Trio JR-500S - UK Vintage Radio Repair and Restoration Discussion Forum

QQVO6/40 · 16th Dec 2020, 3:42 am

G'day everyone.

While recovering from serious abdominal surgery I have been looking at "light weight" stuff to keep me entertained. The AR-88LF on the bench will have to wait. A good time to make those test leads I have been putting off for so long.

A month or so ago I had given to me a Trio JR-500S amateur band receiver. Not a lot of info about this name on the net but I discovered that in the USA it was marketed as an Allied A-2516 receiver. Quite a bit of information on the net including a complete manual. Printed all! Beauty!
I have had a look at it and it seems all there but has been "got at" so I will have to go right through it. One thing I noticed was that the previous owner has shorted out the output from the VFO. Power supply needs work as well as there are wires snipped.
I have looked around and the little radio gets quite a few reasonable reviews. Sounds promising.

I have looked at the two threads on this forum about this little set and have taken note of their wisdom / included it in my workshop printout. Quite practical information.

I was wondering if anyone here has any comments good or bad about this little radio?

Thank you in advance.

Cheers.
Robert. VK2ZWZ

HamishBoxer · 16th Dec 2020, 9:28 am

I used to have one of these and I loved it, performed well from what I remember. Certainly worth restoring. This was in the 1970's.

Hope you are recovering well and get around to that AR88 next year, mine is on the bench. Sadly, the days are gone when I could lift it alone!

QQVO6/40 · 16th Dec 2020, 1:36 pm

Hello Hamish and everyone.

Thank you for the good wishes. Yes things are going well. I just have to be careful as it still lets me know if I have been naughty.

I have a good solid turntable for the AR-88LF but I won't risk it just yet.

Just tonight I finished off an Icom IC22A 2 metre FM transceiver and have made a few contacts on it with my radio club. All good. I can put it back in storage fixed.

I was given the JR-500S from a deceased estate. Nobody else wanted it and if I didn't it was headed for the bin. It's valve so no way!
It seems all there and only a tiny bit of surface rust on the chassis. All the valves are there. I have to say for a middle of the road RX the VFO tuning is particularly smooth.
No chance of powering it up till I have gone right through it. I find it unusual that there is only a single diode in the HT power supply giving half wave rectification. Would have to lead to hum problems so there is a mod for me first up.
On looking at it yesterday I noticed that the previous owner has shorted the output from the VFO. Weird??
I have looked on the interweb and found a few short reviews for the United States version (same as the JR-500S) and like your comments Hamish rather good. Sounds quite encouraging so I am looking forward to having a go at it.
I'm lucky as all of the crystals are still in the radio. Yippee!!! I don't have to chase them.
It seems to be a characteristic of radios down here that people whip all of the crystals out of them for some reason. I was recently given an AWA C52820 comms receiver and the IF filter crystal had been removed. WHY

Where am I going to get a 565kc series resonant crystal in a large AWA holder?
A story for another thread further down the log book.

Enough of my chatter.
Cheers all.
Robert. VK2ZWZ.

QQVO6/40 · 19th Dec 2020, 1:34 pm

G'day everyone.

I have only had enough time to take a couple of pics today.
Feeling rather tired. Quite common after surgery.

The radio has a single diode half wave rectifier as per the circuit diagram. It is notorious for adding hum to the audio output. I am going to use a diode bridge but where to put it.
I could put it at the transformer and run the raw DC around the chassis to the filter cap or I could run the raw AC from the transformer via a twisted pair to the diagonally opposite corner of the chassis to the bridge and filter cap.
A strange design feature is the power transformer is on one corner of the chassis and the filter cap and HT distribution is under the diagonally opposite corner of the chassis.
Hmmmmm! Thinks or should that be Huuuuuuummm! thinks.
One way I get pulsed DC with a common earth through the chassis as the negative of the HT supply goes to the chassis.
The other way I get raw HT AC running to the bridge via a twisted pair of wires.
I am sort of leaning towards running the AC to the bridge and earthing the negative at the bridge. This way the AC is balanced and less likely to cause hum issues. A bit like twisting the filament leads on AC powered radios to reduce hum.
How say you?

More to follow.

Cheers all and please stay healthy.

Robert. VK2ZWZ.

Station X · 19th Dec 2020, 2:26 pm

wouldn't it be a good idea to test the radio as it is before modifying the PSU? There could be a show stopping fault elsewhere.

QQVO6/40 · 20th Dec 2020, 12:33 am

G'day Graham and everyone.

The "show stopping fault" has already occurred.
The radio has been "got at" by the mad snipper. The power supply has been disconnected and there are quite a few wires snipped and just hanging elsewhere.
This radio came from a deceased estate and cost me nothing so I have a free reign to get it going again. My comment in a previous post that the radio was "all there" was meant to indicate that all of the major components were present but did not indicate that all of them were connected electrically. It is way better than being handed a cardboard box full of the individual parts and I am not talking of a Heathkit. That is a different story.
Trust me Graham, in around 60 years of working on radios I have seen a lot!
I start at the mains plug and work from there. One domestic radio I saw recently had the earth wire in the mains connected to the active. Even though the radio had a transformer power supply it was definitely a "hot chassis". Surprisingly it did work or so my owner friend told me. I checked it out before 230V got anywhere near it.
My JR-500 has had the power supply snipped so I have to build something. I might as well go with my ideas as there is no point in reconstructing the original circuit and then having to modify it to fix an accepted problem.
One of the other things I have to work out is why the previous owner shorted out the output of the VFO. Not a "bell ringer" for getting a radio to work!

Cheers all.
Robert. VK2ZWZ.

16th Dec 2020, 3:42 am	#1
QQVO6/40 Hexode Join Date: May 2009 Location: Newcastle, Australia Posts: 319	Trio JR-500S G'day everyone. While recovering from serious abdominal surgery I have been looking at "light weight" stuff to keep me entertained. The AR-88LF on the bench will have to wait. A good time to make those test leads I have been putting off for so long. A month or so ago I had given to me a Trio JR-500S amateur band receiver. Not a lot of info about this name on the net but I discovered that in the USA it was marketed as an Allied A-2516 receiver. Quite a bit of information on the net including a complete manual. Printed all! Beauty! I have had a look at it and it seems all there but has been "got at" so I will have to go right through it. One thing I noticed was that the previous owner has shorted out the output from the VFO. Power supply needs work as well as there are wires snipped. I have looked around and the little radio gets quite a few reasonable reviews. Sounds promising. I have looked at the two threads on this forum about this little set and have taken note of their wisdom / included it in my workshop printout. Quite practical information. I was wondering if anyone here has any comments good or bad about this little radio? Thank you in advance. Cheers. Robert. VK2ZWZ

16th Dec 2020, 9:28 am	#2
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,932	Re: Trio JR-500S I used to have one of these and I loved it, performed well from what I remember. Certainly worth restoring. This was in the 1970's. Hope you are recovering well and get around to that AR88 next year, mine is on the bench. Sadly, the days are gone when I could lift it alone! __________________ G8JET BVWS Archivist and Member V.M.A.R.S

16th Dec 2020, 1:36 pm	#3
QQVO6/40 Hexode Join Date: May 2009 Location: Newcastle, Australia Posts: 319	Re: Trio JR-500S Hello Hamish and everyone. Thank you for the good wishes. Yes things are going well. I just have to be careful as it still lets me know if I have been naughty. I have a good solid turntable for the AR-88LF but I won't risk it just yet. Just tonight I finished off an Icom IC22A 2 metre FM transceiver and have made a few contacts on it with my radio club. All good. I can put it back in storage fixed. I was given the JR-500S from a deceased estate. Nobody else wanted it and if I didn't it was headed for the bin. It's valve so no way! It seems all there and only a tiny bit of surface rust on the chassis. All the valves are there. I have to say for a middle of the road RX the VFO tuning is particularly smooth. No chance of powering it up till I have gone right through it. I find it unusual that there is only a single diode in the HT power supply giving half wave rectification. Would have to lead to hum problems so there is a mod for me first up. On looking at it yesterday I noticed that the previous owner has shorted the output from the VFO. Weird?? I have looked on the interweb and found a few short reviews for the United States version (same as the JR-500S) and like your comments Hamish rather good. Sounds quite encouraging so I am looking forward to having a go at it. I'm lucky as all of the crystals are still in the radio. Yippee!!! I don't have to chase them. It seems to be a characteristic of radios down here that people whip all of the crystals out of them for some reason. I was recently given an AWA C52820 comms receiver and the IF filter crystal had been removed. WHY Where am I going to get a 565kc series resonant crystal in a large AWA holder? A story for another thread further down the log book. Enough of my chatter. Cheers all. Robert. VK2ZWZ.

19th Dec 2020, 1:34 pm	#4
QQVO6/40 Hexode Join Date: May 2009 Location: Newcastle, Australia Posts: 319	Re: Trio JR-500S G'day everyone. I have only had enough time to take a couple of pics today. Feeling rather tired. Quite common after surgery. The radio has a single diode half wave rectifier as per the circuit diagram. It is notorious for adding hum to the audio output. I am going to use a diode bridge but where to put it. I could put it at the transformer and run the raw DC around the chassis to the filter cap or I could run the raw AC from the transformer via a twisted pair to the diagonally opposite corner of the chassis to the bridge and filter cap. A strange design feature is the power transformer is on one corner of the chassis and the filter cap and HT distribution is under the diagonally opposite corner of the chassis. Hmmmmm! Thinks or should that be Huuuuuuummm! thinks. One way I get pulsed DC with a common earth through the chassis as the negative of the HT supply goes to the chassis. The other way I get raw HT AC running to the bridge via a twisted pair of wires. I am sort of leaning towards running the AC to the bridge and earthing the negative at the bridge. This way the AC is balanced and less likely to cause hum issues. A bit like twisting the filament leads on AC powered radios to reduce hum. How say you? More to follow. Cheers all and please stay healthy. Robert. VK2ZWZ. Attached Thumbnails

19th Dec 2020, 2:26 pm	#5
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: Trio JR-500S wouldn't it be a good idea to test the radio as it is before modifying the PSU? There could be a show stopping fault elsewhere. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

20th Dec 2020, 12:33 am	#6
QQVO6/40 Hexode Join Date: May 2009 Location: Newcastle, Australia Posts: 319	Re: Trio JR-500S G'day Graham and everyone. The "show stopping fault" has already occurred. The radio has been "got at" by the mad snipper. The power supply has been disconnected and there are quite a few wires snipped and just hanging elsewhere. This radio came from a deceased estate and cost me nothing so I have a free reign to get it going again. My comment in a previous post that the radio was "all there" was meant to indicate that all of the major components were present but did not indicate that all of them were connected electrically. It is way better than being handed a cardboard box full of the individual parts and I am not talking of a Heathkit. That is a different story. Trust me Graham, in around 60 years of working on radios I have seen a lot! I start at the mains plug and work from there. One domestic radio I saw recently had the earth wire in the mains connected to the active. Even though the radio had a transformer power supply it was definitely a "hot chassis". Surprisingly it did work or so my owner friend told me. I checked it out before 230V got anywhere near it. My JR-500 has had the power supply snipped so I have to build something. I might as well go with my ideas as there is no point in reconstructing the original circuit and then having to modify it to fix an accepted problem. One of the other things I have to work out is why the previous owner shorted out the output of the VFO. Not a "bell ringer" for getting a radio to work! Cheers all. Robert. VK2ZWZ.