I am line-of-sight to a 50kW AM transmitter (at least one, maybe more
co-located at the site). I was using a vertical antenna, which was very
good at picking up AM BC signals.
I had a problem that the plentiful RF overrode the bias on my K3's T/R
switch diodes, causing IMD all over the lower bands. I made a HP filter
that cut off at about 2 MHz (I don't operate on 160m) and that cleaned
it up.
When I switched to a horizontal antenna, the problem went away. Now in
addition, I am using a Johnson Matchbox, which is very good at
attenuating out-of-band signals.
If you have a similar problem and you make a HP filter, note that it has
to have power-handling capability so you can transmit through it. The
t/r switch and the K3 (and probably in the K4) is before the alternate
RX input/output, so you can't just put the filter in the receive path.
As someone else pointed out, none of this applies if the IM is being
generated by chain-link fences or any other non-linear junctions out there.
73,
Victor, 4X6GP
Rehovot, Israel
Formerly K2VCO
CWops no. 5
http://www.qsl.net/k2vco/
On 19/04/2020 22:31, RALPH TURK wrote:
Wayne et all
My only concern before I order a K4 is how it will work with two high power
AM transmitters near me.
10KW day,1kw night KVOI south of me and a 50kw day only KUAT AM north of me.
At some time, I will need to borrow or rent a k4 for a week and see how it
behaves
The majority of my operation is between 2-3.5 Mhz, 4 to 7mhz, 7.3-10mhz, 11mhz
to14mhz.
I also use my radio on most ham bands. I currently use a K3 with all bells and
1000MP
The MP seems to handle the intermod better then the k3
The intermod is not caused within the radios but cause by rusty chainlink
fence, poor power line
grounds etc. My antennas are not the problem. I tried a sharp cutoff filter
for everything below
3.5mhz. No positive measurable results.
Ralph, W7HSG, AFA9RT
520-444-6610
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [email protected]
