K4

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K4

Ralph S
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
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Re: K4

K8TE
Ralph,

You answered your own question although part of your description doesn't
logically make sense.  If the chain link fence is the source of the mixing,
how can your FT-1000 out-perform your K3?  If the mixing occurs in the fence
(very possible at a dissimilar junction), then that junction generates an
unwanted signal in the bands you use.  Only disconnecting the antenna from
the transceiver will solve that problem.  The filter protects the
transceiver's front end and has no impact on the fence's mixing capability.

I used to work for the company that operates our local (770-KKOB) 50 KW
electron emitter.  It is line-of-sight from our home.  I use a high pass
filter in between the antenna and K3 to reduce its impact on 160m.  The
"standard" MFJ antenna analyzer won't work properly with that much RF in the
neighborhood.

Living in New Mexico, rust is not a big problem for chain link fences or
cars/trucks.  However, the 50 KW transmitter is a huge problem for many
devices, especially telephones, in the neighborhood.  We used to provide a
lot of phone line ferrite filters before cell phones became so abundant.

It's difficult to solve problems without understanding their causes.  Good
luck!  73, Bill, K8TE



--
Sent from: http://elecraft.365791.n2.nabble.com/
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Re: K4

Vic Rosenthal
In reply to this post by Ralph S
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
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