29MHz trans Atlantic DX...

[radiogareth]

No reception seen at the Milford PA SDR for 1/2 and hour so dropping carrier....3:15 Local.
Gareth

[G3VZV]

I saw a video signal on 29.150 MHz briefly around 1540UTC on the K3FEF KiwiSDR I could also just hear myself using FM voice soon afterwards.100 watts to OCF dipole..
exciting times...
73 Graham G3VZV
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[K0ZAK]

Watching the signals this morning in a rainy Baltimore day. Lower than they had been, but Gareth's signal all of a sudden came way up and data locked immediately, just prior to him shutting it off.

11-25-2022 Test with G4XAT.jpg (374.16 KiB) Viewed 5556 times

[radiogareth]

Thanks John, made my day that
Gareth

[g0mjw]

Congratulations - I was at work but maybe tomorrow?

[radiogareth]

Thanks Mike, partly down to your excellent transverter which has clocked up 10's of hours of TX so far.
Finished the MRF300 '27MHz application note' amp today and fired it up. It does go rather well although I found the bias was poorly tracking as it all warmed up. Simple circuit needs some thought, but an easy 200W at about 50V & 5.5 amps.
Using the same 18ks script, Justin and I tried 146.5MHz on my co-linear and about 1 watt. Easy copy.....
Tried 50.7Mhz tried too, and my Pluto obliged with a carrier which locked locally. That's going to be fun next E's season.....
Pics show the amp, heatsink is OK at around 100W but needs more airflow to sustain 200W. The fans out of the 70cms NEC TV amp look suitable.....
I may not be around tomorrow afternoon (best propagation was between 1:30 and 2:30 today) so hope you have success too.
Gareth
The heatsink was machined fully flat to completely match the supplied MRF Dev kit aluminium block.

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MRF300_Fan_ex_CPU.jpg (89.21 KiB) Viewed 5515 times

Heatsink_29MHz.jpg (124.15 KiB) Viewed 5515 times

[g0mjw]

Thanks Gareth,

Interesting you didn't need to modify that choke - incidentally I got 300W once I did the Mod. Probably 200W beforehand. The shoulders get worse above 100W, but I am using 48V. I did notice it got better at higher voltages. Also noted the drift in the bias. We need to fix that as it is quite bad, it doubles.

Mike

[radiogareth]

I did mod the choke Mike, the "33" one has the top coil turn bent up at about 40 degrees. I didn't drive it any harder as only had a dvbs source at the time.
Also wasn't sure the heatsink was enough.....
Onward...
Gareth

[g0mjw]

I was just looking for some data on the MRF300 Start kit some of us are using for 29MHz and I see Mouser claim to have 100 in stock part number 771-MRF300AN-START

Mike

[radiogareth]

Mouser also have stock of the equally handy (but less RF) MRF101 https://www.mouser.co.uk/ProductDetail/ ... 6CUQ%3D%3D
Gareth