[Elecraft] K4 Question

[Fred Jensen]

During the BPL conflagration a number of years ago, most of the concern 
seemed to be interference "to" amateur radio operations.  I became a bit 
concerned that my neighbor would go BPL and my 1200 HF watts would kill 
his I'net.  Technically and legally his problem, not mine of course, but 
I still needed to get along with him.

We had a 69 KV line running through our property tying two hydroelectric 
plants together, with a primary 12 KV distribution line underneath which 
would have been the BPL feed.  At closest approach my antenna and the 
lines were about 165 m apart.  I modeled them and my sloping-V in EZNEC 
and found that the coupling between them was -32 to -35 dB on all bands 
except 80 and 160, where it ran about -17 dB on both bands.  On 80 and 
160, the power lines were in my near-field.

So, I would conclude that Wayne's 30 dB, based on a different model, is 
a pretty good estimate.  Fortunately, BPL faded into the sunset and I 
was never confronted with the problem.

73,
Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 6/24/2020 12:12 PM, Greg Troxel wrote:
> Wayne Burdick <n6kr at elecraft.com> writes:
>
>> I set mutual attenuation to 30 dB, a rough estimate of the path loss
>> using dipoles 500' apart at 7 MHz. This is a pretty wild guess,
>> though. Loss could be much higher if the antennas were oriented to
>> avoid coupling, and it'll vary with frequency, terrain, actual
>> distance, etc. Of course path loss could be lower with gain antennas
>> at either or both ends, aimed at the other. (A situation generally
>> avoided at FD.)
> I think 30 dB loss is an extremely conservative test and that very few
> people will see coupling that strong.
>
> At my club's 2019 Field Day, with help from several, I made measurements
> of received signal strength at several of our stations with various
> antennas, with a nominal 100W test carrier.  Measurements are just
> reading a P3 -- and note that none of the P3 owners had paid for the
> NIST-traceable calibration certificate.
>
> Setup was CW station with K3newsyn, digital station with IC7300, only
> 20m separation from one CW antenna to the digital antenna.  And SSB
> station with K3newsyn, 200m away.
>
> We did not have trouble, but always had at least 50 kHz separation.
>
> Received levels ranged from S9+40 to S9+73, with S9+50 typical.
>
> So received signals were
>
>    -33 dBm min, -23 dBm typical, 0dBm max
>
> With +50 dBm transmit, that works out to path loss:
>     83 dB max, 73 dB typical, 50 dB min
>
> (The 0 dBm received signal was between an OCFD and a G5RV, about 20m apart.)
>
> It is interesting to hear of S9+65 from a neighbor.  Even if they are
> running 1.5 kW, seems like it must be only a few hundred meters
> separation.  If it's farther the details of distance, tx power, antenna
> types would be interesting.
>
> I realize this is not responsive to Eric's question about the K4, but
> thought that additional real-world cosite path loss data points would be
> of interest..
>
> 73 de n1dam
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