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Thanks,

I was thinking only of the kHz dial replacement. The DD-103 is way above what I want to spend for this project, I was thinking of around $25.

Hi Mike,
Quite a few digital readouts will work on the FRG-7. The problem is in getting an accurate readout down to 100 Hz.

Info on several counters can be found in the Files section folders 5 & 6.

An offset counter counting the VFO frequency will be at the mercy of the H. GEN. accuracy. If the HG 1 MHz crystal is off by 100 Hz the H.GEN output will be off by 300 Hz on the lowest band and 3,200 Hz on the highest band. This inaccuracy will carry through using most offset frequency counters.

The ESP DD-103 can hold corrected offsets for 32 bands so it could be set to be accurate on an FRG-7.

I would check your H.GEN for accuracy before buying a display. If it is dead on any of the counters in Folder 6 would work well.

My plan is to see if the HG crystal can be modified to use a trimmer to net it to 1 MHz. If it can't I intend to replace the crystal with a TCXO module that can be netted to 1 MHz. The TCXO may not work properly with the Harmonic Generator (HG) circuit as is.

73
Roger VE7LB

Interested in adding digital readout to the FRG-7
has anyone done this in the past few years?
what product did you get ?
I see possibilities on the net but I don't want to end up waiting weeks to get something that is a PIA to program

thanks

Hi Roger, Lex,

I think the operation is much simpler. The pick-off point in the H.GEN will have a comb of frequencies and the FRU-7 has no way of determining which one is selected in the receiver; that depends on the setting of the MHz dial (55.5-84.5 MHz 1st oscillator). Also, from the photos the display electronics looks like some pretty simple CMOS - probably presettable counters plus decode and display chips. There doesn't appear to be a crystal on the display board either. What this points to is using the H.GEN as the timebase for the FRU-7, with probably a simple LPF to suppress everything above 1 MHz.

The only way to determine what the MHz reading should be is to measure the 1st oscillator and calculate as follows; MHz(set)? = [freq (1st osc) - 55.5] MHz. Round to nearest MHz as the Wadley loop takes care of any fractional MHz ( over +/- 100 KHz say).

I have been thinking of a "full" digital display for the FRG-7 for a while. So far? I have a 'Blue Pill' board (STM32F103C8 micro) driving a 6-digit led board (TM1637- based) working. Total cost is under AUS $10. A bit of programming and a few transistors should take care of the KHz part of the display (the micro has some neat counters but the insane complexity of configuring them has me on a steep learning curve). Then a few more transistors and a HCMOS decade counter (to divide the 1st oscillator down to something the micro can handle) should take care of the MHz side of things. Will report back when I have the whole working.

Hi Lex,

Thanks for adding to the information about the FRU-7 display. I have previously contacted you off list about buying the unit.

I gave to much credit to the 70's technology in my first post. The MHz digits could be derived by subtracting 3 from the H.GEN MHz signal.

Looking at the Block Diagram on page 8 of the FRG-7 manual. The FRU-7 must be counting the 3 - 32 MHz output of the H.GEN and subtracting the VFO frequency. Then the counter circuit must have a preset of .455 MHz that adds to the sum above. For example when tuned to 10 MHz:

H.GEN output is 13 MHz and the VFO is 3.455 MHz (13 - 3.455 = 9.545). Then add the IF frequency of .455 MHz to the above and you have 10 MHz. The FRU-7 doesn't display the MHz digits and shows .000 on the LED's.

It should be a more accurate display, on the upper bands, because the 1 MHz crystal doesn't have a calibration trimmer and any inaccuracy will show up as you increase the receive frequency. For example if the 1 MHz is off by 100 Hz the H.GEN output would be off by 300 Hz on the lowest band and 3,200 Hz on the highest band. Because the FRU-7 counts the H.GEN and VFO frequencies and the VFO can correct for the H.GEN offset the FRU-7 should show .000 when tuned to WWV.

73
Roger VE7LB

Hello Roger,

I used to have one in a FRG-7 which I got from a OM (the FRG-7 belonged to his father (SK OM Joop PA0JPC) and was in a bad shape). The counter worked, but I didn't like the look of it (and the jumping last digit made me nervous HI). So when I got my hands on a donor FRG-7 (which was in even worse shape), I removed the counter and restored the original drum.?

Last week the OM wrote to me that he was sorting through his fathers stuff and found all the original documentations including the (unused) warranty card and bill dated 19 may 1978, and he send it to me for my collection.?
Yesterday I received it and finally got installation documentation (Unfortunately no schematic) from the 3 digit the counter (it only slows the 0-999 KHz).?

Now having the name I googled around and found a ad in a magazine ( ) 1978. Indicating it's from B.Brookes Electronics from Norwich UK.
?

Scrolling through the video's on my mobile phone and I found 2 video's I made when I started the restoration of this FRG-7. So I uploaded them to YouTube the public can see them.

?&??

When I removed the Brooks FDU7 counter I documented how it was installed in the FRG-7. When you look a the photo's you can clearly see that it's digital technology from the 70's (reminding me of the components my father used for his electronics experiments in the 70's).?

I believe the aluminum case isn't original (it looks hand made).

For those who are interested, I don't use it and have it on sale on my website :??(?price is negotiable HI )

73 and stay safe

Lex PH2LB?

Hi Lex,
Thanks for uploading the Brooks FDU-7 display install instructions. Looking at the instructions I see that it uses two coaxes to count the MHz frequency and the VFO frequency for a 5 or 6 digit readout (EG : 10.000 or 10.0000?).? I have never heard of the Brooks unit and there is nothing on Google. Were they sold in Europe? If you happen to have one in your FRG-7 I would appreciate a picture.

73
Roger VE7LB

Lex PH2LB <lex@...> added folder /Brooks FDU-7 - logic counting device

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The following files have been uploaded to the Files area of the [email protected] group.

• /Brooks FDU-7 - logic counting device/Brooks FDU-7 - logic counting device for FRG-7.pdf

By: Lex PH2LB <lex@...>

Description:
Scan of the Brooks FDU-7 logic counting device for FRG-7 installation document.

At the moment I don't have spare switch which i can take apart to design the knob.?

When I get my hands on one, I can try to design a switch knob. Or if somebody can give me detailed drawings etc.?

--

73 Lex PH2LB?

Can you do me a power switch??

Hi Steve,
Thanks for your work on the FRG-7 schematics. I numbered your new folder 4 - FRG-7 service notes so it will appear near the top of the default Files screen. I converted the two gif schematics to pdfs while leaving your original gifs alone.

73
Roger VE7LB Group Owner

Hi All,

I've uploaded a some files to /g/Yaesu-FRG-7/files/FRG-7%20service%20notes/schematics
Here's a bit from the covering document. Feedback welcome. Enjoy!

"There appear to be a proliferation of FRG-7 schematics on the web, of varying quality and with many differences.
The aim of this document is to present two high-resolution schematics which capture as much as possible of these
differences, plus a guide to tabulating differences of any schematic and the two given here.
These two schematics are presented here as files FRG-7_schematic_v{1/2}.0.gif."

The following files have been updated in the Files area of the [email protected] group.

• //FRG-7 service notes/schematics/FRG Schematic Notes v1.0.pdf

By: Steve Quigg (VK2TUM) <stevequigg@...>

Description:
Notes about 2 hi-res schematics, also uploaded in this directory

The following files have been uploaded to the Files area of the [email protected] group.

• /FRG-7 Switch Notes v1.0.pdf

By: Steve Quigg (VK2TUM) <stevequigg@...>

Description:
Notes on POWER/LIGHT switches and toggles for FRG-7

Thank you for linking to my blog.?

You have also a lot of interesting posts on you blog. Will take this evening catch up on them.?
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73 Lex PH2LB?

Printed one today and it looks good :?

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73 Lex PH2LB?

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73 Lex PH2LB?

Hello Gerald,

?

There is indeed a stop system on the main dial. Mine also had problems and only needed some cleaning. Checkout my FRG-7 mod page on my website.

?<< image showing mechanism.?

Good luck.?
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73 Lex PH2LB?