This is the second of eight radios I bought as a job lot recently. Outwardly it looks not too bad. The case is in one piece but the two front knobs are broken. The mains / battery switch is there but does not feel right with the latching not positive at all. I can feel only two positions where I think there should be three. I pulled the chassis out of the case and it looks like a really interesting little radio. I started by measuring the power transformer. The resitances across the primary side looked OK to me with about 140 ohms on the first voltage tap (205v) increasing a little each time on the remaing two taps (235 and 250 volts). The worrying thing for me was there was no continuity between the common and any of the three voltage taps. The same thing happened across one of the secondary windings. 250 ohms across the winding and half that amount across each end and the centre tap but again no continuity. The other secondary had very little resistance maybe 2 ohms and it did have continuity. By the way I was measuring continuity with a digital multi meter with a buzzer sound indicating continuity.
Thinking that the transformer must be faulty I pulled the module out of the chassis and removed the transformer. After separating it from the rectifier tube and the other stuff (Carefully recording all the connections and taking a couple of pics for later reference). I hooked it up to power and did some voltage tests. To my surprise the thing seems to be working correctly after all.
With the primary hooked up to the 250V tap I got 290 volts across the larger of the two secondary windings and 145 volts each end to the centre tap of the same winding. The remaining winding gave 6.95 volts. These voltages seem correct as the cathode of the 6V4 rectifier tube expects 141 volts according to the tube data and I guess the other is the filament winding which 6.9 volts would be about right.
So my question is. Is it normal not to get continuity where I have been looking? Or is there indeed a problem with this transformer.? Any explanation that would help me understand this vexing problem would be much appreciated. Sorry if this is a dumb question but I am just starting on this journey.
Cheers
Ray

Continuity meters don't handle impedance, ie an inductive circuit.
Only pure resistance, and very low at that.
For general valve/tube servicing continuity testers best left for other low resistance circuits.
And will give false reports on anything inductive, ie transformers.
Your power transformer is OK.
Should have fired it up with a series globe(dim globe) whilst in circuit, initially.
Saving a lot of time.
JJ
Added comment, electronic continuity testers, like the ones used in smart multimeters don't like impedance, so give false info.
But the old style using a battery and a series globe tests DC continuity, provided the circuit being measured is of a very low resistance.
So, still be not useful for mains transformers.
Might give a result in the filament winding though.
JJ

Thanks JJ. You are right about causing a lot of extra work. But at least I have learned something along the way and I will take advantage of having this module stripped down to change three electrolytic caps while I have good access. Thanks for the info.

I hadn't heard of the 21-11, but as soon as I saw a picture I realised I have one or two of them. The plastic dial cover can disintegrate over time, but sometimes you can find one that is still perfectly good.

It uses 1 volt valves which means you can't see if they light up or not. With everything in series it only takes one small thing for the whole radio to just stop.

If you can get audio to work, but no stations, the 1R5 valve is suspect - they are not very reliable.

Yes. mine has no dial cover. And the plastic printed sheet with all the stations marked is torn in a couple of places as well. I will address these issues later. For now I have to dig myself out of the mess I created by removing the transformer module and stripping it down. I cut quite a few wires which will now have to be lengthened and re joined. The other thing that is making me nervous about this set is the mains connection. It appears to be just two round pins. I will have to figure out how to connect a three pin mains plug in it's place. I could use some help with that.

I've never seen a faulty power supply in one of those radios, although the electros can look worn out and possibly need replacing.

I've been lazy and simply wired in a 2-wire mains cord. I'm not sure if it's safe to earth the chassis on those - you'll have to check.

If it is an AC/DC set, look for a power transformer. If there is no transformer, you do not earth the chassis. Additionally, extra care must be taken when working on these sets. As there is no mains isolation, you have zero protection if your fingers go wandering.

Search for "working on AC/DC valve radios" for more information. Most of the search results are from Britain but the principles are the same.

This one is AC/ Battery with transformer. Therefore it is not a dreaded AC/DC type.

There is a voltage chart in AORSM's. As it is transformer, its chassis can be grounded. I note four electrolytics.

The mains is switched on the wafer switch, keep fingers away from that. Naturally since they destroyed Union Carbide, Bhopal: No batteries.

I would ensure the transformer is on the 250V tap.

Thanks for the help guys. I have re assembled the power supply module. I call it that because it is in its own chassis seperate from the other workings. Anyway it's back together and I am now thinking on how to get a three wire mains cable safely hooked up to the radio. After I get that done I have built a dim bulb unit so I will power it up with that and see what happens. Oh I will also move the mains to the 250 volt tap. It's currently on 235.

Seems my memory wasn't quite as good as I thought. I went looking for my 21-11, only to find it's actually a 11-11. It looks totally identical though. Plugged it in, and it works. It has the original correct mains cord, so nothing bodgy there.

The difference is that the 21-11 has an extra valve, a 1S5 as an audio preamp stage.

My radio is yellow. At one time I also had a red one, but it turned out to be a total wreck, and got scrapped years ago.

I powered up on dim bulb and started checking some voltages. Noticed that the filaments had way too much voltage on them. Around 18 volts I think. With the exception of one which had zero volts. It was the last valve in the train so I pulled the preceding valve and it was open circuit between the filament pins. Shoulda known it would be the 1R5. Robbbert is a genius. All the screen and plate voltages were way too high as well. Around 120v on all. Haven't thought about those too much yet but now I am wishing that I had checked the cathode voltage to the rectifier valve when I had good access. I reassembled the radio and put it aside for now as I don't have a spare 1R5 and a quick look on line indicated a replacement would be a pit pricey. Plenty for sale in the states but postage is a killer. I will wait for one to turn up closer to home.
My first defeat. Very deflating. Never mind. Onwards and upward. I delved into the big cardboard box and out came a little oblong maybe 15" by 5 by 5" with just one knob and a circular dial on the front. A badge with Titan in the lower left corner was the only identifying feature. For the life of me after searching and searching. I cannot find anything on this radio. The closest I can find is a H.G.P RM2L. It looks very similar and has the same valves except the 6AN7 is a 6AN7A in my set. I haven't been able to find a schematic so far. Radio Museum was the source of what info I could find. After tracing the remains of the mains cord I worked out active and neutral and connected a power cord. Bingo. The radio came to life. The tuning dial is broken at the boss that attaches to the tuning cap shaft but I was able to turn the cap and get a station. Works pretty well but a bit of hum. Not sure what to do with this one. I will see what I can find on repairing the tuning dial and if successful will press on. If not it's back to the box for another one.
Meanwhile life is getting complicated as I am cosumed at the moment. Each morning I am drawn to the shed and everything else is just noise. The boss is getting agitated as the grass grows ever longer and the yard is becoming untidy yet still the shed draws me in. This is getting serious. I may need help. Of course none of you have ever had these symptoms so I don't expect any sympathy. But if you can point me to a schematic or have any other helpful advice it would be most welcome.

If it helps, 1R5 is also known as DK91. Most battery sets made here will likely have a 1R5.

According to my equivalents book, it's also known as X17 but I doubt anyone could find one of those.

The "Titan" name sounds familiar, I suspect some of the other guys will know more.

1R5 military number is CV782.

Ray I have some 1R5s that I will never use.

My email is unhidden.

KG Harris Industries made Titan radios and TVs.
They also made for HG Palmer.

Thanks for the offer Ian. I will be in touch. As for the Titan brand. I did search all the KGH Titans listed on Radio Museum but none were a match for my set. Luckily the radio works so a schematic is not urgent at this stage. In fact I think I will put the Titan back in the box and get back to the 21-11 now that you have offered me a tube.