1951 LD10 KKV 222

[Vulgalour]

Just another small update here. As you'll know from earlier in the thread, we had previously picked up a Dansette portable transistor radio with the intention to modernise it as a removable unit for the car. A stroke of luck on another forum recently netted a more appropriate unit in the form of a 1947 (probably) Ekco CR32 valve radio, a unit specifically designed for use in a car. The unit was free, and while it appears to be complete, is untested. I've found and reached out to another radio enthusiast who has restored one of these units and hopefully they can provide some insight for us.

I will provide some photographs, etc. of the Ekco once we've had chance to do some more research and investigate it properly. If it turns out it cannot be repaired, it's in cosmetically perfect condition for the rest of the Lanchester's interior and is large enough that any modern upgrade could be fitted inside it without compromising the aesthetics and retaining functionality. Hopefully, it will be able to be revived as that would be much more fun. For a glimpse of what a restored one of these units is like, here's someone else's short video:



Something to aim for.

[Brian-H]

Somewhat more practical than the one in this thread viewtopic.php?f=26&t=6013 as that CR32 uses a vibrator to get the HV, rather than, I'm assuming, a dc-dc dynamotor in a power pack that the other one has. However, they probably both require a large antenna as the power from the transmitters was much higher in those days. Note also that, looking at the circuit diagram in the blog, that CR32 seems to have 6 "TRF" channels (fixed tune, looks like 4 MW and 2 LW) rather than being continuous tuning (superhet receiver). Mind you there isn't much choice on MW and LW these days anyway.

[Vulgalour]

We're wondering if the Dansette can be used as a sort of relay so the Ekco can pick up a transmission from it. I'm sure there's something you can do where you have a separate unit as a sort of receiver-transmitter so that it can pick up what your older radio can't, and then your older radio plays it out on a preset. I have a recollection that one of my friends years ago did this so they could play mp3s or minidiscs without converting their head unit, unfortunately I didn't pay enough attention so I may have filled in the blanks and smudged it about with the fog of memory and it's not something you can really do.

[Brian-H]

The "transmitter" idea comes from a method of getting MP3 onto a head unit that has FM radio, where the head unit has no external input (they usually incorporated a tape player, some early CD players also had no external input). These MP3 players have an FM transmitter, and you tune in the head unit to its transmission - but they're FM and transmit in what's called Band II (IIRC 98 to 108 MHz) whereas you require AM transmission in either the MW or LW band.

To do the same sort of thing from the Dansette to the Ecko, assuming the latter works, you might find a kit (or a radio ham who'd make something for you) that can be connected, from the feed to the audio amp in the Dansette, out to a small transmitter, tuned to the right frequency that the Ecko can pick up.

The other way would be to ditch the RF stages in the Ecko (just pull out the valves, unless their heaters are connected in series, in which case they'd have to stay in) and then take the feed to the audio amp in the Dansette direct to the input of the audio amp of the Ecko. You'd just have to ensure that there was a capacitor at each end of the feed so that there'd never be a DC connection between the two units.

[Sydsmith]

The greatest challenge with old car radios is the very hefty battery consumption, adding even more battery drain by way of extra items will increase that consumption.

I would have thought it would be best to ditch the old valve set up and fit a modern radio module in the case, there are specialist who will do the job, at a price, it's not an easy job unless you have a modicum of electronic and fabricating ability. Syd

[Brian-H]

Have a look at the youtube video on that CR32 Syd, it's only a couple of minutes, and underneath the vid there's a link to the man's blog. Either in the video or in the blog, or both, he's converted it to run off a 6 Volt rechargeable motorcycle battery which fits in the case. He says that the largest current is the valve heaters which is about 4 Amps.

[Brian-H]

The MW band in Europe (which includes UK for this definition) is 531–1,602 kHz (or in MHz 0.53 to 1.6, or in metres 565 to 187).

For £18.39 you can get a 3 channel AM transmitter from a seller in Lichfield https://www.ebay.co.uk/itm/313309975816 - you can get the same thing for less, direct from China.

It has an audio input, runs off a 3.6 V battery, and the 3 channels are 1 MHz, 3 MHz and 5 MHz . So you'd have to use it on the 1 MHz channel (1,000 kHz or 299.8 metres) and then tune one of the Ecko channels to that fixed frequency.

So if that Ecko can be easily made to work, all you need is an MP3 player, plug it into that transmitter, and off you go. Note that if the transmitter is next to the Ecko, neither would require a full antenna, just a very short piece of wire. That way, the transmitter won't interfere with anyone else listening on 299.8 metres AM as you drive by.

[Vulgalour]

That, and info about the inner workings of the Ekco that I've had from other forums, is all very promising for this little project. It seems there's not a great deal that can go wrong inside the Ekco, they're a fairly robust unit, and knowing there is a way to get it to pick up a transmission that would allow it to function almost as originally intended certainly has appeal. While modernising the internals would definitely make for a more practical unit, it really would be nice to keep things original if possible, after all, the Lanchester is something of a special occasion car so the novelty and limitations of a valve radio adds to that, rather than being a hindrance, it's all part of the experience.

I do have the service manual and wiring diagrams, courtesy of Mickey Nold who was kind enough to forward them, and the instructions are clear enough that even I can understand what's inside this radio a bit better. Before going further, I'm going to have to get some new capacitors to replace the wax ones, possibly some new wire since some of the insulation is sort of spongey and brittle at the same time, and a desktop power source so I can introduce power gradually for testing, rather than just hooking the thing straight up to a car battery. Because the components are quite chunky, it's much easier for me to actually understand what I'm looking at and it will hopefully give me some confidence with electronics which will be particularly useful when we install the new wiring loom later this year. If it ever stops raining.

[Brian-H]

If you want a bench power supply these Farnell ones are good (I've got 3 similar to this) https://www.ebay.co.uk/itm/224387158513
But that one is already at £21.50 with 6 days left. As it's a 0-30V 0-5A linear PSU it might reach £50. They're fairly heavy so £9.50 postage is reasonable. If you get something like that, you can set the voltage very accurately, and also set the current limit (I use my ones for re-charging batteries - SLA/AGM, series connected NiMH, LiPo).

That Ecko uses 5 valves - ECH21, two EF22's, EBL21, EZ35. They're all 6.3 volt heaters (not series heaters then) so in 6V battery operation you can pull each one out without affecting the others. However in 12V battery operation you can't do that because they're connected in series and parallel (along with a 68 ohm resistor).

Without having looked at the service manual, I don't see how it's possible to introduce power gradually because the heaters require full voltage and current to work. In fact, the service manual is more likely to provide test voltages at points in the unit when it's fully on, and the use of specialist equipment to adjust the 'Q' of the RF/IF stages.

What you can do is remove all the valves and see if the vibrator works and gives you a high AC voltage ~300 volts - that can be checked by slowly winding up the current limit (if you have something similar to that Farnell) until the vibrator runs and the transformer gives the AC volts (you won't get DC with the EZ35 removed). If the unit was for 6V operation the next step would be to put in the EZ35 and see if you get 300V DC. Then stick the other valves in (one at time from EBL21 backwards if one prefers) and recheck the HT. But if the unit is for 12V operation, the valves are all or none.

The heater currents are - ECH21 = 0.2A, EF22 = 0.2A (so two require 0.4A), EBL21 = 0.8A, EZ35 = 0.6A
So in 6V operational mode the heaters would pull 2A and in 12V operational mode the 68 ohm resistor adds approx 0.1A to the current in the heater circuit.

Mickey Nold said it requires 4A so the remaining current (2A) comes from the vibrator/transformer to give the 300V.

btw looking at the circuit it is a superhet but with 5 fixed frequency selectors instead of variable frequency selection. It's a nice radio but AM reception is horrible these days, far worse than I remember when listening to pirate radio in the 60's or radio buxom-girl at night.

[Sydsmith]

If it any help when you get that far I may have some or all of those valves (new boxed) stashed away in my attic. Syd