Yaesu FRG7 - UK Vintage Radio Repair and Restoration Discussion Forum

LyntonP · 17th Nov 2018, 3:33 pm

Hello everyone. Thanks for accepting me to the forum.
I was quite an active amateur a few decades ago. Still have some rigs up in the loft but not used for a long time.
I recently purchased a Yaesu FRG 7 communication receiver and have been listening using my G5RV aerial.
The radio was very dirty inside and out, so I gave a good cosmetic and electrical clean and have to say I am impressed with its performance.
However during the clean I discovered a modification that has me a little puzzled.
Mounted on the front panel is a latching switch which when pressed seems to desensitize the receiver.
Attached is a photo. Anyone have any idea what this is for?
On the photo there are four yellow wires. from the left 1,2,3+4. Under normal operation wires 2+3 are common. When the switch is latched 1+2 are common.
Any suggestions?
Thanks in advance

G8HQP Dave · 17th Nov 2018, 3:49 pm

It may be an input attenuator.

g8jzyian · 17th Nov 2018, 4:06 pm

Could it be a mechanical if filter?
Ian

http://charlietango.co.uk/yaesu-frg-...w-t18881.html?

Restoration73 · 17th Nov 2018, 4:38 pm

The board shown is the Toko mech filter unit to increase selectivity over the fitted 6 kHz ceramic filter. The two IF transformers on this board are for matching, but the increased
filter loss may cause apparent reduction in gain.

My preferred method was to switch in the Murata 2.7kHz ceramic filter CFJ455k although care had to be taken to maintain input and output isolation.

LyntonP · 17th Nov 2018, 4:54 pm

Thanks for the suggestions chaps.

I had done some digging on the internet and found the Charlie Tango listing, but my browser would't let me open the site. Ian your link allowed me to look and yes the item in my receiver is very similar. Unfortunately in my case it is mounted upside down so I cannot see any numbers.

Can't say I have gone looking for any SSB up to now, but I will give it a go tonight.

What I don't like is the fact that the 'on off ' switch is mounted on the front panel. Pity it cannot have been done a little more discreetly. More digging on the web says it is a Toko 455KHz SSB filter.

More questions to follow I'm sure

Thanks for the help. Spot on sir. I will give it a go tonight.

Cheers, Lynton.

LyntonP · 18th Nov 2018, 3:48 pm

I had a try at listening to some SSB last night but wasn't very successful. Either the bands were very quiet or my old G5RV needs a looking at.
Found one German gentleman on 80 DL160EMMA. A commemorative station of some kind, and a Russian gentleman RK3AW on 15. With the filter in circuit I had to crank the volume up to maximum to hear anything at all. yes it killed all the noise on 80 which was running at +10db but I could hear the signal better without the filter?
Also noticed that the further I tune upwards irrespective of which Mhz scale I was dialled into the radio goes deaf?
I think the whole set could do with a once over and maybe an alignment, but this is beyond my experience.
I do have a friend who was very good indeed with the inner workings of radios but he is in poor health now and unable to help. I wonder does anyone know someone in the North West who is experienced and reliable?
All my local radio shops have long since gone.
I compared results with my Trio R600 and managed to pull the SSB out despite the lack of bells and whistles, but the FRG7 beats it hands down in all other respects.
Thanks for the help
Lynton

dodgy-dxer · 19th Nov 2018, 8:50 am

https://kenwoodcommunications.co.uk/...lshpool-radio/

Under this umberella is Castle Electronics who do repairs and are very well regarded

Found the direct link http://www.hamradiosales.co.uk/CASTLE-1A.htm

73 Fred
G4BWP
Satisfied customer

Andrew2 · 19th Nov 2018, 9:43 am

I'm wondering if there is something a bit wrong with the installation of that filter. We can expect a small extra loss, but it shouldn't make the set so deaf. Properly installed a narrow SSB filter can transform the set from 'not very good at all for SSB' to really quite useable.

Nuvistor · 19th Nov 2018, 10:35 am

If there is any doubt about the filter, either installation or it being faulty, return the radio to standard configuration, repair any faults then sort out the filter.

It’s quite possible that a bad filter or install could degrade the radio when it is supposed to be switched out of circuit.

LyntonP · 19th Nov 2018, 11:46 am

Thanks again for the answers and links to reliable service centres. I agree that the filter may be causing a degradation to the performance and it does seem that it is not working correctly. My initial thoughts were to remove it completely. It does look as if part of the circuit board has been scratched away during its installation, presumably to put it in circuit? Since I bought the receiver to listen to broadcast stations and not SSB I think I will remove the device. I will do a little more digging to see if I can find some installation instructions for the filter which may help in returning the set back to original condition.
Again thanks for all the help.
Cheers
Lynton

LyntonP · 19th Nov 2018, 3:45 pm

Ok I took the plunge and removed the filter one wire at a time checking if the radio still functioned. Ended up having to put a small jumper wire on the circuit board that seemed to have been modified. What a difference! No longer deaf at the top of the dial, I can tune in SSB easily as the original filter seems to be working, and broadcast stations are bending the needle. Perhaps it doesn’t need an alignment after all? Photos show the jumper wire and the filter and switch after removal. Couldn’t find any fitting instructions on the web so no idea if it had been fitted incorrectly.
Thanks for all the help.
Might move on to my non functioning Hallicrafters next?

m0cemdave · 20th Nov 2018, 12:05 am

I'm not sure if this applies to yours, but a lot of mechanical filters use synthetic rubber foam to float the filter inside the casing.
After 30 or 40 years it perishes and either turns to either sticky goo or powder, and the filter then suffers from very high loss. So it wouldn't be surprising if your filter is faulty.

I appreciate that you won't want to do this, but for general interest: diehard restorers take them to bits, very carefully, and replace the foam - there are various articles on youtube and the internet describing the method.

Adding a narrow filter for SSB is a very common upgrade for FRG7's, and there is a way of doing it using the existing switches instead of drilling the front panel.

LyntonP · 20th Nov 2018, 2:06 am

Dave this sounds very interesting. I understand the advantages of a narrow filter and your comment about using the existing switches is intriguing. I will look further on the web but may come back to you on this one.
Lynton

Keith · 20th Nov 2018, 12:36 pm

Hi Lynton,
I fitted an addition crystal filter to my FRG7 which was switched in using the mode switch (can't remember the details). It did make a big improvement to SSB performance but I found that the drift on the rather crude BFO beacme a bit of a problem. Great receiver for AM broadcast bands though - pity there's not much on there now!

LyntonP · 20th Nov 2018, 1:29 pm

Keith Interesting comments, and I followed the link back to the article on the KW. Great pictures of the filter rebuild, but I think this would be beyond the capabilities of my eyesight and wobbly hands! I did undertake quite an extensive search on the Internet last night for more information regarding mods on the FRG7 but didn’t really find a great deal of information. One chap had come up with a two colour mod for the lock led, but nothing about fitting narrower filters. For the time being I will enjoy the radio as it is, but keep searching for for any further information.
Once again thanks for all the help
Lynton G4XCQ

JanWra1 · 21st Nov 2018, 5:48 pm

Hi Guys

In the early 70´s I had an early FRG7 before the RIT was added and was quite pleased with it, later added the RIT, but didn't do anything abt the filters. However in the late 70´s There were at least 2 modified versions of the Yaesu FRG 7 marketed by Gilfer in New Jersey and some other US company. The Gilfer mod included a couple of Murata filters and one could either buy the radio modified by Gilfer or buy the mod as a kit. For details check the link below.
The Gilfer FRG7 was featured in WRTVH some time in the late 70´s if my memory is correct.
www.scrid.com/document/218916488/FRG7-Mod-Gilfer
Hope this helps.

Jan
]

Bazz4CQJ · 21st Nov 2018, 6:16 pm

Quote:

The Gilfer FRG7 was featured in WRTVH some time in the late 70´s if my memory is correct.
www.scrid.com/document/218916488/FRG7-Mod-Gilfer
Hope this helps.

Jan, I cannot get that link to work; just seems to go to the scrid homepage; any ideas?

B

G6Tanuki · 21st Nov 2018, 6:20 pm

IMHO there's a typo: it's scribd not scrid ??

JanWra1 · 21st Nov 2018, 6:34 pm

Sorry made a typing error

It is : "scribd"
And if this doesn't work search for "FRG7 Mod Gilfer"

Jan

John KC0G · 22nd Nov 2018, 4:45 am

Quote:

Originally Posted by LyntonP

Keith Interesting comments, and I followed the link back to the article on the KW. Great pictures of the filter rebuild, but I think this would be beyond the capabilities of my eyesight and wobbly hands! I did undertake quite an extensive search on the Internet last night for more information regarding mods on the FRG7 but didn’t really find a great deal of information. One chap had come up with a two colour mod for the lock led, but nothing about fitting narrower filters. For the time being I will enjoy the radio as it is, but keep searching for for any further information.
Once again thanks for all the help
Lynton G4XCQ

Hello Lynton

There were several articles published in the late 1970's re. fitting additional filters to the FRG-7. See for example:
Radio Communication (RSGB) Aug 1978 and the follow-up in Dec 1979
Short Wave Magazine July 1978 and follow-up in Sept 1979, and also March 1979. There was a two-part article on other improvements to the FRG-7 in the Jan and Feb 1980 issues.
You can find the SWM articles at www.americanradiohistory.com

A number of the early filter mods used the TOKO MFL455 mechanical filter which was available from Ambit International in Brentwood. You can find the relevant data from their Techknowledgey No. 1 dated 1978 at:
http://www.milair.co.uk/mfl.pdf

I think that Ian Keyser, G3ROO published an article on turning the FRG-7 into a transceiver. I cannot find it right now. In the article he said that the Toko MFL455 was no longer available, but that a Kokusai filter was. That also came from Ambit (techknowledgey No. 4) In fact they also sold an upgrade kit using this filter.

IMHO, you are better off using a Murata ceramic filter as suggested by Restoration 73 in post #4.

I have just found more FRG-7 mods articles in Practical Wireless. See the Aug, Oct and Nov 1984, Feb 1985 and June 1986 issues. Again these are available at www.americanradiohistory.com

Back in the day (over 30 years ago) a number of companies supplied upgrade modules for the FRG-7.

HTH and 73

John KC0G

17th Nov 2018, 3:33 pm	#1
LyntonP Hexode Join Date: Nov 2018 Location: Greater Manchester Posts: 305	Yaesu FRG7 Hello everyone. Thanks for accepting me to the forum. I was quite an active amateur a few decades ago. Still have some rigs up in the loft but not used for a long time. I recently purchased a Yaesu FRG 7 communication receiver and have been listening using my G5RV aerial. The radio was very dirty inside and out, so I gave a good cosmetic and electrical clean and have to say I am impressed with its performance. However during the clean I discovered a modification that has me a little puzzled. Mounted on the front panel is a latching switch which when pressed seems to desensitize the receiver. Attached is a photo. Anyone have any idea what this is for? On the photo there are four yellow wires. from the left 1,2,3+4. Under normal operation wires 2+3 are common. When the switch is latched 1+2 are common. Any suggestions? Thanks in advance Attached Thumbnails

17th Nov 2018, 3:49 pm	#2
G8HQP Dave Rest in Peace Join Date: Sep 2008 Location: Solihull, West Midlands, UK. Posts: 4,872	Re: Yaesu FRG7 It may be an input attenuator.

17th Nov 2018, 4:06 pm	#3
g8jzyian Pentode Join Date: Jan 2009 Location: Liverpool, Merseyside, UK. Posts: 149	Re: Yaesu FRG7 Could it be a mechanical if filter? Ian http://charlietango.co.uk/yaesu-frg-...w-t18881.html? Last edited by g8jzyian; 17th Nov 2018 at 4:09 pm. Reason: added ref

18th Nov 2018, 3:48 pm	#6
LyntonP Hexode Join Date: Nov 2018 Location: Greater Manchester Posts: 305	Re: Yaesu FRG7 I had a try at listening to some SSB last night but wasn't very successful. Either the bands were very quiet or my old G5RV needs a looking at. Found one German gentleman on 80 DL160EMMA. A commemorative station of some kind, and a Russian gentleman RK3AW on 15. With the filter in circuit I had to crank the volume up to maximum to hear anything at all. yes it killed all the noise on 80 which was running at +10db but I could hear the signal better without the filter? Also noticed that the further I tune upwards irrespective of which Mhz scale I was dialled into the radio goes deaf? I think the whole set could do with a once over and maybe an alignment, but this is beyond my experience. I do have a friend who was very good indeed with the inner workings of radios but he is in poor health now and unable to help. I wonder does anyone know someone in the North West who is experienced and reliable? All my local radio shops have long since gone. I compared results with my Trio R600 and managed to pull the SSB out despite the lack of bells and whistles, but the FRG7 beats it hands down in all other respects. Thanks for the help Lynton

19th Nov 2018, 8:50 am	#7
dodgy-dxer Heptode Join Date: Mar 2008 Location: Newmarket, Suffolk, UK. Posts: 612	Re: Yaesu FRG7 https://kenwoodcommunications.co.uk/...lshpool-radio/ Under this umberella is Castle Electronics who do repairs and are very well regarded Found the direct link http://www.hamradiosales.co.uk/CASTLE-1A.htm 73 Fred G4BWP Satisfied customer Last edited by dodgy-dxer; 19th Nov 2018 at 8:51 am. Reason: Editing

17th Nov 2018, 4:38 pm	#4
Restoration73 Nonode Join Date: Jun 2013 Location: Surbiton, SW London, UK. Posts: 2,801	Re: Yaesu FRG7 The board shown is the Toko mech filter unit to increase selectivity over the fitted 6 kHz ceramic filter. The two IF transformers on this board are for matching, but the increased filter loss may cause apparent reduction in gain. My preferred method was to switch in the Murata 2.7kHz ceramic filter CFJ455k although care had to be taken to maintain input and output isolation.

17th Nov 2018, 4:54 pm	#5
LyntonP Hexode Join Date: Nov 2018 Location: Greater Manchester Posts: 305	Thanks for the suggestions chaps. I had done some digging on the internet and found the Charlie Tango listing, but my browser would't let me open the site. Ian your link allowed me to look and yes the item in my receiver is very similar. Unfortunately in my case it is mounted upside down so I cannot see any numbers. Can't say I have gone looking for any SSB up to now, but I will give it a go tonight. What I don't like is the fact that the 'on off ' switch is mounted on the front panel. Pity it cannot have been done a little more discreetly. More digging on the web says it is a Toko 455KHz SSB filter. More questions to follow I'm sure Thanks for the help. Spot on sir. I will give it a go tonight. Cheers, Lynton.

19th Nov 2018, 9:43 am	#8
Andrew2 Nonode Join Date: Mar 2010 Location: Dukinfield, Cheshire, UK. Posts: 2,037	Re: Yaesu FRG7 I'm wondering if there is something a bit wrong with the installation of that filter. We can expect a small extra loss, but it shouldn't make the set so deaf. Properly installed a narrow SSB filter can transform the set from 'not very good at all for SSB' to really quite useable. __________________ Andy G1HBE.

19th Nov 2018, 10:35 am	#9
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,431	Re: Yaesu FRG7 If there is any doubt about the filter, either installation or it being faulty, return the radio to standard configuration, repair any faults then sort out the filter. It’s quite possible that a bad filter or install could degrade the radio when it is supposed to be switched out of circuit. __________________ Frank

19th Nov 2018, 11:46 am	#10
LyntonP Hexode Join Date: Nov 2018 Location: Greater Manchester Posts: 305	Re: Yaesu FRG7 Thanks again for the answers and links to reliable service centres. I agree that the filter may be causing a degradation to the performance and it does seem that it is not working correctly. My initial thoughts were to remove it completely. It does look as if part of the circuit board has been scratched away during its installation, presumably to put it in circuit? Since I bought the receiver to listen to broadcast stations and not SSB I think I will remove the device. I will do a little more digging to see if I can find some installation instructions for the filter which may help in returning the set back to original condition. Again thanks for all the help. Cheers Lynton

19th Nov 2018, 3:45 pm	#11
LyntonP Hexode Join Date: Nov 2018 Location: Greater Manchester Posts: 305	Re: Yaesu FRG7 Ok I took the plunge and removed the filter one wire at a time checking if the radio still functioned. Ended up having to put a small jumper wire on the circuit board that seemed to have been modified. What a difference! No longer deaf at the top of the dial, I can tune in SSB easily as the original filter seems to be working, and broadcast stations are bending the needle. Perhaps it doesn’t need an alignment after all? Photos show the jumper wire and the filter and switch after removal. Couldn’t find any fitting instructions on the web so no idea if it had been fitted incorrectly. Thanks for all the help. Might move on to my non functioning Hallicrafters next? Attached Thumbnails

20th Nov 2018, 12:05 am	#12
m0cemdave Octode Join Date: Feb 2009 Location: Bletchley, Buckinghamshire, UK. Posts: 1,219	Re: Yaesu FRG7 I'm not sure if this applies to yours, but a lot of mechanical filters use synthetic rubber foam to float the filter inside the casing. After 30 or 40 years it perishes and either turns to either sticky goo or powder, and the filter then suffers from very high loss. So it wouldn't be surprising if your filter is faulty. I appreciate that you won't want to do this, but for general interest: diehard restorers take them to bits, very carefully, and replace the foam - there are various articles on youtube and the internet describing the method. Adding a narrow filter for SSB is a very common upgrade for FRG7's, and there is a way of doing it using the existing switches instead of drilling the front panel.

20th Nov 2018, 2:06 am	#13
LyntonP Hexode Join Date: Nov 2018 Location: Greater Manchester Posts: 305	Re: Yaesu FRG7 Dave this sounds very interesting. I understand the advantages of a narrow filter and your comment about using the existing switches is intriguing. I will look further on the web but may come back to you on this one. Lynton

20th Nov 2018, 12:36 pm	#14
Keith Heptode Join Date: Jan 2003 Location: Tewkesbury, Gloucestershire, UK. Posts: 693	Re: Yaesu FRG7 Hi Lynton, I fitted an addition crystal filter to my FRG7 which was switched in using the mode switch (can't remember the details). It did make a big improvement to SSB performance but I found that the drift on the rather crude BFO beacme a bit of a problem. Great receiver for AM broadcast bands though - pity there's not much on there now! __________________ Keith Yates - G3XGW VMARS & BVWS member http://www.tibblestone.com/oldradios/Old_Radios.htm Last edited by Keith; 20th Nov 2018 at 12:45 pm.

20th Nov 2018, 1:29 pm	#15
LyntonP Hexode Join Date: Nov 2018 Location: Greater Manchester Posts: 305	Re: Yaesu FRG7 Keith Interesting comments, and I followed the link back to the article on the KW. Great pictures of the filter rebuild, but I think this would be beyond the capabilities of my eyesight and wobbly hands! I did undertake quite an extensive search on the Internet last night for more information regarding mods on the FRG7 but didn’t really find a great deal of information. One chap had come up with a two colour mod for the lock led, but nothing about fitting narrower filters. For the time being I will enjoy the radio as it is, but keep searching for for any further information. Once again thanks for all the help Lynton G4XCQ

21st Nov 2018, 5:48 pm	#16
JanWra1 Tetrode Join Date: Jan 2018 Location: Stockholm, Sweden Posts: 78	Re: Yaesu FRG7 Hi Guys In the early 70´s I had an early FRG7 before the RIT was added and was quite pleased with it, later added the RIT, but didn't do anything abt the filters. However in the late 70´s There were at least 2 modified versions of the Yaesu FRG 7 marketed by Gilfer in New Jersey and some other US company. The Gilfer mod included a couple of Murata filters and one could either buy the radio modified by Gilfer or buy the mod as a kit. For details check the link below. The Gilfer FRG7 was featured in WRTVH some time in the late 70´s if my memory is correct. www.scrid.com/document/218916488/FRG7-Mod-Gilfer Hope this helps. Jan ]

21st Nov 2018, 6:20 pm	#18
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,996	Re: Yaesu FRG7 IMHO there's a typo: it's scribd not scrid ??

21st Nov 2018, 6:34 pm	#19
JanWra1 Tetrode Join Date: Jan 2018 Location: Stockholm, Sweden Posts: 78	Re: Yaesu FRG7 Sorry made a typing error It is : "scribd" And if this doesn't work search for "FRG7 Mod Gilfer" Jan