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Messages - M R I

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The RF Workbench / Re: speech synth + Kahn ssb tx on arduino
« on: December 29, 2021, 1645 UTC »
I have been working with Arduino in my transmitters and receivers. Nice work. Keep us informed on your progress.

Equipment / Re: R-390a Users
« on: December 25, 2021, 0504 UTC »
Hello MRI, I would be very interested in the mod to make the R-390a go below the broadcast band. I have done only the AGC diode mod which works very well. Can you enlighten me on what that LF mod might be?


Hello Radioroom. All that is needed is a in a .01 disc capacitor connected to test point E209 going to your antenna with one end to ground. For best results use or make a bifilar antenna isolation transformer for ground loop hum and common mode rejection. The 390A will go down to 20Kc. Disconnect this antenna input when using higher bands.

Equipment / Re: R-390a Users
« on: December 19, 2021, 1924 UTC »
 I have a R390 Collins made that has original paint and meters. I have done very little repair work on it. I also have a R390A that I have restored it adding original meters to it. If you want to experience newer performance on both add a SDR interface to the 455Khz IF or add a tap on input BNC connectors before the filters for a wider spectrum display. Run your SDR software. The only thing is to keep in mind you will have some frequency drift over time which I minimized by adding a stable filament voltage regulator to the PTO VFO. I prefer the R390 performance over the 390A cost reduction version (except the mechanical filters) and by using the SDR you get the advantage of the brick wall filters anyway. One big advantage is you can use the 390 /A in a high RF field as long as it is not in your passband because of the excellent front end selectivity.

 For very good stability I may add a VFO stabilizing circuit to the PTO or switchable in out DDS VFO. This is just a possible future update but not necessary for most listening conditions.

 By the way you can add a simple mod that will allow the R390 to go below the broadcast band.

QSLs Received / Re: Burry Coockie Hour eQSL 28 Nov 2021
« on: December 12, 2021, 1745 UTC »
Thank you AC for another cool QSL.

North American Shortwave Pirate / Re: X-FM 4185 AM 0101 UTC 4 DEC 2021
« on: December 05, 2021, 0115 UTC »
Good signal. Testing on my modified Sony ICF-2010 for stereo AM since it already has a Stereo IC sync detector decoder chip inside.

S 9 +10 with Long Cool Woman (In a Black Dress) Remix ?

Peaking S9+10

Hello Two Dog Radio.

Nice music with Take Five by Dave Brubeck

0232 Open The Door by Blues Cousins

0239 BLP Brian Lucas Project - Setting Sun

Equipment / Re: Radio Plus Quantum Phaser Schematics
« on: November 13, 2021, 0243 UTC »
I looked around and did not find anything. You can replace the the pre amp FET or transistors around the affected burnt resistor as a starting point. I repaired my MFJ-1026 for a similar problem. Then modified it so it did not suffer from the same fate. It has been working for a few years now.

I will have the QSLís out soon.  8)

QSLs Received / Re: Illuminati eQSL 29.Oct 2021
« on: November 07, 2021, 0320 UTC »
Thank you AC for the very cool but hot QSL ;)

I would have liked to have posted my QSL here but it might get me in trouble. Lol

Hello Alex send your report and recording to      Mix.Radio.International@protonmail.com

 I will be working up a QSL for this show as I receive more reports from Europe.

 Thanks for listening in.

North American Shortwave Pirate / Re: X-FM 4185 AM 0002 UTC 1 NOV 2021
« on: November 01, 2021, 0217 UTC »
Finishing the stereo mod to my hardware sync detector off the 455 IF on the Collins R-390. I have very good stereo now at 16k bandwidth. Thanks for coming back on the air again Redhat

I modified my home made synchronous AM sideband selectable detector for stereo. Now in Stereo DSB mode. I have a great signal with a solid PLL lock on the Collins R-390. Thanks for the great vinyl show of music.

Mine has various modifications. It needed diodes installed so the pre amp FET does not blow with a external Ant. This was not the FET I replaced for this problem. As far your marginal performance It had a production run beyond expectations that sold very well. Still a good performer for a portable.

I have a Sony ICF-2010 that had low receive. I replaced two FETís with cross reference replacements. They worked. The gain was not as good as the originals. I replaced them with originals from Sony. It went back to normal.

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