Trio 9R-59DS repair

[Superhet Si]

I have just bought a Trio 9R-59DS as an on going repair.
The initial fault has been repaired, a dirty band change switch was causing loss of sensitivity.
But the scale linearity of the tuning dial is a mile off. Looking at the front end trimmers there are signs that a phantom dabbler has been at work.
As I can't find a service manual, I have performed the following adjustments.
First I peaked the IF at 455 with a AC meter on the output , there was quite an improvement just from doing this.
Then moving to the rf section I adjusted the oscillator cores at the low frequency end, the oscillator trimmer to on the HF end to correct for tracking, and then antenna trimmer for best sensitivity.

My only remaining question is how do I make adjustment to the trimmers and cores marked "RF"? It looks like these match the RF amp to the mixer stage, is it a case of peaking the cores at low frequency and the trimmers to the top end?

This is a lovely radio, very stable and little drift although it does seem to distort on strong signals.

[Station X]

PM me your email address and I'll send you the service manual. Size about 3 Meg.

[G0FZF Carl]

Hello Graham. I have recently purchased two 9R-59D receivers from a well known web site which will require a lot of TLC to bring them back to life, therefore I am looking for a service manual to restore them. Please could you also send me the service manual.

[Station X]

No problem. You'll need to send me a Private Message (PM) with the email address you want it sent to though.

[David G4EBT]

Not sure if it's been mentioned on the forum before, but there were three articles in Radio Constructor magazine by Martin Lindars - one in October 1970, the other two in March and April 1971, concerning modifications that could be made to improve performance and to add features. The series referred to the Trio 9R59DE, which I think was virtually identical to the 9R59DS, because I'd just bought a 9R59DS at the time and did all of the mods. I later sold the radio and don't have the articles any more. (I was lucky enough to have the matching speaker at the time, which are something of a rarity nowadays, though due to its popularity, 9R59DS receivers often pop up for sale).

The mods as I recall consisted of moving the output transformer to below chassis to give better screening from it picking up hum from the mains transformer, and fitting a small smoothing choke in place of the resistor across the smoothing/reservoir caps. I think there was also a valve base already fitted to the chassis to fit a voltage stabiliser, and the article included a mod to fit a crystal calibrator. There were other mods too, such as improvements to the IF/RF stages if memory serves me right, but without the articles to hand, I'm not sure what those mods were. (None of the modifications affected the cosmetic appearance of the set).

I had my 9R59DS for about five years and was pleased with its performance - helped by it having an RF stage - and I rather liked its appearance and still do. The chassis layout is nice and roomy, making it easy to work on. Like any single-conversion superhet, on the higher frequencies image rejection is poor, but that is the trade off with simplicity of design and not a shortcoming of this particular model.

Hope that's of interest.

[CambridgeWorks]

If it is any use, I have a pdf of the Oct 1970 and March/April 1971 mods.
Just send me a pm for a direct e-mail with attachments. I think they are the
Anyone else needing them may also pm me for a copy.
73, Robin

[Bobdger]

Hello Graham.
I have recently purchased pair of 9R-59D receivers from a car boot sale
Please could you also send me the service manual.
Many thanks Bob.

[Station X]

You'll need to PM me your email address.

[Phil G4SPZ]

It's nice to see so many of these receivers coming into preservation. I had a right game fixing mine, but it works well now. I also recently managed to but a matching speaker, which cost me more than the radio did!

Going back to Superhet Si's original question about scale linearity during alignment, this baffled me too until it dawned on me that the alignment must be carried out with the bandspread capacitor set to minimum capacitance...

[Biggles]

I have one of these lurking around in the shack in working order also Phil. It is in good cosmetic condition and even has the extension speaker. It didn't need much doing to it when I bought it.
Alan.

[Radio Wrangler]

If it's nicely stable, then it must have the voltage regulator tube fitted that was just a spare hole for an aftermarket mod in many of these sets.

David

[Jon_G4MDC]

I did that mod on mine years back.

ISTR I also replaced the multi stranded wire in the VFO section with solid, well supported at several different points along the length, to get rid of the wonderful microphony it had at first.

Beware on the HF range of the VFO crossing sides of the IF.
It's possible to adjust LO on the wrong side at the top end so it goes very deaf in the middle.

[David G4EBT]

It’s been mentioned before, but might be worth repeating, that there was a series of excellent articles in Radio Constructor Magazine on improvements and modification to the 9R59DE. I had a 9R59DS back in 1970, which as far as I could tell was identical to the ‘DE’. I carried out most of the mods, providing worthwhile improvements and additions such as the crystal calibrator. Lovely set, for which I had the matching speaker. Happy days!

Like all single superhets it had the limitation of image reception, so at higher frequencies you received the same stations twice. Makes the bands sound busy!

The first Radio Constructor article was in October 1970 and covered mods to the PSU, screen grid resistors, RF gain control, oscillator stability, and addition of the crystal calibrator. This issue of Radio Contructor can be downloaded free from here:

http://www.americanradiohistory.com/...RC-1970-10.pdf

There were two further articles in March 1971 and April 1971, which covered a further eight modifications and alignment information, which can be found here:

http://www.americanradiohistory.com/...RC-1971-03.pdf

http://www.americanradiohistory.com/...RC-1971-04.pdf

It’s quite a large set with not a great deal inside it, so there’s lots of space to work under the chassis. It’s much discussed and there are numerous youtube videos on internet which are helpful and instructive. They crop up quite often at reasonable prices and in good condition, very occasionally with the less common matching speaker. Each time I see one I’m sorely tempted, but so far, common sense has over-ruled nostalgia!

Hope that's useful.

[Valvewhiz1]

Hi David,

I have one of these sets, my third after selling two previous ones, the radio constructor articles look very useful.

I like you like the look of them, the latest one cost around £35 with the matching speaker..

Regards

Amanda M0 DZO

[David G4EBT]

Hi Amanda,

Nice to see a post from you on the forum after such a long break!

I wonder if you got that one from the NVCF? (Didn't see you, but I'm sure you'll have been there!). I saw one there for £45.00 complete with speaker in very nice condition. For reasons of nostalgia, I was musing about it with the seller and he said 'it's got to go - you can have it for £35.00 if you're interested'. Quite a bargain, and very tempting, but I'm on a mission to de-clutter, so, with my 'sensible head' on I had to pass it by.

The mods in the Radio Constructor series made a worthwhile improvement in the performance of the one that I had back in 1970.

[Valvewhiz1]

Hi David,
Yes, I went to the NVCF didn't buy anything apart from a 4 pole 3 way nos switch.

Up to my eyes in amp repairs / mods and tape echo repairs, mods, refurbs etc.

I've had the 9r59ds for a few years now, bought it at a local rally in mint condition with the matching speaker for 35 quid.

I've been pulling out sets from my collection one at a time lately and running them up and got to the 9r59..

Also refurbing an RCA AR80 which has been a long term project for a friend.

Regards

Amanda..