Mark,
In the base K2, the things in common for 17 and 15 meters are the
bandpass filter and the low pass filter.
With your RF probe, you can find out quickly which one is giving you
problems.
Remove the KPA100 if you have that installed and use the BNC ANT
connector from the base K2.
Set the K2 at 5 watts and connect a dummy load.
Connect the RF Probe ground wire to one of the ground loops on the RF board.
Set to 15 meters and do a TUNE while measuring the RF Voltage at the
cathode of D7.
Then switch to 20 meters and make the same measurement - this is just a
'sanity check'.
Is the RF voltage as great or greater on 15 meters compared to that on
20 meters?
If so, the transmit circuits prior to the bandpass filter are working OK.
Remember the 15 meter RF voltage measured at the cathode of D7.
Then measure the RF voltage at jumper W6 (if the K60XV is installed,
measure at K60XV Pi pin 3 or pin 5).
Is the RF Voltage almost as great as it was at D7 cathode? If so, the
bandpass filter is working fine, check for the problem in the Low Pass
Filter. But if the RF voltage is considerably lower, check the bandpass
filter.
73,
Don W3FPR
On 11/4/2010 7:50 PM, Mark Adams wrote:
> Hi Gang,
>
> During my last contest foray, I noticed that making Qs on 15M was difficult.
> Turns out that with only about 50mW, it is! And 17M is likewise low. The
> rest of the radio is FB. Also, the current draw on 15/17 is basically the
> same in RX and XMIT.(My Astron's meter moves about one needle width.) The
> Power Control has no effect on the 15/17 power levels.
>
> I am hoping that there is some "common" problem that I can easily fix. Can
> anyone point me in the right direction? I have an RF probe so I can trace
> the signal to look for loss. Would be nice to start close to the expected
> problem area.
>
> 73,
> Mark K2QO
> FN03ra
>
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