[Elecraft] Antenna Problems with K3 firmware 5.57

[Bill Frantz]

On 4/1/17 at 6:44 AM, elecraft at mailman.qth.net (Dick Bacon via 
Elecraft) wrote:

>... that was to check and tighten the three screws on the bottom cover
>for the LPA transistors (p63 in assembly manual).

I got the same advice, but mine were quite tight. If you have 
problems with erratic SWR or Power readings, check those screws 
before sending an email to support. :-)

An update on the broadcast station interference problem aka the 
antenna problem.

I looked at KLIV's data in the FCC database (thanks Jim K9YC for 
the links). It turns out that after sundown, KLIV changes the 
pattern of its antennas to put most of the power directly toward 
my QTH. 
<https://transition.fcc.gov/Bureaus/MB/Databases/AM_DA_patterns/429300-67110.pdf>. 
No wonder I have a problem.

Jack, W6FB wondered how long a coax stub for 1590 KHz would be. 
A quick back of the envelope calculation came up with a bit more 
than 100 feet. I pulled out a piece of RG-58 labeled 104' and 
hooked it up as a stub. The problem get a lot better, but it had 
a noticeable effect on the bottom end of the 160M band. The stub 
is far from being a notch filter.

Adding another piece of coax got it below the 160M band, but I 
worry about suppression of odd harmonics at higher frequencies. 
I think I have used the antenna for QSOs on every amateur band 
from 160M to 6M inclusive. So on to something that took longer 
than 10 minutes to try.

I dug through the junk box and found a 560 pF 1KV cap and a 
T68-2 core. Quality time with the ARRL Handbook said to use 56 
turns on the core, which I did with some #30 wire. So far, knock 
on wood, this seems to get proper power output on the entire 
160M band. And the core only gets warm if you hold the key down 
for a long time. I'll need thicker wire before the next 160M 
RTTY contest.

73 Bill AE6JV

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