Ferguson 383A

[petervk2mlg]

I've had this radio sitting round for years. I thought it was time to see if it could talk.
I plugged it in before any preliminary checks at all and was greeted with absolute silence and darkness from all valve heaters and dial lamps.
Checking the power plug indicated no continuity between active and neutral pins.
After that I took the chassis out of the cabinet and checked the on/off switch. This was fine showing continuity when turned to the on position and an open circuit when turned off. I suspected the power plug after that.
Sure enough on inspection, I found that the active lead had become detached from the appropriate pin inside the (Australia) power plug.
Fixing this and turning the set on again produced some signs of life. The valves lit up as did one dial light, and twiddling the volume control produced faint crackles from the 'speaker.
Attaching a length of wire to the external aerial connection did produce some extremely faint radio reception on medium and long wave. Actually all I can receive on long wave here is the local airport beacon - PKS in morse.
I prodded the grid connection of the EL84 with my multivibrator "signal generator" and received good loud sound.
Nothing much was heard when injecting into earlier stages, however.
Voltage readings indicated several resistors had gone very high: R7, the ECH81 screen feed resistor, R13, the EF89 screen feed resistor, as well as R10 the oscillator plate resistor.
R25 the detector/first audio plate resistor was also way too high. Replacing these components did not restore anything of listenable quality, however.
With my ear pressed to the 'speaker, I could just about hear some AM medium wave reception.
My attention turned to C52 - THAT CAP - a Hunts of 0.001uf value.
On my insulation tester it showed no leakage at all despite looking decidedly ropey and cracked. A check on the capacitance meter, however indicated that it was pretty much open circuit - showing a reading of 2.5pf! I was amazed that any audio signal was getting through to the EL84. A new 0.001uf 400 volt capacitor was soldered into place.
The EL84 grid stopper resistor had also gone up to twice its declared value, so I replaced that too while I was in its vicinity.
On reapplying power to the set, good loud and pleasant quality reception was delivered.
FM was a very weak however and that remains to be attended to. I did notice, however, that the only component that was not original in the set was a large polyester 0.47 uf capacitor around the FM detector circuit. This was acting as FM detector reservoir capacitor, a component designated by the Trader Sheet as C45 - a 4uF electrolytic, I didn't think the polyester would be suitable. I didn't have a 4uF electrolytic, but I did have one of 10uF value so I soldered that in place - positive to chassis, of course.
I live in a rural environment where FM reception is not strong, but I will need to look at the FM side of the radio again.
All in all, an enjoyable and satisfying repair.

[Phil G4SPZ]

Well done, Peter. Unusual for a capacitor in THAT position to go open-circuit as they normally go leaky, but worth remembering as a possible cause of low audio.

I'd suggest trying a replacement V1 (ECC85) if available, or at least checking the anode and screen voltages around this stage. VHF frequency changers seem to get tired over the years. I have several good ECC85s that you are welcome to have for the price of postage.

[paulsherwin]

FM sets of that era weren't very sensitive by modern standards. The thinking in the 50s was that most people would use them with a large external aerial, just like a TV set. The original UK VHF network was certainly planned on that basis.

You might want to try the set with a simple one transistor preamp, which will increase the signal by maybe 14dB.

[petervk2mlg]

Thanks Phil. I was given an ECC189. Is this an acceptable substitute for an ECC85? It didn't make the radio run any better on VHF.
Paul, I have tried the set on an outside FM antenna. As the set only goes to 100MHz and my two favourite stations are on 102.7 and 104.3, I tweaked the VHF oscillator trimmer to bring them in. Not ideal I know, but at least I can hear them.
I have two FM antennas on the house and one is decidedly better than the other. It provides me with listenable quality on the Ferguson although there is some distortion, I must admit and tuning is really critical.
The idea of a simple transistor preamp is a good one, I think.

[telstar]

Hi Peter. I have the 382U & 384U radios made by Thorn (Ferguson), which are of course basically the universal mains versions of your model.
I found out that the capacitors (metal foil) known as Hunts mouldseal, were not very good, and the resistors (compared to other radio manufacturer's quality) were also a bit poor. My Bush VHF61 in comparison, works extremely well on f.m internal aerial without having to plug in an outside antenna.
The main bugbear on these Ferguson radios is that the f.m tuner house is so tightly secured that you run risk of accidentally mis-aligning it once you have finished any work inside it. There are grid resistors that could read beyond their tolerances on the UCC85 valve. It is a great shame that Thorn did not copy designs such as Grundig, where you could easily access the insides of their tuners. Having said that, I still like the appearance of these Ferguson radios.
The loudspeakers also require replacement.
Cheers
Mike

[mark pirate]

I have one of these sets, mine is as yet untouched and working, although the cabinet is coming apart at the seams!

My set was fine on AM, but nothing on FM. Replacing the ECC85 bought it back to life, but it needs a good signal to work properly.
You are absolutely correct about the resistors, they are very poor quality, allied to Hunts Mouldseals, I am amazed mine still works

As Mike has said, the FM tuner is a pig to work on (probably why it has sat on the roundtuit pile for so long!).

I wonder if your set was an official export, or if it was brought over by an ex-pat?

[paulsherwin]

Pretty much all foreign valve radios in Oz arrived with migrants. Australia had very tight restrictions on domestic radio imports throughout the valve era. In any case there wouldn't have been much point in trying to export a VHF valve radio to Australia, as FM broadcasting only started in 1976.

[Phil G4SPZ]

Originally Posted by petervk2mlg

Thanks Phil. I was given an ECC189. Is this an acceptable substitute for an ECC85? It didn't make the radio run any better on VHF.

I'm not surprised. Whilst the ECC85 and ECC189 are both pin-compatible double triodes, they are not equivalents in most other respects. As I said, I'll happily send you a couple of good new ECC85s. I would hope the postage cost for a small and lightweight package would not be excessive, even to VK-land! Drop me a PM if you're interested.

[Sideband]

I had a 383A until recently (I sold it to make space for more 40's radio's and tellys). The FM actually worked well but I did do a complete FM alignment after fitting a new ECC85. If you follow the FM alignment instructions exactly, you should get good results.

[petervk2mlg]

Thanks for all the responses.
Yes, Mike I was wondering how I was going to get at the FM tuner unit. The 'speaker on mine is in good shape, unlike the cabinet which is a bit sad.
Mark, I would say that this is definitely a UK set brought in by a migrant. The dial markings are evidence of that. Paul is correct about UK radio imports into Australia although 1974 saw the first FM broadcasts. The ABC started FM broadcasts in 1976 and commercial stations had to wait until 1980 for FM broadcast licences.

[telstar]

Hi Peter. If you start to gain access to the tuner head innards, take it slowly and methodically, and make clear notes on whatever you do. I may have the Ferguson service data for the 384U model, which will probably show better details.
By the way, I wonder if there was a service exchange system for engineers that came across this problem on these radios, remove the old tuner heads and replace them with a re-conditioned one?
Just a thought!
Mike

[Hybrid tellies]

A very interesting write up. I forgot that FM did not come to Australia until 1976.

[petervk2mlg]

Thanks Mike and Simon.
The access to the chassis via the bottom of the radio is a good idea, but access isn't really that great being rather narrow and deep. To service the set I removed the chassis from the cabinet. The radio is not a thing of beauty in my opinion, but I guess typical of its period.

[Phil G4SPZ]

Peter,

The ECC85s are in the post. Good luck!

Phil

[telstar]

Hi Peter.
Just a thought, your radio uses a metal bridge rectifier in the h.t circuit. It may be wise to replace this with a silicon bridge rectifier and a limiting resistor (220 ohm @ 3 watt). Sometimes f.m radios are affected by metal rectifiers, although a.m seems to work o.k.
Give it a try!
Regards
Mike

[petervk2mlg]

Thanks, Mike. Good thought. I did consider changing the rectifier, but placed it on the back burner. You know how it is!

P

[telstar]

Hi Peter. I always replace these items. They may have been alright as new, but they age dreadfully - internal resistance increases!
Cheers
Mike