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Ebay Lucky-Dip FRG7

 

Good day All.
My Ebay lucky-dip FRG7 has arrived, and its what I hoped it would be, see pics below.
There are a few things that Im struggling to identify, so if anyone has any input, that would be great, thank you.
?
The serial number has extra digits, so if anyone recognises the number, please shout up.
Serial number: 17 8M 240615
?
The PCB marked DL6 SW 004 is power from the DC rail, it 'seems' to have an SO239 on one side and a BNC on the other side, no connection into the unit itself at all. SO239 SW2 is no longer connected to SW1 or BC. Does anyone know what this is please.
The XTAL is 38.66667Mhz
?
There is something that looks like an additional modulator marked astec, does anyone have any info on this please.
?
At the moment, its powered up, white noise when AM is selected, the lock LED will go out above 15Mhz ish but wont go out below.
Putting a TinySA outputting at 25Mhz with 100Khz AM-mod near the antenna plugs induces the signal at 25Mhz and is auditable.
?
That's about as far as I've got so far.
?
Br John.

20250207_111134415_iOS.jpg
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20250207_113824507_iOS.jpg
20250207_113834949_iOS.jpg
20250207_113858010_iOS.jpg
20250207_113924758_iOS.jpg
20250207_122654286_iOS.jpg
20250207_111150996_iOS.jpg
20250207_111219072_iOS.jpg
20250207_111234523_iOS.jpg
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20250207_111251875_iOS.jpg
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20250207_111349568_iOS.jpg

 

Hi John,
What is a "lucky-dip"?
?
73 Roger VE7LB
 

Sold as seen not working, spares or repairs
?
 

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The extra unit sounds like a converter to allow reception of another band of frequencies. As in converting say the 2m band down to 28MHz or similar. And the replacement 455KHz filter-nice!

Sent from Mike's iPhone

On 7 Feb 2025, at 19:32, reeferjon via groups.io <reeferjon@...> wrote:

?
Good day All.
My Ebay lucky-dip FRG7 has arrived, and its what I hoped it would be, see pics below.
There are a few things that Im struggling to identify, so if anyone has any input, that would be great, thank you.
?
The serial number has extra digits, so if anyone recognises the number, please shout up.
Serial number: 17 8M 240615
?
The PCB marked DL6 SW 004 is power from the DC rail, it 'seems' to have an SO239 on one side and a BNC on the other side, no connection into the unit itself at all. SO239 SW2 is no longer connected to SW1 or BC. Does anyone know what this is please.
The XTAL is 38.66667Mhz
?
There is something that looks like an additional modulator marked astec, does anyone have any info on this please.
?
At the moment, its powered up, white noise when AM is selected, the lock LED will go out above 15Mhz ish but wont go out below.
Putting a TinySA outputting at 25Mhz with 100Khz AM-mod near the antenna plugs induces the signal at 25Mhz and is auditable.
?
That's about as far as I've got so far.
?
Br John.
<20250207_111134415_iOS.jpg>
<20250207_111141341_iOS.jpg>
<20250207_113818883_iOS.jpg>
<20250207_113824507_iOS.jpg>
<20250207_113834949_iOS.jpg>
<20250207_113858010_iOS.jpg>
<20250207_113924758_iOS.jpg>
<20250207_122654286_iOS.jpg>
<20250207_111150996_iOS.jpg>
<20250207_111219072_iOS.jpg>
<20250207_111234523_iOS.jpg>
<20250207_111242302_iOS.jpg>
<20250207_111251875_iOS.jpg>
<20250207_111258468_iOS.jpg>
<20250207_111301496_iOS.jpg>
<20250207_111349568_iOS.jpg>
 

The unit with the 38.667 MHz x-tal is a FET 2 meter converter.
Is was publiced in UKW Berichte.
Here you can find some information? about it:

Br Marcel


Op vr 7 feb. 2025 21:42 schreef Mike Anthony via <g4thn=[email protected]>:

The extra unit sounds like a converter to allow reception of another band of frequencies. As in converting say the 2m band down to 28MHz or similar. And the replacement 455KHz filter-nice!

Sent from Mike's iPhone

On 7 Feb 2025, at 19:32, reeferjon via <reeferjon=[email protected]> wrote:

?
Good day All.
My Ebay lucky-dip FRG7 has arrived, and its what I hoped it would be, see pics below.
There are a few things that Im struggling to identify, so if anyone has any input, that would be great, thank you.
?
The serial number has extra digits, so if anyone recognises the number, please shout up.
Serial number: 17 8M 240615
?
The PCB marked DL6 SW 004 is power from the DC rail, it 'seems' to have an SO239 on one side and a BNC on the other side, no connection into the unit itself at all. SO239 SW2 is no longer connected to SW1 or BC. Does anyone know what this is please.
The XTAL is 38.66667Mhz
?
There is something that looks like an additional modulator marked astec, does anyone have any info on this please.
?
At the moment, its powered up, white noise when AM is selected, the lock LED will go out above 15Mhz ish but wont go out below.
Putting a TinySA outputting at 25Mhz with 100Khz AM-mod near the antenna plugs induces the signal at 25Mhz and is auditable.
?
That's about as far as I've got so far.
?
Br John.
<20250207_111134415_iOS.jpg>
<20250207_111141341_iOS.jpg>
<20250207_113818883_iOS.jpg>
<20250207_113824507_iOS.jpg>
<20250207_113834949_iOS.jpg>
<20250207_113858010_iOS.jpg>
<20250207_113924758_iOS.jpg>
<20250207_122654286_iOS.jpg>
<20250207_111150996_iOS.jpg>
<20250207_111219072_iOS.jpg>
<20250207_111234523_iOS.jpg>
<20250207_111242302_iOS.jpg>
<20250207_111251875_iOS.jpg>
<20250207_111258468_iOS.jpg>
<20250207_111301496_iOS.jpg>
<20250207_111349568_iOS.jpg>
 

thank you Marcel, a great starting point, I will pull the images down today
br
john
 

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I saw another box which is not standard under the chassis alongside the Crystal oscillator. Perhaps another converter?

Sent from Mike's iPhone

On 8 Feb 2025, at 08:38, reeferjon via groups.io <reeferjon@...> wrote:

?
thank you Marcel, a great starting point, I will pull the images down today
br
john
 

Marked Astec, not sure what that is yet.
 

Today spent a few hours to see why its deaf and the lock led stays on below approx 15Mhz.
These are the measurements I got so far.
Anyone any thoughts?
?
Inject 3Mhz into antenna
Mhz set to 3Mhz, preselect set to 3Mhz
Band set to B
Am set to AM
ATT and tine set to normal
Dial set to 0Khz
S meter reads 9-11
Lock LED is lit, will not go out (goes out above 15Mhz)
TP101 = 58Mhz approx 350mV pk-pk
TP103 = 0hz ?approx 0mV pkpk
TP104 = 2.5Mhz approx 100mV pkpk
TP106 = 1Mhz approx 800mV pkpk
TP107 = 0Mhz approx 0mV
TP109 = 0Mhz approx 0mV
TP110 = 52Mhz
(TP104 with Mhz and band set to 28Mhz = 52Mhz 200mV pkpk)
 

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See comments below line by line. I have to ask first though, do you have circuit diagram? Better still the September and October 1981 articles in Short Wave magazine by JL Linsley Hood? With these to hand and read and understood you will be in a much better place to get the Frog working again.

?

From: [email protected] <[email protected]> On Behalf Of reeferjon via groups.io
Sent: 08 February 2025 18:52
To: [email protected]
Subject: Re: [Yaesu-FRG-7] Ebay Lucky-Dip FRG7

?

Today spent a few hours to see why its deaf and the lock led stays on below approx 15Mhz.

These are the measurements I got so far.

Anyone any thoughts?

?

Inject 3Mhz into antenna
Mhz set to 3Mhz, preselect set to 3Mhz
Band set to B
Am set to AM
ATT and tone set to normal
Dial set to 0Khz
S meter reads 9-11

?

Lock LED is lit, will not go out (goes out above 15Mhz). The LED is driven by the Darlington pair Q110 and Q111. When there is enough voltage (>0.5rms) present at TP110 then this is enough to extinguish the LED. Therefore, you are not getting enough signal down the Q107 to Q109 amplifier chain. Q111 will be on and the LED lit with its base drive supplied by R131. But when Q110 gets enough base drive to turn on, it will remove the base voltage from Q111 and the LED will go out.

?

?

TP101 = 58Mhz approx 350mV pk-pk This shows that the Q201 oscillator stage is functioning correctly.

?

TP103 = 0hz ?approx 0mV pkpk Here is certainly one problem. If you are injecting a 3MHz signal into the antenna socket then you should be able to see this at TP103. So the signal is getting lost somewhere between the antenna socket and TP103. Check at the input to T102 and then at C101 which is the input to RF amp Q101. After this there is the LPF which is that rod with several coils.

?

TP104 = 2.5Mhz approx 100mV pkpk This is at the output of the second mixer Q105. For a signal to appear here this is likely coming from the signal you see at TP101 which gets fed two ways, one of which ends at the first mixer which is Q102 and Q103. Try looking for this at VR101. After this the signal will progress through T105 T106, Q104, T107 and T108 then Q105 before appearing at TP105.


TP106 = 1Mhz approx 800mV pkpk This is the output signal from the sealed box under the chassis from the crystal oscillator Q301. So this is working

?

TP107 = 0Mhz approx 0mV This suggests that Q106 which is the IC on the board, has died. This chip mixes the 58MHz and 2-3MHz signals and so if this is dead, there will be no signal at TP107 ( and neither will there be enough signal at TP110 to turn off the LED)

?

TP109 = 0Mhz approx 0mV This reinforces my guess that Q106 is dead since this test point is on the end of the chain starting at Q106. You should be seeing the output of the Q106, Q107, Q108 and Q109 chain here.


TP110 = 52Mhz
(TP104 with Mhz and band set to 28Mhz = 52Mhz 200mV pkpk)

I am puzzled about this result. If there is no signal at TP109 then there will be none at TP110 either.

?

As to there being no sound output try touching or injecting say 3KHz at the centre connection of the AF gain control. That at least will prove the AF PA stage and associated components.
 
Edited

Thank you Mike.
I do have the afore mentioned pages and they are great IF the set is working :-)
?
I did some more investigation around Q106, all of the supplies measure correct.
No o/p on pin3 which is TP107
No i/p on Pin11
?
TP101 confirms as 58Mhz
Then we come to a PD made up of R117 and R118, I'm not getting anything 'measurable' after R117, what level would that lightly be.
I calc that if i/p is 350mV then o/p should be around 112mV.
?
I know the tracks are a bit fragile on these so will await a response before unsoldering on end and checking the values of R117 and R118.

Screenshot 2025-02-09 143051.jpg

 

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Indeed, I get 112mV as well at the junction of R117 & R118. ?So something is shorted to ground here. R118 perhaps?
Sent from Mike's iPad

On 9 Feb 2025, at 15:10, reeferjon via groups.io <reeferjon@...> wrote:

?

[Edited Message Follows]

Thank you Mike.
I do have the afore mentioned pages and they are great IF the set is working :-)
?
I did some more investigation around Q106, all of the supplies measure correct.
No o/p on pin3 which is TP107
No i/p on Pin11
?
TP101 confirms as 58Mhz
Then we come to a PD made up of R117 and R118, I'm not getting anything 'measurable' after R117, what level would that lightly be.
I calc that if i/p is 350mV then o/p should be around 112mV.
?
I know the tracks are a bit fragile on these so will await a response before unsoldering on end and checking the values of R117 and R118.
<Screenshot 2025-02-09 143051.jpg>
 

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Hey Mike.
Changed it today, nothing wrong with it, took the opportunity to resolder the joints around the area, no difference.
Will retake measurements of all TP again tomorrow and may crank up the signal gen a few db
Br
John


On 9 Feb 2025, at 21:35, Mike Anthony via groups.io <g4thn@...> wrote:

? Indeed, I get 112mV as well at the junction of R117 & R118. ?So something is shorted to ground here. R118 perhaps?
Sent from Mike's iPad

On 9 Feb 2025, at 15:10, reeferjon via groups.io <reeferjon@...> wrote:

?

[Edited Message Follows]

Thank you Mike.
I do have the afore mentioned pages and they are great IF the set is working :-)
?
I did some more investigation around Q106, all of the supplies measure correct.
No o/p on pin3 which is TP107
No i/p on Pin11
?
TP101 confirms as 58Mhz
Then we come to a PD made up of R117 and R118, I'm not getting anything 'measurable' after R117, what level would that lightly be.
I calc that if i/p is 350mV then o/p should be around 112mV.
?
I know the tracks are a bit fragile on these so will await a response before unsoldering on end and checking the values of R117 and R118.
<Screenshot 2025-02-09 143051.jpg>
 
Edited

Started again from the beginning.
1. stripped out the 2m converter, completely rewired the antenna connections and removed a pair of 1meg resisters from So239.
2. stripped the Band switch and cleaned the wipers, this made a big difference
3. cleaned the Dx/LOCAL switch again
4. mechanically aligned the preselect/Mhz and Khz dials
5. cleaned up potential dry joints
6. washed off the PCBs with IPA and inspected tracks
?
Results, much better but still issues.
Worked part way through the alignment, stopped due to scope not being up to parr.
Worked through Q101 to Q111 voltage chart, found Q110 and Q111 C&B voltages out to list, adjusted VR102 nearly 1/4 turn and they are now somewhere near, LED goes out on most of range now, but its clear there is still a problem in the selective filter area.

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