March 10th / 11th Activity weekend

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g0mjw
Posts: 455
Joined: Sat Sep 20, 2014 9:15 am

Re: March 10th / 11th Activity weekend

Post by g0mjw » Sun Mar 11, 2018 10:04 am

g8gtz wrote:
Sat Mar 10, 2018 8:49 am

Tomorrow (Sunday) I am thinking to to go to Ridgeway above Didcot (IO91IN) which is good to the North and East - possible to work Steve at DD on 5.6 and also G0MJW and G4FRE on 24Ghz????
Got the 24GHz out. Made a small modification to enable hard PTT as well as volts up the coax. Should be ready to go.

Mike

g8gtz
Posts: 875
Joined: Wed Apr 07, 2010 6:26 pm

Re: March 10th / 11th Activity weekend

Post by g8gtz » Wed Mar 14, 2018 7:53 pm

As previously reported by Dave, on Saturday I went out to IO90LX and worked G8GKQ on 5.6 and 24GHz over a 90Km path. P5 pictures were exchanged on 5.6GHz and a 2 way DATV QSO on 24GHz with Dave running an HD web cam on his Portsdown to give superb pictures at 2Ms.



Sunday report to follow in a separate post

Noel - G8GTZ

(BTW - no idea why the picture is attached twice!)
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Last edited by g8gtz on Wed Mar 14, 2018 7:54 pm, edited 1 time in total.

g8gtz
Posts: 875
Joined: Wed Apr 07, 2010 6:26 pm

Re: March 10th / 11th Activity weekend

Post by g8gtz » Wed Mar 14, 2018 7:58 pm

On Sunday I went to Ridgeway above Didcot and worked Steve M0SKM on 146 - I also tried to work Arthur on 146 and 5.6GHz but failed on both bands :-(

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Mike G0MJW then came up to site and we tested his 24GHz gear which had not been turned on for 10 years and had a DATV QSO over a 3 metre path!

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But we did notice some very strange constellations on 24GHz - these were not there on the 146MHz IF signal but reproducible on the 24GHz link :-)

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73
Noel - G8GTZ

g0mjw
Posts: 455
Joined: Sat Sep 20, 2014 9:15 am

Re: March 10th / 11th Activity weekend

Post by g0mjw » Wed Mar 14, 2018 8:25 pm

Our 16 APSK signals were also only present at 2MS/s. They disappeared at other rates. Very strange, as this was completely repeatable. Maybe the proximity had something to do with it. It wasn't IF leakage as I was only putting the Portsdowns 10mW into my transverter and signals disappeared when the transverter was off. My PI camera has stopped working again and my C920 is on loan, so only testcards sent.

Mike

G4GUO
Posts: 511
Joined: Tue Feb 16, 2010 12:51 pm

Re: March 10th / 11th Activity weekend

Post by G4GUO » Wed Mar 14, 2018 11:15 pm

I saw something very similar to that (quad points in each quadrant) when I was doing some Pluto testing with Minitioune.
It turned out to be due to restricted transmit bandwidth, when I opened the Pluto's analogue filters up the problem disappeared.
Maybe the BW of your 24 GHz transvertor is not as wide as you think.

- Charles

g0mjw
Posts: 455
Joined: Sat Sep 20, 2014 9:15 am

Re: March 10th / 11th Activity weekend

Post by g0mjw » Thu Mar 15, 2018 7:32 am

Hi Charles,

We thought about this too - its not likely to be my transverter but the 2m IF at the receive end. Noel was using his 2m system which has narrow filtering to keep out all the pagers etc.

Mike

g8gtz
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Joined: Wed Apr 07, 2010 6:26 pm

Re: March 10th / 11th Activity weekend

Post by g8gtz » Thu Mar 15, 2018 9:11 am

As Mike says, we think that was the problem as I was using my standard 146.5 MHz rx system which has a multipole Pye Europa filter at 146 followed by an interdigital at L band so is very tight and we were running 2Ms on 24GHz - all previous 24GHz tests had been done using a Serit tuner at 145 with no filtering.

Noel

G4EWJ
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Joined: Wed Feb 17, 2010 10:11 am

Re: March 10th / 11th Activity weekend

Post by G4EWJ » Thu Mar 15, 2018 12:12 pm

I've had some strange constellations working across the desk. Some sort of multipath perhaps.

Brian
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