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Author Topic: Radio Plus Quantum Phaser Schematics  (Read 592 times)

Offline skeezix

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Radio Plus Quantum Phaser Schematics
« on: November 13, 2021, 0152 UTC »
Does anyone have the schematics for the Quantum Phaser? I have one and it was working well until I decided to tune my doublet and didn't change the antenna switch before putting 5W into the Phaser.

There was a resistor that was burned, so I replaced that (which I think was the correct value, but unsure since it was burned on the third stripe), the 2N3866 transistor, and the J310 JFET. However the signals are still far below what they should be. No other visible damage.

I bought this a while back and don't remember if I had instructions and/or schematics, and if I did get that, no idea where I put it for safe keeping.
Minneapolis, MN

Offline M R I

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Re: Radio Plus Quantum Phaser Schematics
« Reply #1 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.
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Offline skeezix

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Re: Radio Plus Quantum Phaser Schematics
« Reply #2 on: November 13, 2021, 0254 UTC »
Just now I did fix it. As I was tracing the circuit, I discovered two poorly soldered connections that I failed to do correctly when replacing the first resistor and the transistor. Corrected those and now it works great again.  At least now I have a small stock of replacement resistors, transistors, and JFETs for if (when?) I do that again.

However, still wouldn't mind the schematic for future use.

« Last Edit: November 13, 2021, 0311 UTC by skeezix »
Minneapolis, MN

Offline RobRich

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Re: Radio Plus Quantum Phaser Schematics
« Reply #3 on: November 13, 2021, 1602 UTC »
Considered adding a basic RF limiting protection circuit? You could build one for like $2 to $3. Lots of designs online using cross diodes plus maybe a cap, resistors, and/or choke. Either build it in the phaser, or place it on a board backwards between apparently your antenna switch and phaser so it can be easily serviced or just outright replaced.
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Offline skeezix

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Re: Radio Plus Quantum Phaser Schematics
« Reply #4 on: November 13, 2021, 2218 UTC »
I had started to consider adding that, but wanted to fix this first. Have another loop that's connected to a transceiver and it could also use that protection as well.

 
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