|
Hi Ken
The alpha peak in the screen shot is fairly
typical but they vary according to propagation by about +/-50%. The
stations are easily identiified by the alternating pulses, as I guess they are
really a navigation chain. I also get a permanent signal about
9.9kHz but don't know its origin.
The miniwhip feeds a Lowe HF-225 receiver, and if I
tune to BBC R4 on 198kHz, the S meter reads S9+50db, it is probabl;y more but
held at that point by the RX agc. My location is similar to yours,
as I have a block of flats nearby, and we are on low lying ground.
The photo shows the miniwhip without the extension on the antenna, which is now
fitted for VLF and is of similar length to yours. You will
notice that the miniwhip is supported by a collection of poles, the two highest
being wooden broomsticks, keeping metalwork well clear, otherwise too much
noise is picked up. The main TX aerial wire slopes down away from
the miniwhip with a metre or so of lanyard tied to the lowest metal pole (about
8ft from the ground. Overall, the miniwhip is about 20ft
high. I think that your chokes should
be ok.
I hope this information is useful, 73 Dennis
M0JXM
----- Original Message -----
Sent: Tuesday, March 08, 2011 7:32
PM
Subject: LF: Re: Re: Alpha Stations
Hi Dennis.
Thanks for the reply, the small peak at
about 12.6 on your screen shot is that typial?. I was not sure what I
should be looking for on Winrad, or even if Stefan's preamp was
working when I saw a similar peak at 9.941, 13.30 UTC. The preamp was at
about 3m high, I have modified the circuit for power feeding, by winding a
130mH choke on a FT50-77 ferrite, this has been holding up the project as I
made four of them, two for the PA0RDT miniwhip which is next. The preamp is at
the end of the garden about 2m from the 8m main 2inch aly mast, unfortunately
the new 6th Form college is 60m from the mast.How would you suggest I
evaluate the preamp performance, I tried sliding a four turn by 60mm loop over
the 350mm whip and feeding it fron the station osc but that did not seem to do
anything. Your thoughts please.
73
Ken
M0KHW
----- Original Message -----
Sent: Tuesday, March 08, 2011 5:41
PM
Subject: LF: Re: Alpha Stations
Hi Ken
See attached Winlab screen shot of a group of
alpha stations, shown as little white dashes on the upper
window. They start just below 12 kHz. Spectrum lab shows
more clearly where they are located, but the real time shot on Winrad
gives a better idea. I suffer from interference from the 25kv
East Coast Main LIne railway just a 100 yards or so from my aerial at
Biggleswade. The antenna is a PA0RDT miniwhip, see also
top right of the picture where it is mounted on a
pole.
73 Dennis M0JXM
----- Original Message -----
Sent: Tuesday, March 08, 2011 2:09
PM
Subject: LF: Alpha Stations
Hello All.
Were there any Alpha Stations transmitting on
9.941 at 13.30 UTC?, I was checking to see I my Stefan 2 - 24 kHz preamp
was working using Winrad and saw a small peak 9.941 about 15dB above
the noise, disconnected the amp and definately coming down the antenna.
Not sure how large a signals I should see from Stefan's pre amp when
switched on the noise level does not change any suggestions
please.
73s Ken
M0KHW
IO91TV
|
