of approx. 26 amps. Not good.

I checked recent posts regarding this problem but none seem to have the
high current problem associated with no KPA output power.

Suggestions?

Thanks a mil,

Ron

- --
- -=-------------------------o---------------------------=-
Ron Hahn, EI2JP | Grid Square: IO62TG
Rose Hill | Fists: 10883
Rosslare Strand | QRP-ARCI: 12584
County Wexford, IRELAND | K2: 4922
__+__

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.7 (Darwin)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org

iD8DBQFHUxrDyJCeYjZnfkQRAkvbAJ9iHe9PVXg1HCZoxVzRWLCs+1x3ywCfRguC
1JTrn0xszgOQi8f7RslQwLY=
=WKQo
-----END PGP SIGNATURE-----

--
This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Don Wilhelm-4

Re: KPA100 high current draw with no power output

Ron,

How much power is actually being produced? Measure with an external
wattmeter, then look at the bargraph display and see how many bars are
indicated. If there is a lot of power being produced (120 watts or
greater) and the bargraph does not indicate any RF power, you should
look at the wattmeter section of the KPA100 - particularly T4.

If the actual power output is not being reported to the base K2
microprocessor, the base K2 will increase drive in an effort to produce
more power (because it thinks that is no power output).
The solution to that situation is to find the fault in the wattmeter of
the KPA100.

73,
Don W3FPR

Ron Hahn (EI2JP) wrote:

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Colleagues,
>
> I've just finished a KPA100 and am in the process of doing the final
> checkout.
>
> I've made it past the bias adjustment stage and the power supply test
> stages.
>
> Below 11 watts output (PA switched out) everything seems to work OK.
>
> Setting the power output to 20 watts and pressing tune results in NO
> power output and a current draw of approx. 26 amps. Not good.
>
> I checked recent posts regarding this problem but none seem to have the
> high current problem associated with no KPA output power.
>
> Suggestions?
>
> Thanks a mil,
>
> Ron
>
> - --
> - -=-------------------------o---------------------------=-
> Ron Hahn, EI2JP | Grid Square: IO62TG
> Rose Hill | Fists: 10883
> Rosslare Strand | QRP-ARCI: 12584
> County Wexford, IRELAND | K2: 4922
> __+__
>
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.4.7 (Darwin)
> Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org
>
> iD8DBQFHUxrDyJCeYjZnfkQRAkvbAJ9iHe9PVXg1HCZoxVzRWLCs+1x3ywCfRguC
> 1JTrn0xszgOQi8f7RslQwLY=
> =WKQo
> -----END PGP SIGNATURE-----
>
>

k2jrj-elecraft

Re: KPA100 high current draw with no power output

For what it's worth, I accidently transmitted into an open load with my KPA100 and popped the finals. After the accident, the symptoms were exactly as you described, and the high current was about 26 amps. I replaced the finals and things were back to normal. Bad finals out of the box seems very unlikely so I'd first look for shorts in that area, but anything is of course possible.

- Ron, W2RIP (no pun intended :^)

Don Wilhelm <[hidden email]> wrote:
Ron,

How much power is actually being produced? Measure with an external
wattmeter, then look at the bargraph display and see how many bars are
indicated. If there is a lot of power being produced (120 watts or
greater) and the bargraph does not indicate any RF power, you should
look at the wattmeter section of the KPA100 - particularly T4.

If the actual power output is not being reported to the base K2
microprocessor, the base K2 will increase drive in an effort to produce
more power (because it thinks that is no power output).
The solution to that situation is to find the fault in the wattmeter of
the KPA100.

73,
Don W3FPR

Ron Hahn (EI2JP) wrote:

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com