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Author Topic: Videos on the Yaesu FRG-7 - Wadley conversion architecture, and how-to tune  (Read 2421 times)
W2AEW
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« on: October 31, 2016, 08:36:38 AM »

Here are a pair of videos that I put together on the Yaesu FRG-7 receiver.  The first is a video describing the interesting Wadley drift cancelling conversion scheme used in this rig (often called a Wadley Loop, even though there is no feedback loop involved).

https://www.youtube.com/watch?v=JvS9tBWAc1s

The second video simply shows how to tune/use a receiver that uses the Wadley conversion architecture:

https://www.youtube.com/watch?v=8fhnt8wdo-w

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N4UE
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« Reply #1 on: October 31, 2016, 06:09:16 PM »

Alan, thanks for the videos. You have a pristine example there. I have one of the later models that has the fine tuning control located above the volume pot. I have done a few mods to mine which replace the aging electrolytic caps and added a Kiwa IF filter. I also did the mod to the fine tuning control, which stock was too fast for SSB.
Not to boast, but I was also able to find the Sears version. It's pretty neat, being all black and having a "Sears" logo instead of the Yaesu one.

Even though I have dozens upon dozens of receivers, I was always amazed at the FRG-7's simple, low parts count design, that worked so darn well. I first read about the Frog in the book:
Communications Receivers Past and Present" by Osterman. Love the latest volume of the book as well.
The Frog received 5 stars, as it deserves. Just like my 3 Drake R-4Bs. ha ha

Thank you again. LOVE your videos. Taught this 70 year old a bunch.

ron
N4UE
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W2AEW
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« Reply #2 on: October 31, 2016, 07:57:51 PM »

Alan, thanks for the videos. You have a pristine example there. I have one of the later models that has the fine tuning control located above the volume pot. I have done a few mods to mine which replace the aging electrolytic caps and added a Kiwa IF filter. I also did the mod to the fine tuning control, which stock was too fast for SSB.
Not to boast, but I was also able to find the Sears version. It's pretty neat, being all black and having a "Sears" logo instead of the Yaesu one.

Even though I have dozens upon dozens of receivers, I was always amazed at the FRG-7's simple, low parts count design, that worked so darn well. I first read about the Frog in the book:
Communications Receivers Past and Present" by Osterman. Love the latest volume of the book as well.
The Frog received 5 stars, as it deserves. Just like my 3 Drake R-4Bs. ha ha

Thank you again. LOVE your videos. Taught this 70 year old a bunch.

ron
N4UE

Thanks for the great comments Ron.  I'd appreciate any info/links you have on the mods you've done to yours. I picked up one of the Sears versions at a hamfest a few weeks ago. It is is nice shape also, and works great.
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http://www.youtube.com/w2aew
N4UE
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« Reply #3 on: November 01, 2016, 10:06:05 AM »

Hi Alan. I put in the Kiwa filter for increased selectivity. It's switchable from the rear via a small toggle switch. I also added a small cap in series with the fine tuning cap. I tried several until I found the value that 'felt' right. I also replaced all the paper caps with new, 105C rated ones. None of the originals were very far out of their ESR spec, but it was just for PM.

I kept the Frog next to my main operating table and would use it every now and then. I then replaced it with a succession of other great receivers like the R8A, Collins 75S-3, etc.

Check out my review of the FRG-7 here. The fine details elude me! I believe some of the mods were from 'ModsDK'......

ron
N4UE
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W2AEW
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« Reply #4 on: November 01, 2016, 11:37:24 AM »

Hi Alan. I put in the Kiwa filter for increased selectivity. It's switchable from the rear via a small toggle switch. I also added a small cap in series with the fine tuning cap. I tried several until I found the value that 'felt' right. I also replaced all the paper caps with new, 105C rated ones. None of the originals were very far out of their ESR spec, but it was just for PM.

I kept the Frog next to my main operating table and would use it every now and then. I then replaced it with a succession of other great receivers like the R8A, Collins 75S-3, etc.

Check out my review of the FRG-7 here. The fine details elude me! I believe some of the mods were from 'ModsDK'......

ron
N4UE

I looked at the schematic to see where the fine adjust was connected, and I see that simply adding a small series cap will "slow down" the tuning rate.  I'll play with that at some point.

I noticed that the AGC on my Sears rig is noticeably slower than on the FRG-7 I had in the video.  I wonder if they changed it on the later production units (or on the Sears units) compared to the early production frog.
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http://www.youtube.com/w2aew
RENTON481
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« Reply #5 on: November 04, 2016, 02:51:19 AM »

I only did two mini-mods to mine, changing the value of a capacitor in the ANL circuit, which helped reduce noise a little bit. And there was a resistor (if memory serves) that I removed from the antenna circuit on Band B or Band A (can't remember). It's a resistor that's there that doesn't really need to be there. Sharpened the tuning a little on that band.

Both 'mods' are fairly well known in FRG-7 circles.

Being that there is no diode protection on the FRG-7, it's a good idea to clip a couple back to back diodes in between your antenna input and the ground. It's easy to do if you just use a high-Z wire -- no soldering required.
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N8YX
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Posts: 456




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« Reply #6 on: November 09, 2016, 08:32:33 AM »

I had a Frog in the 2005-2006 time frame. Good little radio. I sold it along with my other Yaesu gear of the period.

Fast forward to this year:

A nice FR-101S, FL-101 and matching accessories managed to make their way into my station. As did another FRG-7. I didn't mod my first one but the second iteration is going to get a lot of changes.

First and foremost is the swap of the IF/AF Board with one from an FRG-7000. Next, addition of more IF filters and the modification of the "Tone" switch to allow selection of them independent of the Mode switch. The AF Gain control gets a concentric knob and control set (from an FT-101) and it'll incorporate a Tone control in place of the switchable feature.

AGC timing will be tied to the Mode Switch. A medium rate for AM, slow for SSB and fast for CW but I doubt I'll use the rig on that mode very much. The Lock LED gets a dual-color unit (red for unlock; green for lock). I wish there was enough front panel room for a concentric IF (or RF) Gain/Squelch control, though I think I can live without it. Maybe convert the Fine Tuning control to a varactor-based design and stuff another concentric pot in its place.

I'm also going to make a replacement front panel with new control nomenclature.

Just a few refinements to make the rig a bit more usable, but otherwise a decent set. I enjoy mine. It's powered up 24x7, monitoring various Ute and SWBC goings-on.
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