K1 low power output

[Raimon Pardos Fuidio]

For the atton. to Don Wilhelm W3FPR
Dear DonI hope that you enjoyed your holidays!I sent to you days ago a
description of a problem that I have with my K1This is again the
description of my problem:
My K1 serial nr. 493, revision D, with Firmware upgrade Rev. 109, and
with KAT1, has been working flawlessly for some years.
Now, after some months QRT in my shack, I tried it again, and a problem
appeared:
No matter what is the Power Out setting (I can modify output setting),
when transmitting no bars are shown, in Tune mode shows P 0.1, and I
cannot change power output with WPM, Same behaviour connected to a dummy
load.I removed KAT1, (I did not forget the jumper in J2), and the problem
persists.
I sent to you the readings of a Transmit Signal Tracing, which I do not
copy again here, because they were taken without reattaching R36.
After reattaching R36 the problem has changed a little bit, but remains
similar
With KAT1 removed, when power out setting is under 2.1 watts, the power
out reading is the requested one, but when power out setting is over 2.1
watts, power out reading is always 2.1 watts.
 *This was your immediate answer to my request (many thanks for your
prompt replay!)

 **Raimon,

If you have 10 volts RF at the antenna jack and no DC voltage at the
cathode of D15, then you have either a bad D15 or a bad connection at R36
or R37.  In fact, your earlier K1 you had lifted one end of the resistor
R36 when you installed the KAT1, and you must re-attach it when you remove
the KAT1.  It is on the bottom of the board.

If you do have DC voltage at D15, then R4 or R34 could have bad soldering.
In a rare instance, you night find a shorted C43 - check the resistance
to ground from the cathode of D15, it should be close to 100k.

Once you have DC voltage from D15, I believe the power indication and
control will restore themselves to normal.

It is possible that you have a damaged diode in the KAT1 wattmeter -
especially suspect if an antenna was connected during the non-use period.

73,
Don W3FPR **These are the new readigns after reattaching R36.*

After installing a short jumper from the point labeled *DRV *to ground and
setting the power level to 3 watts using the OUT menu entry.:

*Output setting: 3w*

*Output reading 2.1 w*

7. *PRE (premix): *Expected: .04-.09 V (DC). Actual: 0.05

8. *ATTN (TX attenuator): *Expected: .02-.05 V. *Actual: 0.015 (low???)*

9. *OSC (TX 4.915 MHz): *Expected: .01-.04 V. *Actual: 0.008 (low??)**)*

10. *MIX (TX mixer): *Expected: 0.1-0.2 V. Actual: 0.098 (right ???)

11. *BUF (TX buffer): *Expected: 1.5-2.0 V. Actual: 1.588

12. *TR1 (first TX T-R): *Expected: 0.5-1.0 V. Actual: 0.645

13. *BPF (band-pass filter): *Expected: 0.5-1.0 V. Actual: 0.48 (low???)

14. *TR2 (second TX T-R): *Expected: 0.5-1.0 V. Actual: 0.477 (right???)

15. *TR3 (receive signal shunt): *Expected: < .01 V. *Actual:** **0.000
(right???)*

16. Remove the short from *DRV *to ground. Set DMM scale to 20 or 30 V.

17. *DRV (driver): *Expected: 0.9-1.6 V. Actual: 1.62

18. *PA (power amp): *Expected: 10-15 V. Actual: 16.39 (high???)

19. *ANT (low-pass filter): *Expected: 10-12 V. Actual: 10.2

20. Disconnect the RF probe. (The last measurement is DC volts, not RF.)

21. *RFD (RF output detector): *Expected: 1.7-2.0 V. Actual: 1.71


 *R4 does not exist in my revision D and upgrades. In any case it had
worked right without this resistor.*

*I resoldered all connexions of the circuits: RF Ouput Detector, Transmit
Attenuator and Transmit Mixer/Osc.*

*C43 is right, as well as D15.*

*Resistance from cathode of D15 to ground is 98.4 K*

 Where should I look next?

 Concerning the possibility of a damaged diode in the KAT1, I always
disconnect the antennas from my gear when not in use. I know that even so
there is the danger of an static discharge when using it. Braid and center
conductors of the antenna terminal are shorted to ground when not in use.

Is there the possibility that my basic K1 (which now is not working
properly withou the KAT1) was damaged by the KAT1?

Sorry for the long message. I thought that you need all this informstion in
order to be able to help me.

Many thanks in advance

73

Raimon

EA3EZO
______________________________________________________________
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