Trio JR310 Receiver.

[ms660]

Originally Posted by g0hze snowy

IF board V1 as follows
pin1=0v, 2 and 4 are chassis, 3=0.002v, 5=187v, 6=126v, 7=8.75v
V2,
pin 1=9.7v, 2 and 4 are chassis, 3=0v, 5=189v, 6=146v, 7=9.82v

Are those cathode voltages of the IF amplifier valves high with the RF gain control set to maximum gain?

Lawrence.

[g0hze snowy]

Hi Lawrence
Yes, RF gain is at max, just now filling in the blanks on the circuit diagram, interconnecting wires non-existent on some parts of it, very confusing for an ex-rockape, just hope i dont draw in too many extra's ha ha

[ms660]

With the RF gain set to max. the cathode bias voltages for the IF valves would normally be determined by the voltages across R4 and VR4 (the S meter adjustment)

Lawrence.

[g0hze snowy]

a little more advice please, are the 1n60 diodes germanium or silicon, parts list just id them by their part number.

[ms660]

Germanium so far as I know:

https://www.mikeselectronicparts.com...-datasheet.pdf

Lawrence.

[David G4EBT]

Originally Posted by g0hze snowy

a little more advice please, are the 1n60 diodes germanium or silicon, parts list just id them by their part number.

Germanium, though confusingly, the datasheet refers to them having a 'metal silicon junction':

https://www.nikom.biz/pdf/1N60_DEC.pdf


If you need any, there are lots of suppliers on eBay, typically about £2.50 for ten post-paid.

Look for '10 x 1N60P Germanium Detector Diode FM Am TV Radio Detection'

[g0hze snowy]

Thank-you Lawrence and David, as you rightly pointed out they are listed as something other than germanium.
Still puzzled with this circuit, dont think i have added any additional lines to the circuit, makes it even more confusing for me ha ha.

[frsimen]

The high voltages you are measuring on pin 7 of IF valves 1 or 2 are an indication of something wrong around the RF gain control. The resistance from the slider of the RF gain control to chassis should be close to zero when the control is fully clockwise. Check that is the case for your control, then check the wiring back from the slider to R4 and VR4.

Paula

[g0hze snowy]

Hi Paula, nice to hook up with you on something different than the 9081!, The RF gain control seems notchy, been looking to obtain a replacement, dual gang pot, 5k (b) for the RF and 500k (a) for the AF, i have cleaned it with' DETOXIT' , not advertising, honest. slightly off full turn clockwise i get a movement on the gues(s) meter, i think i will graft in another pot as a test setup.
Snowy

[g0hze snowy]

update on the JR310, have changed some out of spec 'R's and a couple of 'C's13/14, now i can get a signal thru' the radio, needs a lot of signal but still the guess meter dosen't want to play. The swamp resistor was 100ohm when schematic shows 82ohm, changed, no different. The 's' meter zero pot works as the needle moves across the scale.
Have changed the valves to achieve some semblance of the radio working.
Any further advice please.
G6TANuki, your item ready for the post office.

[Junk Box Nick]

I have owned a JR-310 from new. The S meter was never that lively. I used it as one half of my HF Tx/Rx set-up and gave reports using my ears as per the aural system.

[g0hze snowy]

JBN, my 'S' meter is positively lethargic compared to my paragon tuned to same signal.
Injecting a signal from my 2022e makes no difference even at -35dBm, just a thought, the meter doesn't look to fit the aperture properly, me thinks it has been changed, will have to see what the parts list actually list.

[G6Tanuki]

If the gain/sensitivity seems low, one thing to be aware of is that a lot of Japanese manufacturers in the 60s and 70s slathered their tuned-circuits with a kind of wax that has not improved with age; it breaks down/absorbs moisture and then ruins the 'Q' of the coils. In some instances it can introduce so much loss that oscillators don't oscillate !

Warming the wax with a hairdryer until it becomes sticky, then wiping it away with a cotton-bud can sometimes bring a significant improvement. I had a Trio 9R-59 whose highest-frequency-band's local oscillator wouldn't oscillate; de-waxing restored oscillation. I then de-waxed the RF-stage coils and got a noticeable improvement in sensitivity too.

[Junk Box Nick]

Originally Posted by g0hze snowy

just a thought, the meter doesn't look to fit the aperture properly, me thinks it has been changed, will have to see what the parts list actually list.

Post a photo – I’ll soon tell you!

Listening to the seemingly better signal strength reports given by other stations I used to wonder if my 310 was a bit deaf. One night a pal brought up his Yaesu FR50B and we had them side by side. They seemed on a par but his meter was flicking all over on the same signal.

G6Tanuki’s comment re the wax is worth noting. My 310 still seems fine. It has had very little done to it but has been well cared for and stored in good conditions.

Has your 310 a narrow filter or had any of the bandwidth filters changed or does it just have one filter? The 310 was typical of Japanese sets of the time with add-ons available. Mine has never gained a calibrator or a band in the EXT position.

I’m fond of mine and realise it was a good set. My father would be pleased I still have it to enjoy – it cost him a lot of money!

[Techman]

I've had one of these for a few years now. It's permanently plumbed into a low down cupboard in the living room with other radio related bits, so if I want to listen to anything I just open the cupboard for the duration and when finished the cupboard just gets closed and the radios disappear. I got given the set a few years ago and I've done very little to it, and certainly nothing since a week or two after I first acquired it. I'm surprise that you needed to replace all the valves, are you sure they were all faulty?

Mine runs for hours sometimes with virtually no drift after first warm up. I used to use a small speaker connected to the rear terminals, but now find it better to keep a set of headphones on a long(ish) lead plugged into the front socket and find that just leaving them out on a table gives adequate volume in the room. If I do happen to put them on I quite enjoy the 'warmth' of the low level mains hum that these sets were born with, just having to keep the volume low enough when 'clicking' any switches!

The 'narrow' filter works really well and still maintains good audio, unlike some others. Mine has the advantage of having top band on the 'EXT' position. It also has an FM conversion on one of the AM positions that someone in the distant past has fitted. There's also a calibrator that someone's previously fitted and I've never worked out how to use it and when I posted about it on here a few years ago, neither did anyone else.

I've found that it's certainly as sensitive as a relatively modern Yaesu that I had here a while back, but will concede that it does fall off a bit in this respect up at the higher frequency end of its bands - but it does date from 1969/70, so what do you expect. The only other downsides are that it's 'banded' rather than continuous coverage, but that's due to its age and being crystal controlled. The other thing is that the backlight on the dial doesn't illuminate the front of the scale, making it difficult to read when trying to tune it with it being on a shelf in the back of a dark cupboard.

[Junk Box Nick]

Compared to most commercially available sets of the time the JR-310 had superb stability. This was mainly down to the hybrid construction with a solid state oscillator.

I got mine in 1971 and the stabilty was joy after chasing stations with the tuning dial on other receivers and astonished those who hadn’t seen a 310 in action. I remember turning it on with the AF gain up waiting for a (usually) SSB station to appear and then barely change in pitch.

[g0hze snowy]

All valves changed for new ones (some of them turned out to be faulty!) then old valves reused till radio stopped working, that bottle consigned to the waste bin, but even the new 2 x in the if/rf board failed to work. Not met NOS faulty items before but considering their age i suppose it is to be expected.
Just the OEM filter fitted.
Will remove the ali shields from the IFT,s and check, got a better audio response by changing c13 and c14 on the rf/if board as well as a 'R' that had changed in value.
Slow progress but progress, nevertheless.

[Techman]

I don't know how you know that two of the replacement valves are faulty without doing methodical and proper fault finding - let us know what tests you have done to come to that conclusion, unless you found that the old valves worked and the new ones didn't.

[g0hze snowy]

Techman, that's what i did, substitution, the 2nd set of replacements worked whereas the 1st lot didn't.

[Techman]

There certainly are folk out there selling faulty valves!