Jeremy,
70 ohms is too low on the +12 volt power line, you should see a large
capacitor charging and the resistance should climb if all is normal.
1 volt on the base during a TUNE is too high, so plan to replace Q11 and
Q13 - they are included in the K2PAKIT.
Yes, static can be induced by wind, rain and snow as well as nearby
lightning - we sometimes have lightning even in Winter.
Unfortunately, you will have to find where the problem origin is. You
can lift one end of R45 to remove Q5. Check again at the collector pad
for Q7 or Q8 after removing Q5.
Then to remove Q6, lift one end of RFC4 and check again.
To remove the RF Preamp from the 12 volt rail, lift one end of R74.
Check again.
To remove the Post Mixer Amp, lift one end of R82 and check once more.
To remove the TX Buffer, lift one end of R97 and check again.
If the 12 volt rail still shows low resistance to ground, you probably
have a faulty capacitor. Those are difficult to locate - it is probably
an electrolytic, so look for any that are not flat on the top. They
normally expand inside when they fail, so you are looking for a slightly
rounded top. Removal of all the capacitors on the 12 volt rail is the
next step if you cannot spot a bad one visually. Look at the schematic
and look for every line marked "+12v" - if there is a capacitor
connected to that line, remove it and check the resistance on the board
after each one.
Yes, a low resistance to ground is a nasty problem to troubleshoot and
just takes time to isolate to the failure. Work methodically - if you
jump around and try to "shotgun" it, the normal result is frustration.
73,
Don W3FPR
On 2/12/2014 8:58 AM, JeremyJones wrote:
With Q7/Q8 removed, the resistance from the Collector solder pad to ground on
both is 70 ohms.
Doing a "Tune" with Q7/Q8 removed results in 1.0V on the Base pads and a Low
P on the display. I do have the KAT2 installed, just in case this makes a
difference. This was done into a dummy load.
The antenna that I normally run is an 80m Carolina Windom strung up between
a tree in my front yard to a tree in my backyard. I have no additional
grounding to it, just the baluns that are part of the normal antenna design.
I am very cautious of lightning in the summer, and leave the antennas
disconnected when not using the radio, however given that its winter here
and sub zero temperatures, I didn't worry about it. I had never heard of
static caused by the wind. What is a good way to protect against this?
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