K2 Test 2 OK, Test 3 power output problem

[Jukka Tarvainen (OH4MFA)]

Hi!

I got to test and alignment part 2 last friday. Everything went according
to the test procedure. 40 m RX worked well and I spent some time well into
saturday night listening band with wire hanging from my balcony. It was
quite amazing to hear stations with something I put together myself. Thanks
to the great instruction manual!

In sunday assembly part 3 was finished and I went on with test and alignment
part 3. When I set 2 W and hit TUNE the power displayed stays 0.2-0.3 No
change when adjusting L1 and L2. There is quite good peak when adjusting
for RX, so I believe BPF is OK. I have been looking for bad solder joints
in transformers and LPF. Already did again 40 m LPF toroids. There is some
attenuation in the middle on 40 m lpf (crossing of L25, L26, C226, C228
and C229) when doing cheap and dirty signal tracing. Is it normal or may
I have some problem there? Bad cap? All bands RX seem to be ok, but same
power problem on all.

I will check all parts once again and do voltage checks as per troubleshooting.
Any other ideas? I don't have access to test equipment, only DMM, XG1 and
N-gen. I sent e-mail to Elecraft support already, so I believe I get information
from there too.

73 de
Jukka OH4MFA
K2 #4293
Jukka O. Tarvainen, OH4MFA
-[hidden email]
-[hidden email]

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[Don Wilhelm-2]

Jukka,

I suggest you build the RF Probe provided with the K2 kit.  Use the probe
and your DMM to determine where the RF is being lost.

In transmit mode (TUNE), you should find RF in ever increasing levels at the
following points:
TP1,
Xmit Mixer - U10 pin 4
Xmit Buffer - U9 pin 6 (and input to the BPF - junction of D6 and D7 cathode
ends)
Pre-Driver - Q5 collector
Driver - Q6 Collector
PA Output - Q6 and Q7 collectors
Low Pass Filter input and LPF output.

73,
Don W3FPR


----- Original Message -----

I got to test and alignment part 2 last friday. Everything went according
to the test procedure. 40 m RX worked well and I spent some time well into
saturday night listening band with wire hanging from my balcony. It was
quite amazing to hear stations with something I put together myself. Thanks
to the great instruction manual!

In sunday assembly part 3 was finished and I went on with test and alignment
part 3. When I set 2 W and hit TUNE the power displayed stays 0.2-0.3 No
change when adjusting L1 and L2. There is quite good peak when adjusting
for RX, so I believe BPF is OK. I have been looking for bad solder joints
in transformers and LPF. Already did again 40 m LPF toroids. There is some
attenuation in the middle on 40 m lpf (crossing of L25, L26, C226, C228
and C229) when doing cheap and dirty signal tracing. Is it normal or may
I have some problem there? Bad cap? All bands RX seem to be ok, but same
power problem on all.

I will check all parts once again and do voltage checks as per
troubleshooting.
Any other ideas? I don't have access to test equipment, only DMM, XG1 and
N-gen. I sent e-mail to Elecraft support already, so I believe I get
information
from there too.



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[Jukka Tarvainen (OH4MFA)]

Hi Don and Elecrafters!

I built RF-probe already and have done some measurements. I will look into
these measuremnts which Don recommended afterwards.

I did some DC-voltage checks last night. These are things I found to be
off in RX mode. Power supply about 12.5 VDC:

Control board (front panel removed)
U6 P18 5 V (should be 0 V)
U9 P1 0 V (should be 0.4* V)
U10 P1 0.07 V (should be 7.7* V)
    P2 0.01 V (should be 5.0* V)
    P3 0 V (should be 5.0* V)

RF-Board
Q2 D 0.02 V (should be 0 V)
Q17 D 1.5 V (should be 2-3 V)
Q18 G 0 V (should be -1.0 V)
    S 1.45 V (should be 2-3 V)
    D 7.6 V (should be 6.3 V)
Q21 E 1.35 V (should be 1.6 V)
    B 2.1 V (should be 2.3 V)
    C 11.9 V (should be 13.2 V)
U4 P2 0 V (should be 2.4 V)
U5 P1 5 V (should be 0 V)
   P2 0 V (should be 5 V)

According to some old postings I tested the 8R line (J13 pin1). It doesn't
go 0 V when TUNE is on. Same post pointed to U10A ALC-control and those
pins seem to be wrong. Also PA0V pointed me to this direction.

I already received advice from Elecraft's Gary and send this info to him
too.

73 de Jukka, OH4MFA




_______________________________________________________________________
Parhaat hakupalvelut yhdessä osoitteessa: http://www.eniro.fi/

Suomalaisten yritysten tuotteet ja palvelut: http://yritykset.eniro.fi/



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