Re: LF: TX > RX isolation test

[N1BUG <paul@n1bug.com>]

Hi Roelof,

Thanks for the test and interesting information!

Since many years I have special interest in "extreme" or very
challenging amateur radio QSOs. I have been a 160m DXer, 6m DXer, 2m
and 70cm EME (when it was all CW) and so on. LF is the next
challenge. In some ways it is like no other.

On 160m we have a saying: "You can never have too many receive
antennas." I think this is at least true for LF also. Eventually I
want to have a few RX antennas: omnidirectional, K9AY (or some
substitute), loop. But I have to make them one at a time. At the
moment, I have a three stage plan. Stage one, build a K9AY or EWE
facing northeast. Stage two, replace the 'low noise vertical' with
an e-probe or modify the existing antenna to make it work more
properly. Stage three, build a loop.

The hard part of the K9AY is making a 15m pole to support it.

73,
Paul N1BUG




On 07/18/2018 08:54 AM, Roelof Bakker wrote:
> Hello Paul,
> 
> For your information, today I have tested a ´low noise vertical´.
> This is a 50 mm diameter and 3.30 meter long aluminium pole.
> The capacitance is 47 pf.
> 
> Using a transformer of 80 turns primary and 8 turns secondary on a high mu 
> toroid the output 
> as measured with a PERSEUS SDR on the carrier of a local NDB on 399.5 kHz  is 
> -97 dBm. The 
> output on my standard mini-whip mounted 4 meter high is -81 dBm. The output 
> is low, but not 
> completely useless, depending on the amount of local noise it picks up. At my 
> location the 
> signal to noise ratio is 10 dB worse as on my mini-whip antenna.
> 
> The K9AY is an excellent antenna and if you have the space, I should go for 
> it.
> 
> I do prefer an omnidirectional antenna as at LF you never know the exact path 
> of arrival.
> I am not only interested in receiving amateur radio signals but also hunt 
> NDB's, NAVTEX and 
> DGPS stations. NDB's and DGPS stations from Canada are received here every 
> day, Summer 
> included.
> 
> 73,
> Roelof, pa0rdt