NEWBEE

[Glynn_Gotech]

Hi everyone, I am very new to this I'm an electrical engineer specialising in control systems, I recently bought a radio of eBay GEC BRT165 with a view to turning it into  a bluetooth  receiver, however having seen it think i might like to restore it, I have not attempted any thing remotely like this since my apprenticeship days over 40 years ago. Any advice you have will be greatly received.

[boater sam]

There is a thread about your model https://www.vintage-radio.net/forum/show...p?t=151172

Its a communications receiver rather than a domestic wireless, very nice too. An adventurous first restoration but good luck.

Convert something common and less desirable to bluetooth if you must.

[Mike Watterson]

BRT165 sounds wrong, almost all GEC are BCnnnn (four digits), at least 1935 to 1960. Though some "Commercial" sets (Military, Marine and others) might be BRTnnn

Replace any paper dielectric caps between anodes and grids (leakage destroys following stage / audio transformers), screen grids to 0V (reduces gain dramatically) and across mains or HT or audio transformer primary (can short).
I'd do "bluetooth" by using a Gram input (2 x33 Ohms and a 3.5mm socket), or for live chassis sets a low power AM TV with loop beside it fed by 3.5mm jack. Sets with FM are no problem as a €6 FM TX to connect phone/MP3 to an FM Radio can be higher quality than Bluetooth and can be fed with a €10 BT receiver.
Leakage on the HT Electrolytics can be a problem. One strategy is to remove valves and feed them via 30V current limited PSU (< 50mA) and only replace if leakage doesn't drop to less than 1mA (leave in place and cut + lead, solder small new one to -Ve tag and sleeve +ve connection).

[Mike Watterson]

Actually the ONLY BRT models listed at the Radio Museum are:
https://www.radiomuseum.org/r/gec_brt400.html Maybe 1948
https://www.radiomuseum.org/r/gec_mottag...400es.html Maybe 1960
https://www.radiomuseum.org/r/general_el_brt400k.html Maybe 1964

None include a loudspeaker, which is common for this type of receiver that often was used with headphones (often for morse) or an optional speaker. Most 1935 to 1965 domestic radios will sound better. Especially ones in a wooden cabinet. Bakelite was often used to produce cheaper sets.

[Glynn_Gotech]

Hi All

It is a GEC BRT165, looking on the net I think it is a 1955 model due to being VHF only and the light program being moved to 89.1.

The BRT400 is a totally bigger Beast.

The chassis is GEC and I’ve found loads similar look Bc6144 5244 5243 3248

It has a separate power supply rack that non of the bcxxxx have see link to photo's

https://www.ebay.co.uk/itm/bakelite-gec-radio-1950s-/254349271842?hash=item3b3865e322%3Ag%3A-woAAOSwgW5dbpsG&nma=true&si=t1SeSC0f3XpRkRwi5bLSW%252Bx0zQo%253D&orig_cvip=true&nordt=true&rt=nc&_trksid=p2047675.l2557

I am enjoying the Detective work but I am running out of places to look I really need a Service record or a Drawing to start the restoration, I could trace out the circuit but being a novice on the drawing there would be loads of black boxes where I wouldn't know what the KIT was or the test voltages should be.

[Doodlebug]

DON'T switch on.

Many beginners switch their sets on first, before checks mentioned above and some then say, there
was a hum and dial light came on, not realising the internal damage they may have caused,

[Glynn_Gotech]

Hi Doodlebug
I have not got the radio yet its arriving this week, the power cable has been cut off by the previous owner, she had had it for 10 years as an ornament, who knows what happen before then, but I'm guessing you have to expect the worse, I have been cramming on you-tube where steelcity321 has been going through the steps on a GEC bc5445 he does stress to do a complete power down check, change any electrolytic caps and to check the tolerances of the resistors prior to switching on, if you know of any practical books that would assist with this that would be good.

I've posted on vintage Radio Repair and restoration site and the consensus is "that this set is a rare beast! It certainly looks a bit cobbled up in a hurry albeit professionally."

Mike Watterson I have heard  that trying to get bluetooth working with an existing Radio can cause interference issues, so my first thought was to keep the two circuits totally separate have a three position double throw switch
1) Power to Radio
2) OFF
3) Power to Bluetooth
even to the extent of fitting a separate speaker what do you think, it does all depend on space the radio has priority, and I guess I'm a long way from doing the bluetooth work especially if I can't get drawing for a BRT165 and have to try and reverse engineer the project.
Thanks every one for your help so far very much appreciated  Glynn

[Mike Watterson]

There is no issue with a separate receiver and using a Gram/PU input. Almost all were for high level (not magnetic) and unequalised.
I've rarely had to change resistors, only if performance was bad. The biggest issue is the 1nF to 0.5uF paper dielectric capacitors, no matter if Modseal, card & wax or micromite alloy cans with rubber bungs. The leakage on them destroys output valves, audio transformers, power rectifiers and mains transformers if the other bits don't fail first. Faulty electrolytics that don't reform with 30V via a current limit are rarer.

I'm sure that is a rare set. Though rarity is almost unrelated to cash value for radios. It's fashion that sets the price of the expensive models.