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Old 17th Jul 2020, 7:56 pm   #1
PaulR
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Default McMichael 135s - a comparison.

Over the years I have bought two 135s but, unfortunately, only one set of legs!

I restored them both electrically but the mains transformer on one of them burnt out after some use. They have both been relegated to the loft as there isn't really space for them downstairs, but I looked at them again when I was having a clear out. Although the same model with identical chassis the cases are somewhat different as the following photos show. The earlier one has square back edges, a removable inner top, veneering around the edges of the speaker cutouts and a ply back cover. The later one has cut away back edges, the main case made as one piece, brown paint around the speaker cutouts, veneering around the edge of the lid and a cardboard back cover.

They both had opaque brown varnish in not very good condition over the nicely veneered case so I decided to re-finish the case of one of them. As the earlier one had the removable inner top I thought that would be the easier one to do. The veneer on this was also in slightly better condition.

I stripped the lacquer using a painless paint stripper (compared with Nitromors of which a have quite a lot). This brought it off well but needed to be cleaned using water instead of the white spirit I use with nitromors. This meant I could not use wire wool. I used a stainless steel pan scrubber instead which was a little coarse. Having gently smoothed the lovely figured walnut veneer I used American Walnut stain followed by several coats of Danish oil. French polish would have given a better finish but I just don't have the skill to apply this adequately. I polished the finish using Brasso followed by wax polish and I think that the result is acceptable given my level of competence.

The chassis of the set I re-finished is the one with the burnt out transformer and I am trying to justify the cost of having it rewound, but as I already have a good transformer I am finding this difficult. I want to keep the serial numbers correct to the case in view of the difference in case design so if I don't get a new transformer I will probably swap the the one from the newer chassis so the correct one works. It would be a shame, though, if the other one got scrapped just because of a duff transformer. Something to think about!

Anyway, the point of the thread was more about the differences in two radios which had a fairly short production run until the 137 came out. I don't know whether the 135 and 137 were produced concurrently for a while as the story of the one we had when I was a child was that it was bought for my grandfather when he retired in 1938. It may have been that it was old stack in the shop it came from but I do remember my mother saying that, as a teenager, she really wanted the radiogram version which was in the same shop at the time.
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Old 17th Jul 2020, 7:58 pm   #2
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Default Re: McMichael 135s - a comparison.

Some more photos. The original speaker cloth was on good condition, by the way, so I washed and replace it
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Old 18th Jul 2020, 11:14 am   #3
Geoff 555
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Default Re: McMichael 135s - a comparison.

Hello I have both the 137 and 135. The 137 has aways been 100% quiet without any hum.
The 135's transformer has dropped some wax and has aways had a hum, C's and R's replaced as neccessary, so it seems to me that the 135 transformer is a weak point.
As you have one with a burnt out transformer then perhaps a member which knows transformers would care to comment?
All the best.
Regards.
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Old 18th Jul 2020, 12:55 pm   #4
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Default Re: McMichael 135s - a comparison.

That is interesting regarding the hum. This always had dripped wax visible under the transformer but the later one does not. I wonder whether they beefed up the transformer for later models.

Does the 137 have the same back corners as the later 135?

My working 135 has a hum which starts as soon as the rectifier warms up. I had something similar with my 365 and I cured it by adding an external smoothing choke instead of using the speaker field winding. Maybe the hum bucking coil doesn't work as well as it could. With large value capacitors available now I think we are a lot less tolerant regarding hum. I notice that I had put a 16uF smoothing capacitor in place of the original 8uF in the now not working one. The reservoir is still 8uf. I wonder whether this also hummed. I cannot really remember.

I asked Ed Dinning ages ago about rewinding the transformer but never pursued it as I had nowhere to put the set and had recently been given the 365. I am still pondering what to do about it!
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Old 19th Jul 2020, 9:54 am   #5
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Default Re: McMichael 135s - a comparison.

Hi the back corners on the 137 are square and the ones on the 135 are concave. Early or late sorry I don't know the differences.
Cheers.
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Old 19th Jul 2020, 12:18 pm   #6
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Default Re: McMichael 135s - a comparison.

Interesting. I wonder whether I have got them the wrong way round. I assumed that the one with the ply back and more attention to detail such as veneered speaker cut out was the earlier one, but if the 137 has square back corners I may be wrong. I will check the serial numbers.
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Old 19th Jul 2020, 2:04 pm   #7
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Default Re: McMichael 135s - a comparison.

Well, the serial number of the one I thought was the older one is 1988915 whereas the other one is 162.627.

I am still not certain which is the older one in view of the difference in the format of the numbers. The 198.. one is punched into the plate whereas the 162 one is part of the printing itself.

Here are photos of the front of them. The flash makes the un-refinished (first) one look lighter with more visible grain but it is actually a lot darker and it is difficult to make out the grain
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Old 19th Jul 2020, 3:52 pm   #8
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Default Re: McMichael 135s - a comparison.

Interesting ,I have a 135 , with no stand , but found one in a junk shop , someone had made a what looked like a sewing box using the lid off the radio, the stand has square back corners , where as the radio has concave back corners. the speaker cut outs are not veneered just stained, Mick.
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Old 19th Jul 2020, 4:44 pm   #9
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Default Re: McMichael 135s - a comparison.

The stand for mine has square corners but there are bits of metal covering the parts where the concave radio back fits. It came with the concave one so it was possibly a modification to make the stand look as if it was intended to for the set.

It would be interesting to know the serial number of yours, Mick, if you get the chance. I seem to remember a member of the forum collecting McM serial numbers some time ago.
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Old 19th Jul 2020, 10:34 pm   #10
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Default Re: McMichael 135s - a comparison.

Hi Paul no problem the serial number is 158636 cheers Mick.
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Old 20th Jul 2020, 9:05 am   #11
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Default Re: McMichael 135s - a comparison.

Thanks Mick. That doesn't really fit in with either of mine! Ah well it's a bit of a mystery.
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Old 21st Jul 2020, 10:43 am   #12
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Default Re: McMichael 135s - a comparison.

Hi the 137 has a Lion on the brass lite cover on the lid and vaneered edges to the speaker cut outs, the 135 has the initials MH on the brass cover, with brown painted edges to the speaker cut outs.
Cheers.
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Old 21st Jul 2020, 12:13 pm   #13
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Default Re: McMichael 135s - a comparison.

There doesn't really seem to be any consistency to the finish. My assumption that the painted speaker cutouts were a cost saving on later models may be wrong if the 137 had veneered cutouts. I was surprised to see the veneer there as I don't know of another radio where that trouble was taken. It must have been quite labour intensive to do. There again the whole process of manufacturing these pre-war radios must have been labour intensive. No wonder they were relatively expensive
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Old 31st Jul 2020, 2:53 pm   #14
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Default Re: McMichael 135s - a comparison.

Hi 137 as far as I know was 17 gns with an extra 2 gns for the stand.
Cheers.
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Old 31st Jul 2020, 6:40 pm   #15
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Default Re: McMichael 135s - a comparison.

For many years we had the original receipt for the 135 which my grandmother bought for my grandfather when he retired. I think it was 15 or possibly guineas with another 2 for the stand. Unfortunately it was lost in a clear out. It lasted until the early 70s with no repairs at all when my mother gave it to the bin men after I foolishly confessed to having had a shock off it.
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Old 1st Aug 2020, 10:56 am   #16
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Default Re: McMichael 135s - a comparison.

For several years I owned a 135, 137 and the rarer 138 (oblong flat dial with pre-tuned push buttons) but sadly they had to go when I moved house because I didn't have the space. They are lovely radios, but take up a vast amount of room. I've attached a Wireless World review of the 135 dated 31 May 1935, and an extract from a 1939 McMichael brochure (possibly Radiolympia) showing the 137 at 17 Gns for the AC model and 17 & 1/2 Gns AC/DC. The cabriole legged stand was 2 Gns extra. At least it looks like the valves were included in the price! The 138 was more expensive at 18 & 1/2 Gns and seems to have been AC only. Cheers, Jerry
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Old 1st Aug 2020, 11:14 am   #17
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Default Re: McMichael 135s - a comparison.

Thank you Jerry, they are very interesting. I once saw a similar set in a junk shop but it had long oval speaker cutouts. I think there may have been a just post war TV set with a similar cabinet.

I think I was mistaken in thinking that my 135 with the concave back corners was the later one. As has been mentioned before, the 137 and now the 138 are pictured with square corners whereas the 135 shown has the concave ones. My 365 radiogram also has square corners. Presumably the 135 with the square corners was produced just before the 137 came out and the cabinet modifications had already been made.
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Old 1st Aug 2020, 2:06 pm   #18
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Default Re: McMichael 135s - a comparison.

To get a quoted 5 watts from the AC2/Pen, what kind of voltage will be arriving at its control grid from the Detector?
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Old 2nd Aug 2020, 9:00 am   #19
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Default Re: McMichael 135s - a comparison.

Hi Edward, if you're looking at the advert for the 138 which boasts a 5W output, the valve line-up is different to the 135. I cannot find any service data for the 138; I must have repaired mine using test and replace. However, to the best of my recollection, there is an AC/HLDD AF pre-amp stage. The AF output was probably an AC2/Pen but might have been an AC5/Pen. That said McMichael's advertising dept was not shy of blowing its own trumpet - I have a framed advert for McMichael Radio that bears the slogan "Costs a little more, so much the better!" Cheers, Jerry
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Old 2nd Aug 2020, 9:51 am   #20
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Default Re: McMichael 135s - a comparison.

The 365 radiogram, which has the same chassis as the 13* series uses an AC/HLDD and AC2/Pen. The anode voltage of the AC2/pen is quoted as 285v. I think I may have seen a Wireless World review of it somewhere but cannot be sure.
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