Technical Topics > The RF Workbench
Stretchyman 40 W TX Reliability Modifications
Charlie_Dont_Surf:
It's been a few months since I visited this forum or posted here. I've had other things going on (e.g., keeping my employment). You might remember I wrote up the issues on Stretchy's 40 Watt TX here:https://www.hfunderground.com/board/index.php/topic,67747.msg230885.html#msg230885
Some of you wrote me to tell me that you had exactly same problem. Some of you asked for more detail. I finally got back to looking at what needed to be done to modify for reliability in August and this is the result. For the two of you that wanted to see this, here it is. :D
Link: https://app.box.com/v/h5a3lyzgep45pzz49
EDIT: Fixed the title. It will be great once I learn to spell correctly.
ChrisSmolinski:
Thanks for sharing. As an engineer I find design reviews/improvements very interesting to read. You often learn something you can later use yourself.
Stretchyman:
I have developed a drop in PCB and most have already received one, for any that haven't please PM me.
It delays the 24V until the 12V and oscillator is fully up.
Str.
ChrisSmolinski:
I wonder if there's any mods that can be done to reduce FMing, such as improving (or adding, as I suspect there is none) the stability of the voltage regulation on the oscillator? (Not sure which wattage version this is)
Charlie_Dont_Surf:
I don't have the schematic for his frequency synthesizer so I can't help you.
The only thing I can say is that he now has what may be a zener diode on the switched 12 V input to the synthesizer/FET driver. (Or maybe it is a TVS device.) A zener might help.
I will note that later versions appear to to be more stable; I noted no FM'ing on the units I tested.
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