Electronics > RF, Microwave, Ham Radio

Yaesu FRG-7000 Communications Receiver Restoration

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xrunner:
I got this unit from a ham friend who got it at a ham fest. he asked if I wanted it, I could just pay him the same that he gave for it. After I got it home I gave it a quick check-out, and it seemed to be in fair condition. Dirty and needing an alignment. But after looking at stock photos of this radio I noticed something was not right. Someone in the past had replaced three of the original knobs with the wrong ones. I don't know if the originals got broken or some kid did it because they thought it looked cool. After I saw that I had just put it away to see if any knobs would become available on Ebay.

So far no knobs for this radio have shown up, and from what I see Yaesu didn't use these knobs on any other radio. So I decided to try and create the original knobs and 3D print them. You can see what the originals look like in the second photo of a stock radio. The knobs that were replaced had set screws, but I don't think that will be necessary to have. Two of the knobs are on a "D" shaft and do not need a set screw. The other one, which is a volume control, I'm not sure about. You can see at the end the shaft has a slot cut. Is that an insertion point for a nib in the end of the original knob? I don't know yet about that, I'll cross that bridge when I come to it.

First I'm going to design the other knob which shouldn't be too hard, and is duplicated twice, one for the band and one for the mode. The diameter is easy to get from the indented hole in the radio, but the other dimensions will have to be approximated from the picture. The knobs are black and I already have that color PLA. I can paint the white line on easily.

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German_EE:
Nice, not seen one of those for a few decades. Do they use a Wadley Loop for tuning or is it a synthesizer?

PA0PBZ:

--- Quote from: German_EE on December 28, 2019, 10:20:45 am ---Nice, not seen one of those for a few decades. Do they use a Wadley Loop for tuning or is it a synthesizer?

--- End quote ---

It has a separate MHz knob, that's a typical indication that it is a Wadley.

xrunner:

--- Quote from: German_EE on December 28, 2019, 10:20:45 am ---Nice, not seen one of those for a few decades. Do they use a Wadley Loop for tuning or is it a synthesizer?

--- End quote ---

Indeed as PA0PBZ stated is uses the Wadley Loop System. It has the basic modes - AM, USB, LSB, & CW. AM filter is 6 kHz and the SSB filter is 3 kHz. It is a standard fair receiver but has good reviews on eHam.

I made a lot of progress on the first knob design which is for both the band and mode. I got the basic design down and had to play with the shaft hole diameter but I got a great fit now. Today I need to add the fill-in for the D-part of the shaft so it will fit even better (and print in black  :P ).

After the knobs are done I will proceed to a full cleaning and alignment, I do have a service manual.

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xrunner:
Finished the new knobs. I went ahead and designed-in set screws too. Painted on a white strip, looks acceptable. Better than the bastardized knobs somebody slapped on it.

But, some bad news. I was playing with an alignment on the RF unit and two of the ceramic trimmers broke. The insulating disc that has one of the plates just cracked the first time I tried to turn them - probably never been touched since the factory. There is one trimmer and one coil for the input for each band. That's how these things go with 40-50 year old electronics. So now I must source replacements.

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