K2 #4520 up and running...

[HB9DUT]

Hi,

yes, K2 #4520 is up und running :-)
After i have changed the two transistors Q9 & Q10 the internal frequency
counter has no problem anymore.
It is really a pleasure to work with the K2.

But i have one small problem. On 17m and 15m my K2 has only very low output.
All other Bands are ok. Receiving is ok, only the output is low.

All measurements are done with an Wavetek SI 4031 Stabilock and should
be ok.
Voltage is 13.8V

Frequency      Offset        Pout       Current
  3.75 Mhz     10 Hz       14.9W    3.18 A
  7.10 MHz      7 Hz       14.9W    3.18 A
10.10 MHz      8 Hz       13.3W    3.08 A
14.10 MHz    13 Hz       14.0W    2.80 A
18.10 MHz      2 Hz       0.29W    0.75 A
21.10 MHz    10 Hz       0.32W    0.72 A
24.90 MHz    20 Hz       13.9 W   2.80 A
28.20 MHz    11 Hz       10.6 W   2.61 A            

I think the problem is not T1 or T2 because the output power on 12m and
10m are ok.
Maybe i have a problem with L10 & L11 or C32 & C32?

73 de Peter - HB9DUT


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[Jim Younce]

Peter:

I would look in the area of the Low Pass Filter section or the Bandpass
filter section.  A quick check of the low pass can be done on RX by
connecting the antenna to the rf out jack and then moving it to W1.  If the
signal level increases then the problem is in the Low Pass Filter section.

A good test of the Bandpass filter is to look at the RF voltage on the base
of Q5 in the tune mode on a good band and then on a bad band and see if the
level is way down as compared to a good operating band.  Check solder
connections on K5 and K6 and K11.  All other sections of the radio are
functioning if it works on other bands,   Also make sure that C33 is
installed in the correct holes.  If  I were a betting man I would bet on the
Low Pass Filter circuit that is common to those two bands.. (L23, L24,
C218-222)

Good Luck

73

Jim Younce K4ZM


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