Re: LF: WSPR Reports - G3XBM, G3ZJO, G4KPX...(2)

[g3zjo <g3zjo@psk31.plus.com>]

Dave

Yes put it back to favor Rogers tests for sure.

I find that tuning my inverted L for 474KHz band makes my 40m OCF Doublet into a good 474KHz RX antenna, although tuning / loading the Doublet makes a useless TX antenna (the ends drop). The other combinations of all antennas influencing each other is no doubt endless.

Eddie

On 18/02/2014 13:46, Dave G3WCB. wrote:

Eddie, Roger,

 

Throwing good scientific practice out of the window, I changed two things at once (well, almost)!  Eddie's transmissions, up to and including the 11-46 utc spot, were received using the loop in 60 -240 deg orientation, but with the main Tee antenna connected to the TX. I now realize that coupling from this main antenna is affecting the directionality of the loop, and also it's apparent sensitivity.

 

Eddie's 12-06 utc transmission was received with the loop in the "favourable" 165- 345 deg direction, but with the TX antenna still connected. You can see that the signal is about 9 dB weaker. At this point the penny dropped and I realized what was going on. All WSPR spots after 12-14 UTC are being received with the loop in the 165-345 deg orientation, and the main antenna disconnected.

 

Eddie's transmissions now seem to exhibit a lot more signal strength variability, and I haven't received any spots from Roger since 12-00 today. So it looks like all my "improvements" have made reception worse....doh!

 

I think that the best course of action would be to put things back to the pre-12-00 utc configuration while Roger makes his improvements. Suggestions, anyone?

 

73 Dave G3WCB IO91RM 

-----Original Message-----
From: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org]On Behalf Of g3zjo
Sent: 18 February 2014 13:15
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: WSPR Reports - G3XBM, G3ZJO, G4KPX...

Dave
That will be an interesting test. I have a couple of similar loops and they just do not work here due to induced noise from the mains, I have tried ground level and bottom of the garden test to no avail. As I get away from one source of noise I start to approach another.
I also have a small 'window sill' loop which I took mobile / portable and it performs really well, away from home.

Roger
I will put an RX on and run the Grabber to check if I see you. May I suggest that you TX at other than the 6 an 8 minute slots. I TX at 06 etc. and also ruin a little of 08 etc. slots.

73 Eddie


On 18/02/2014 12:51, Roger Lapthorn wrote:

Thanks Dave,

Your reports have been very useful to me. Going to try an auto-transformer to see if I can match the earth-electrode "loop" any better later. Added a series inductor yesterday (about 200uH?) which increased antenna current about 20%

73s
Roger G3XBM

On 18 February 2014 12:23, Dave G3WCB. <ganymede444@btopenworld.com> wrote:

Chaps,

I'm aware that you've been using my WSPR reports to gauge the effectiveness
of your various QRP WSPR transmissions. I'm using a 80cm square tuned loop
at ground level with a fet pre-amp, feeding my trusty ICOM IC-PCR1000. I've
tried to keep the RX set up unchanged, but the loop is inclined to
"weathercock" around a bit, especially with the storms recently.

Also, my WSPR RX doesn't run 24x7, as I use the PC for other duties.

I went out this morning, and found that the loop is aligned along an axis
running 60 - 240 deg, which means that stations in the IO92 direction are
pretty much in the null direction. As an experiment, from 1214 UTC today I
have aligned the loop antenna in a 165 - 345 deg direction. To remove any
interaction with the main station "Tee" antenna, which is in the same
general area, I have disconnected this and moved my WSPR TX on to the short
vertical antenna, which is 30m away from the loop.

I'll swap the loop back to it's 60 - 240 deg orientation later on - I'll
announce when I've done this.

73, Dave G3WCB IO91RM