Aerodyne 52; general repair questions. - UK Vintage Radio Repair and Restoration Discussion Forum

TimS · 19th Jan 2007, 9:40 pm

I have an Aerodyne 52, c 1937. I haven't had it plugged in yet as there is a fair bit to do and check. Its an AC only TRF. 3 valve + rectifier.

Question 1: Mainly out of curiosity, is that TCC cap likely to be original (see piccy below)? Most if not all of the rest of the set appears to be so. If its original I'll keep it in situ and hide some modern bits behind or inside it.

Question 2: What on earth is that rusty metal box with two terminals on top? My multimeter is entertaining the idea that it might be (or was once) a capacitor. This also appears logical because if it isn't I'm missing one of the smoothing caps (no great loss though as the TCC from Question 1 appears kaput and can probably fit two modern caps inside itself).

Question 3: That coil (L15 in the 'Trader' diagram) is open circuit, but how do I work out what to replace it with given that the data just gives a resistance reading, not an inductance value. Its in series with the anode load. Is there much chance of finding a working replacement that is identical or of similar appearance?

Question 4: The mains transformer shows the correct resistances across its various coils

. However it shows around 20Mohm between primary and secondaries.

Is this a big problem? Also given the rather tatty state its in, would you use it? I'm happy sliding heatshrink on to the wires with the decaying rubber insulation but will its inards be OK?

Question 5: Most of the wires (which are more like metal rods in some cases) are covered in the brown braided insulation that you can see in the transformer picture. Its quite stiff, and presumably was more flexible in its younger days. A larger diameter variety (top left of piccy with blue and white wires emerging) has proved itself too brittle to be use or ornament but the smaller diameter variety shown seems OK. Is this a reasonable conclusion or should I be buying a bumper pack or heatshrink to slide inside (there is room)?

-- Tim, also anticipating posting in the cosmetic and finishing section. woodworm, slightly peeling veneer, rusty chassis, disintergrating speaker cloth. Luverly...

JoshWard · 20th Jan 2007, 3:43 pm

Hi Tim, I believe the TCC capacitor would be original (I've found some similar in several 1930's sets). I think the big grey box is a capacitor, I have two similar ones in the bottom of a McMichael Twin Superhet both with 'uf' labelled on the base. Josh.

PWH · 20th Jan 2007, 4:41 pm

The brown braided sticky stuff used as insulation is called systoflex which is woven linen covered in a bitumen type material.

Modern heatshrink will do the trick or you could get some of the original stuff from my website.

The TCC capacitor >something tells me it is not original

The rusty box could be a choke or a capacitor, but capacitors will normally have a value on them.. See if you can get the sevice data from Paul. Otherwise the 'hard way' is to open it up and have a look

The O/C coil well if you are lucky the break will be near the outside and a few missing turns won't hurt. Otherwise take careful measurments of the size of the coil and re wind another with the same size wire to the same physical dimensions and it won't be far out.

Aerodyne · 20th Jan 2007, 6:57 pm

I'd say the metal box is certainly a capacitor. It might house two caps, in fact, with casing common. Just because it isn't obvious from the Trader sheet photo-diagram, don't assume its a 'foreigner' because Aerodyne often varied their component usage to a considerable degree. I've seen TCC 'condensers' fitted as original in Aerodyne receivers, though I can't guarantee this is one such. What is obvious is that the size and appearance suggests the age is correct. L15 is an HF choke, part of the RF filtering network. You might be able to find a suitable replacement or rewind it.
Should make a good restoration project.
Regards
Tony

TimS · 20th Jan 2007, 7:43 pm

I need to look closer in future methinks. Now I look amidst the rust more carefully on the rusty box, although the sides are up to 95% pitted (the metalwork all over looks like its spent its 80yrs in salt water!), one side has '?uir?ead ?ond?nser ?uF A[crown symbol]M' just about discernible. There were a couple of Muirhead wax caps inside also.

Have plugged in the mains transformer with no load. No smells or smoke and the secondary gives about the right figure (280VAC x2). I think I may well be putting a very low value fuse inline with this though...

Aerodyne · 21st Jan 2007, 4:27 pm

My experience with Aerodyne's usual drop-thru mains trannies is that they are pretty robust. Drying out after long periods of neglect is always worth while but I doubt the need for an additional fuse in the manner you suggest. Just be sure there's no short on HT line or within the valve rectifier. I prefer to power up using a test lamp in series until I'm sure there's no likelihood of leaks, i.e. the set functions without excessive hum, lamp sinks to dim and stays that way.
-Tony

19th Jan 2007, 9:40 pm	#1
TimS Pentode Join Date: Jun 2005 Location: Forres, Moray, UK. Posts: 194	Aerodyne 52; general repair questions. I have an Aerodyne 52, c 1937. I haven't had it plugged in yet as there is a fair bit to do and check. Its an AC only TRF. 3 valve + rectifier. Question 1: Mainly out of curiosity, is that TCC cap likely to be original (see piccy below)? Most if not all of the rest of the set appears to be so. If its original I'll keep it in situ and hide some modern bits behind or inside it. Question 2: What on earth is that rusty metal box with two terminals on top? My multimeter is entertaining the idea that it might be (or was once) a capacitor. This also appears logical because if it isn't I'm missing one of the smoothing caps (no great loss though as the TCC from Question 1 appears kaput and can probably fit two modern caps inside itself). Question 3: That coil (L15 in the 'Trader' diagram) is open circuit, but how do I work out what to replace it with given that the data just gives a resistance reading, not an inductance value. Its in series with the anode load. Is there much chance of finding a working replacement that is identical or of similar appearance? Question 4: The mains transformer shows the correct resistances across its various coils . However it shows around 20Mohm between primary and secondaries. Is this a big problem? Also given the rather tatty state its in, would you use it? I'm happy sliding heatshrink on to the wires with the decaying rubber insulation but will its inards be OK? Question 5: Most of the wires (which are more like metal rods in some cases) are covered in the brown braided insulation that you can see in the transformer picture. Its quite stiff, and presumably was more flexible in its younger days. A larger diameter variety (top left of piccy with blue and white wires emerging) has proved itself too brittle to be use or ornament but the smaller diameter variety shown seems OK. Is this a reasonable conclusion or should I be buying a bumper pack or heatshrink to slide inside (there is room)? -- Tim, also anticipating posting in the cosmetic and finishing section. woodworm, slightly peeling veneer, rusty chassis, disintergrating speaker cloth. Luverly... Attached Thumbnails

20th Jan 2007, 3:43 pm	#2
JoshWard Octode Join Date: Dec 2005 Location: Near Stowmarket, Suffolk, UK. Posts: 1,962	Re: Aerodyne 52 - five questions... Hi Tim, I believe the TCC capacitor would be original (I've found some similar in several 1930's sets). I think the big grey box is a capacitor, I have two similar ones in the bottom of a McMichael Twin Superhet both with 'uf' labelled on the base. Josh.

20th Jan 2007, 4:41 pm	#3
PWH Heptode Join Date: Mar 2003 Location: Waiheke Island, New Zealand Posts: 503	Re: Aerodyne 52 - five questions... The brown braided sticky stuff used as insulation is called systoflex which is woven linen covered in a bitumen type material. Modern heatshrink will do the trick or you could get some of the original stuff from my website. The TCC capacitor >something tells me it is not original The rusty box could be a choke or a capacitor, but capacitors will normally have a value on them.. See if you can get the sevice data from Paul. Otherwise the 'hard way' is to open it up and have a look The O/C coil well if you are lucky the break will be near the outside and a few missing turns won't hurt. Otherwise take careful measurments of the size of the coil and re wind another with the same size wire to the same physical dimensions and it won't be far out.

20th Jan 2007, 6:57 pm	#4
Aerodyne Octode Join Date: Jun 2004 Location: Hampton Vale, Peterborough, UK. Posts: 1,698	Re: Aerodyne 52 - five questions... I'd say the metal box is certainly a capacitor. It might house two caps, in fact, with casing common. Just because it isn't obvious from the Trader sheet photo-diagram, don't assume its a 'foreigner' because Aerodyne often varied their component usage to a considerable degree. I've seen TCC 'condensers' fitted as original in Aerodyne receivers, though I can't guarantee this is one such. What is obvious is that the size and appearance suggests the age is correct. L15 is an HF choke, part of the RF filtering network. You might be able to find a suitable replacement or rewind it. Should make a good restoration project. Regards Tony

20th Jan 2007, 7:43 pm	#5
TimS Pentode Join Date: Jun 2005 Location: Forres, Moray, UK. Posts: 194	Re: Aerodyne 52 - five questions... I need to look closer in future methinks. Now I look amidst the rust more carefully on the rusty box, although the sides are up to 95% pitted (the metalwork all over looks like its spent its 80yrs in salt water!), one side has '?uir?ead ?ond?nser ?uF A[crown symbol]M' just about discernible. There were a couple of Muirhead wax caps inside also. Have plugged in the mains transformer with no load. No smells or smoke and the secondary gives about the right figure (280VAC x2). I think I may well be putting a very low value fuse inline with this though...

21st Jan 2007, 4:27 pm	#6
Aerodyne Octode Join Date: Jun 2004 Location: Hampton Vale, Peterborough, UK. Posts: 1,698	Re: Aerodyne 52 - five questions... My experience with Aerodyne's usual drop-thru mains trannies is that they are pretty robust. Drying out after long periods of neglect is always worth while but I doubt the need for an additional fuse in the manner you suggest. Just be sure there's no short on HT line or within the valve rectifier. I prefer to power up using a test lamp in series until I'm sure there's no likelihood of leaks, i.e. the set functions without excessive hum, lamp sinks to dim and stays that way. -Tony