I was planning on gardening today, but it rained, so I worked on 2 more radios instead.

1. The Philips 172 that had previously been worked on, but had broken down in the burn-in period. The sound was weak to almost non-existent, with crackling noises every so often. After testing every other thing, found that the speaker (Rola C) had karked it. So it was replaced with a spare EMI (Made in Sydney) speaker. While I was there, I replaced the 2 components in the G2 power supply - the 68k resistor measured 132k, and the wax capacitor was leaky as a colander. This radio is a real cow to get back together, and only then did I find out that the slightly larger magnet of the new speaker fouled the power transformer - but not by much, I was still able to get the radio back together. So it's finally working.

2. Radiola B17 (6BE6, 6BA6, 6AV6, 6AQ5, 6X4). The dial indicator was missing. Someone had put this chassis into a home-made wooden cabinet which looks awful. Going by the number of stickers on it, this radio had done the rounds of resellers a few times. Once I got it open, I found the indicator had fallen off the dial cord and was lying out of sight. I reattached it, tested the radio which works. Looked underneath, saw the huge number of wax caps, and quickly put the radio back in its case. The radio is working, so perhaps I'll replace all that stuff at some other time - maybe. I had previously replaced the cap on the 6AQ5 grid, so at least it won't go up in smoke tomorrow.

I looked at the next 2 radios, a pair of Philips European push-button radios with no sound, and decided to leave them till next week.

Over the last month or 2, tested a whole bunch of plastic radios, and found that almost all of them are working, which was a great relief. There's probably only about a dozen or so radios left to test.

One thing that's even more obvious than I had realised, is the small range of valves used in Aussie radios. Despite hundreds or perhaps thousands of valve types in existence, we only used about 20 or so types.

Next installment...

The 2 Philips radios mentioned above, made in Holland. They are pretty much identical, slightly different arrangements with the ferrite rod, the antenna connections, and one has a PU connection and the other has a hole instead. Valves: EZ80, EL84, EBC81, EF89, ECH81, DM71. This is actually a good selection of valves, and in both cases I had already replaced the EF89 with high gain TV valves (6EH7 in one radio, 6EJ7 in the other). Also in both radios the EZ80 had been replaced by 6V4, and EBC81 replaced by 6BD7 (these make no difference, they are just equivalents).

First radio, model B3X16A/00K - no sound. I made a few measurements which indicated that something should be happening, but it was silent as the grave. In fact it was so silent that I suspected the loudspeaker, and this proved to be so. It was open circuit, measurements of the connecting wires, the voice coil and even a short wire wire connecting the earth to the frame showed them all to be open. No doubt the green corrosion played a part. I found a replacement, and the radio was then working fine.

2nd radio, model BET336A, this one is for the Arab market, all the indications are in Arabic. The dial cord was jammed. Application of oil in the right places sorted that out. The tuning capacitor uses a gear train, because the dial drum is only about 2cm wide. This was seized up. The radio worked well after that.

The only thing wrong with these radios is the DM71 tuning indicator doesn't do much, in fact that indicator is pretty much useless in every radio I've ever seen it in. I suspect it was just there as a sales feature rather than being useful.

Last radio for the night was a HMV B13C with no knobs and a cracked plastic yellow case. The speaker transformer had been replaced at some time and had come loose, shorting out things at random. I soldered it back in place. When the radio was tuned to 2UE the dial said 2CH, so I just moved the pointer along to where it belonged. Radio then worked well.

I've now caught up with the repair queue. There's still about 10 radios to test, and I know at least 2 are faulty. So I'll report on them when the time comes.

I've now caught up with the repair queue.

You've really gone hard at that pile.

BTW: where did you obtain all of these non-working radios, and over what period?

The majority of radios were obtained at the flea market on Camden Valley Way at Prestons (outer SW Sydney). The place is easily recognised as it has a big Taj Mahal entrance. It closed a few years ago to make way for yet more housing, but the last time I drove past it was still there. No idea if it operates still. The time period was late 1990's to about 2010, I stopped when radios started becoming harder to find and more expensive. Back then they were quite cheap and could be mostly had for 10 or 20 dollars. You could get boxes of valves for next to nothing too.

After that, I visited various antique shops, buying up whatever they had. I stopped in about 2018 (I think) because I felt I had enough, and again, harder to find good ones at cheap prices.

My original radio, the 10-valve one, was given to me by a teacher when I attended high school, in 1973 (I think). It was my first big radio, I had only played with crystal radio kits before that. Me and a friend raided the council tip (you could do that then), and also a disposals store at Tempe and the salvation army place there too. The salvation army place had a whole yard full of old consoles and whatnot that they couldn't sell. It would have made today's collectors swoon with delight.

There were many other places in the inner-city suburbs that were run by old men or families, that had masses of valve stuff, although I never visited them (I didn't have a car back then). In the 70s and 80s you could buy the things for a dollar or two, but I never had the time or space for it, nor a means of transporting them.

Today though, apart from deceased estates and oldies wanting to clear out rat-infested collections, there's relatively not much left, sad to say. Council kerb-side collections are entirely useless now too, when they used to provide plenty of old radios and TVs.

The 'good old days' of collecting are pretty much over.

I see what looks like a repeat?

There is around a 99.99% chance that any old type Wax paper cap is leaking. If you use an insulation tester on wax paper caps working volts or, test volts (out of circuit). If its under 50Meg its a dud & useless for decoupling. If its under 200Meg it useless for coupling. If its Wax paper & in a radio: That's a wrong part replace it.

Some seem to forget cathode bypass & bypass caps on back bias. They loose polarity just the same as filters. If the cathode resistor is open, they will be punched through.

I commercially fix. There is only one standard. If its not good enough to send to a customer, its not good enough for any refurbishment.

Marc

Please stop it with the random comments. I said before I don't have customers, and I do what I want - not what you want.

Robbbert I enjoy reading your escapades in fixing those radios.

Some of them are the same models that I have had a go at and I can visualise what chassis you are working on.
The whole process is a journey of discovery and despite what it may look like I have no formal "radio" training.
So every thing I know has been gleaned through pulling things apart and nutting out how it works and why it does not.

About 20 years ago I had no idea how a superhet radio worked.
Now I have a bit of a glimmer, but more importantly, I understand how much I do not know.
There are levels and layers in everything and realising where you are at and how much further you can go is the important thing.

Being able to write is another tangent.
To clearly explain what you are doing and how you do it, is an art.
I have a bit of a grasp and seem to write stuff that people like to read and editors like to print.

Keep going on the journey mate, you cannot know everything but you are on the road to finding out a lot.
Look forward to your next post.

Fred.

Hi Robbbert,

Mmmmm ... sounds like you need a new challenge ... do you still have your original radio ...10 valves ....??

Sounds like a Comms Receiver ... with an RF Amp front-end, separate Oscillator, extra IF stage, separate BFO and /or AGC, and maybe a Q-Multiplier .... ????

The 'good old days' of collecting are pretty much over.

As regards 'dollar bargain' collecting, that's for sure.

And on the other side of the coin, the market seems to be saturated with old collectors dying off, or wanting to be rid of their hoards as they downsize their residences, and comparatively few new collectors wanting to buy in quantity.

As I think I've mentioned here before, the President of the Sydney NSW HRSA group has bemoaned the low prices being fetched at auction for radios in very good condition in recent times. He even appealed for members to be prepared to pay more. (Good luck with that I thought.)

It's really becoming a situation of high supply and low demand.

That said, certain radios considered 'must-haves' by the cognoscenti will probably continue to be fought over.

GTC, I wonder what those 'must-haves' are? I don't have any cathedral-style or empire-state-style or mickey-mouse radios, assuming they are must-haves.

Tinkera123, I still have that radio, but it's just a normal AM MW/SW/Gram from some long-forgotten console, nothing special, just more valves than usual. At some time I rewired the audio section to be a ultra-linear type, and it sounds good and makes a lot of volume. But at its core, it's just a radio.

Fred Lever, I am self-taught too, it all comes slowly with experience, but as you've seen there's lots I don't know, and these days I couldn't be bothered with the fiddly time-consuming stuff. There's more repairs coming next week, since I found 3 more faulty radios today.

I wonder what those 'must-haves' are?

So-called Empire State would probably be top of the list (I consider the design ugly and am not the slightest bit interested in it.)

Other categories would be coloured radios generally (i.e. other than brown) and 'series' radios where people try to collect the entire model range of the 'series'.

The only must-haves in my collection are those sets that I grew up with and, apart from a 1920s console gram (no room for it anyway), and a 1960s HMV radiogram (not that fussed about it), I now have them all and in working condition, so I'm no longer a collector as such.

Other categories would be coloured radios generally (i.e. other than brown)

Well, I do have quite a lot of coloured radios, assuming that plastic ones are included in that category. But as to the value or desirability of any particular one, I wouldn't have the slightest idea.

I like my radios based on performance and practicality. Like GTC the empire states never really excited me. A lacklustre performer which doesnt look so bad but not a eye catcher. Give me my Leningrad Kotsiski (11 valver ) any day or my old PYE that I just refurbished that picks up The Philippines like it was next door or the Myriad of 80 plus radios I have strewn around the house.
Robbert keep up the repairs and commentary as its interesting!

Not very exciting for today's report, sad to say.

1. Mullard MAS1001A, with half the back cardboard missing. Valves: 6AN7, 6N8, 6M5, 6X5GT. Although it had lots of volume, it was a bit muffled. When I got it open the wiring around the volume control made no sense, so I downloaded the schematic. Once I looked at it, I realised this radio uses reflexing, and while it saves a valve, there's always a compromise. So in fact the radio was working just fine.

2. Stromberg-Carlson 4A19. Valves: 6A8G, 6AR7GT, KT61, 6X5GT. Very low volume. The radio side seemed to be ok, but barely audible. Again, the volume control made no sense, so I downloaded a blurry diagram. After examining this, I realised what an abomination this radio is. Stromberg-Carlson should have been ashamed to have ever sold it. There's only 1 IF transformer - the first IF. There's no AGC. The volume control is attached to the cathodes of the first 2 valves, instead of actually varying the volume. Since DC is passing through the control, it makes noise when turned. Anything less than 80% volume is totally silent. The HT is not even 200v, so it will never work well. What a disaster. Considering it was made in 1949, they could have done much better.

So, the KT61 wasn't there - it had been replaced by a EL33, which being gigantic, took up most of the space inside. I don't have a KT61, so I decided to replace the EL33 with a 6V6GT and alter the bias to suit. The 100 ohm cathode resistor became 250 ohm, and the open-circuit 10μF electro was replaced. For some reason there was another electro from the volume control to ground, not in the schematic, and it was in parallel with another cap, so I removed this electro. As expected there was no difference. The use of the 6V6 gave another 11 volts of HT, but unfortunately none of that did much for the volume, so I guess it was just designed that way. Not very efficient - at least 30 watts used to make about 1/8th watt of audio. At least I didn't make it worse. I wonder if anyone else has one of these, and is it any good?

3. Unbranded radio. Valves: 6SA7GT, VR91, 6BV7, 6X4. When it worked, it worked well - but it cut out now and then. There's no power switch, so the power cord has a hexagon-shaped bakelite slide switch. This made noise when it was touched, so I removed it and wired the power cord directly into the radio. The actual reason for cutting out was found a bit later, the aerial cable was dry-jointed where it joined a short internal cable just next to the tuning capacitor. And when I thought I was finished, suddenly there was no lights and the power transformer got very hot. I found that the socket for the dial light had developed a short. I had an exact replacement, so it didn't take long to fix.

4. Astor, unknown model. Valves: 6AN7, unknown octal, unknown octal, 6F6G, 5Y3GT. The unknowns were in goat shields and I didn't feel like pulling them apart. The case is used in many Astor models that look identical from the outside. There a knob on each side and 2 knobs on the front. You have to unscrew 2 plastic retainers and remove the dial before you can get the chassis out. On most of these radios it's all frozen up and everything breaks while trying to open it. Also, some of them had cheap spring-shaped lamp holders which have fused with the lamps (some kind of metal migration) over the years and they cannot be separated. On my radio the physical side is good, but I had to scrap 2 others which had wrecked themselves.

Anyway, the issue (I thought) was although it worked, the 6F6G's grid seemed to be red. I found that the grid resistor had risen from 500K to 650K, so it was replaced. This calmed things down, but I still didn't think much of the sound quality. I decided to replace the 6F6G (Made by Acturus) with a nice-looking Philips Miniwatt one. This not only fixed the imperfect sound, but at least doubled the volume too.

So that's all for tonight. 2 fixes, one already working, and one not sure about.

Then I found a Philips which is very insensitive. If I put my hand near the tuning capacitor it gets quite loud, but via the antenna it's useless. I may look at it tomorrow, or perhaps next week.

Hi Robbbert,

What is a 'goat shield' ... in the Astor ... no: 4 radio fix??

Re no: 2 ... Stromberg-Carlson ... could the low volume be resulting from some mis-alignment in the IF due to component ageing etc??