Jim,
I sacrificed one of the little jumpers with the black thin coax. I probably should not cut more. I was going to order more from China but have not yet.
Scope is HP 54522A 500 MHz. Purchased on eBay.
Bob ________________________________ From: Jim McCullers via pacsat-dev pacsat-dev@amsat.org Sent: Wednesday, March 6, 2024 9:00 AM To: Bob Stricklin bstrick@n5brg.com; 'Pacsat Dev' pacsat-dev@amsat.org Subject: [pacsat-dev] Re: Blinky Transmiter
Thanks for the box. At the moment it’s hanging.
The smallest coax I have is RG-174. I do have a few connectors with the same you use on the board to SMA and can sacrifice one except the coax is the transparent stiff variety, not certain of the number.
If your is more flexible and you can space an few inches send some with the box. Otherwise I can make something work. Need to raid the scrap cable bin.
What scope do you have? Now wish I had bought a 200mhz but settled for 100 and 4-channels analog. Digital scope is also 100mhz.
Hope to finish my RF probe tonight and test.
Jim
Jim, Thanks for your report.
I did reconnect the transformer to the 4X splinters using the fine coax and things seem to be working fine that way. I have not tried it with packet data yet but will do that when I can.
The image below is the dif input to one of the receivers. The south trace is offset by 1 cm so we can it it better. Phasing looks good. Noise is due to poor ground in my setup mostly I feel.
I received my 3D printer and I have printed three more of the plastic boxes for the programming board. I will mail you and Chris one maybe tomorrow.
Bob
[cid:image001.png@01DA6FA4.B5237350]
On Mar 5, 2024, at 4:02 PM, Jim McCullers via pacsat-dev <pacsat-dev@amsat.orgmailto:pacsat-dev@amsat.org> wrote:
I did some analysis on Blinky’s transmitter last night and did not see the spurs Bob saw on his board.
My experience with using a spectrum analyzer close in looking for spurs or phase noise is limited so more analysis is needed.
I did look at the harmonics and the second was down 48 db from the fundamental (+15 to -33 dbm).
The third harmonic was in the noise and undetectable.
Now, for receiver board surgery.
Jim McCullers
WA4CWI
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