1964 Stella ST160A AM/FM 7 valve radio

[howard]

Hello again,

I won this Stella ST160A MW/LW/SW/VHF 7 valve radio (dated inside 4/2/64) at the July Wootton Bassett auction for £8. Cosmetically it was in excellent condition with a few very light scratches along the top rear edge, and a small piece of lacquer was dislodged on its right hand edge. When I got it home I tried it and it worked, and it sounded quite good too but it did lack sensitivity on FM. One thing I noticed was that the magic eye when indicating optimum reception of a station on FM didn't coincide with the optimum audible reception so that needed attention. I stuck the piece of lacquer back straight away and polished over it with Topps wood polish and that's virtually undetectable now.

I took the back and bottom covers off to find a huge replacement output transformer had been mounted on the end of the chassis - it's original transformer was still in place and still partially wired up and was acting as a choke. New pieces of wire had been attached to the wiring which had been disconnected from the original OT with tape wrapped around the joints and then attached to the new transformer - much of the tape was peeling off.

https://www.vintage-radio.net/forum/...0&d=1183376417
https://www.vintage-radio.net/forum/...2&d=1183391128

The original cables from the OT to the loudspeaker had been replaced with long pieces of silicone sleeved wiring. Also, the mains lead has been replaced and rerouted, but a chunk of the original cable remained in the set inside a sleeve. I took out the chassis and cleaned off all the dust, cleaned the pots and valve pins with switch cleaner and replaced all the sponges and strips of felt around the dial. Noone keeps the service data for this set but I gather from another thread here that this set is closely based on the 1959 Dutch built B4X92A set and the circuit diagram for that I obtained FOC here ...

http://66.49.188.60/philips/b4x92a.html

I wasn't happy about the way this set had been repaired so I asked on the forum if anyone had a suitable spare Philips OT for it but unfortunately noone had one. So I then bought a new OT from RS for it as recommended by a forum member and took it and the set over to Ron Bryan for evaluation. Ron reckoned that the RS transformer was not entirely suitable as it had no feedback windings on the secondary, and the primary was not split into two separate sections, so I decided then to take an identical OT off my unrestored B4X23A plano set, which sounded awful (probably duff speakers).

Ron did all the work on this ST160A set. Digging around revealed a new fuse for the output transformer had been fitted but was completely the wrong value, and the ECH81 anode 2k2 resistor which had burnt out sometime in the past had been bridged with a replacement 3k3 resistor, but was still in circuit. There was also evidence of something caustic having been dropped into that area which had caused minor damage to some of the wiring. The original and large replacement OTs were removed and the OT from the B4X23A fitted and all the wiring to it put back in place. Also the 500mA OT fuse was replaced with the 63mA one found in the B4X23A. The remains of the original mains lead were removed and the replacement lead then correctly rerouted. The dead 2k2 and replacement 3k3 ECH81 anode resistors were removed and replaced with a 2k2 as per the Philips B4X92A circuit. The components slightly damaged by solvent were cleaned up, and one piece of wiring needed replacing. There was some hum coming from the set so we tried replacing the EABC80 valve which improved it slightly but not entirely. To sort out the out-of-sync EM84 magic eye, Ron realigned VHF which sorted it out as well as improving FM sensitivity. We then reassembled the set, after replacing the wires to the loudspeaker with some more original looking wiring and sticking back one of the tone buttons. A set of brand new screws were used to secure the rear cover which we obtained from a shop in Guildford called Margnor Fastners Ltd., whose website is here

http://www.margnor.co.uk/index.htm

I finally cleaned and polished up the cabinet with some Mr. Sheen and it really is in excellent cosmetic condition. It works well now, sounds excellent on strong FM stations (although on full bass it can sound a little bloated at times), and manages to pick up weaker stations OK too, and it also works very well on AM. A very nice radio then and I suspect one of the last valve sets built by Philips.

Howard

[howard]

And here are the replacement self tapping screws from Margnor, same size heads but with slightly coarser threads than the originals, but it's nice to have a matching set of rear screws as the ones found fitted to this set were all sorts ...

They're only a few pence each so if anyone needs any send me a PM.

Howard

[Sideband]

Hi Howard. I remember your original posting about this set and the bodged output tranny. These are beginning to turn up now and they always seem to be good performers. I am fortunate enough to have a completely original sample in almost mint condition because it spent most of it's early life in a box.

Sounds as if yours has had a hard life but at least it was preserved albeit with poor repairs enabling you and Ron to do a good restoration on a fine set.

It's very strange why correct service information seems non-existant on this set. I put it down to relatively small numbers made and being only supplied by 'specialist' dealers.....yes the 1964 date would probably mean one of the last valve receivers made. I have a theory that Philips found a number of chassis in storage and decided to use them for their Stella brand. I doubt that any manufacturer would have started a new production line for a wired radio chassis in 1964 when most had changed over to printed circuit. Alternatively perhaps Holland had 'overproduced' the B4X92A and were left with a surplus which they sold off under the Stella brand.

Anyway whatever happened, it's a fine set so use it and enjoy it!


Rich.

[GJR 11L]

I'm one of the other ST160A owners on here and mine, like many of the sets, has needed no repairs at all. Yet!

The bass is a bit overpowering with the bass boost at maximum yet too thin with it at minimum, but that is my only criticism of the sound quality of an otherwise lovely set.
I had thought about fitting a pair of Harry Moss dual-cone speakers in series, as they are incredibly similar in spec to the original pair, to mine as this could be done without making any irreversible alterations, but I got used to it as it is and haven't bothered. The beneift that I thought would be gained from doing that would simply be that the Harry Moss ones have a modern suspension ring around the woofer.
I have plenty of other devices with single EL84 audio and similar output t/x and on that basis alone, I'm sure that it's the speakers that are responsible for the bass being a little less than perfcet.

[howard]

Originally Posted by Richard_Newman

It's very strange why correct service information seems non-existant on this set. I put it down to relatively small numbers made and being only supplied by 'specialist' dealers.....yes the 1964 date would probably mean one of the last valve receivers made. I have a theory that Philips found a number of chassis in storage and decided to use them for their Stella brand. I doubt that any manufacturer would have started a new production line for a wired radio chassis in 1964 when most had changed over to printed circuit. Alternatively perhaps Holland had 'overproduced' the B4X92A and were left with a surplus which they sold off under the Stella brand. Rich.

Hello Richard,

We thought this set was probably built from 'left overs' as well as it is so similar to the Dutch B4X92A which was built 4-5 years earlier, and even its wooden case and tone buttons are very similar.

Originally Posted by GJR 11L

The bass is a bit overpowering with the bass boost at maximum yet too thin with it at minimum, but that is my only criticism of the sound quality of an otherwise lovely set.

Hello John,

This one sounds spot on without bass boost, and on BBC radio stations generally sounds fine even with bass boost, it's on some commercial pop music stations where it sounds too heavy in the bass. I've found my Philips bi-ampli plano set is the same, but the Reverbeo is fine but then that has larger loudspeakers and enclosures. The B4X23A donor set sounded awful with bloated bass, boosted or not.

Howard

[Robert Darwent]

Hello Howard

You and Ron have done a top job there, well done!

I'm not familiar with this set, but it does remind me of my Bush VHF61 and if it works and sounds anything like that set it will be really good!

It looks like you had quite a 'bodger' at work there. Obviously he must have had a fair amount of knowledge to get the set up and running like it was, but didn't care too much about preserving originality or just making it look right!

Glad the set is back to looking as intended and working so well now. Just superb!