Re: Update on my progress - Now General RF Issue

[KD8NNU]

Well I finally had time to work on the shack to fix my RF problem.

First thing was to get a dummy load that could run full power of the
amp.  This is done and guess what I had some problems with using the
dummy load.

After much research I determined that my ground was not correct.  What I
mean by not correct it was not a single point and the wires were
insufficient.  I now have 10ga single strand wire for my single point
ground with crimped and soldered ends.   After the grounding things were
fine from 40m on up.

Next all the short coax between all devices was replaced and the PTT to
the amp and on off switch lines were coiled and a #31 snap on ferrite
was used for each one.

Now I did a retest and now I can use the amp all the way down to 80m
with no issues with the dummy load.   I get the same results with the
antenna.  I did some QSO's on 75 and no issues at all.

I still have a bit of a hickup with 160m but research of the amp and the
date of the amp indicates that there is an update needed (resistors
changed) to fix this problem on this band.  So most likely the amp will
be moving to the Jeep in the future and I don't have a 160m antenna I
may not worry about figuring out the update.  I will call SGC just to be
sure I know what it will take.

What have I learned.

With low power 100W a lot of poor installation techniques work and you
have no idea that you have a problem  With an amp things have to be
correct to work.  I had lots of poor techniques.

Proper grounding is important, if you don't use a single point ground
you can expect to have ground loops.  There are many references on the
Internet that show grounding schemes that will create ground loops, so a
single point ground is important.   You also have to have sufficient
copper on the ground as small diameter wire does not cut it.    I do not
know if braid would have been better than the 10ga but I did not have
braid at this time.

Proper choking of all leads that connect to each device in the shack.
In now have a minimum of 7 turns of cable for each device with a #31
choke clamped on to each one.

When you bury cable you must make sure that you purchase cable that is
rated for direct bury if you don't you have problems.  Cable rated for
direct bury is marked on the coax, my first cable was not rated this
way.

What is left to do.

I do not have a proper choke at the antenna so I need to make one in the
next couple of weeks.   I have a bunch of clamp on ferrites but it is
not sufficient for 160m, which will be required if I try to run the amp
assuming I make the update.  I do it for the sake of the K3 cause I can
run barefoot.

Next weekend if I have time I will again connect the loop antenna and
try that again.   However, this time I suspect that I will have a better
chance to make it work based on what I now know and what I have done to
the shack.

Bottom line this is why its called amature radio.

Thanks for all the help and information that folks sent to me, as I am
now on the air again and safer.


~73
Don
KD8NNU
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