Valve/tube car radio AM to FM conversion ideas?

I don't think adding a single IC is going to give you what you want... instead, I'd look at a complete FM receiver. Take a look at the Velleman FM receiver kit at

There is a link to the "manual" for the kit that shows the schematic. Considering that an FM radio needs a few tuned circuits, building your own might be a bit more than you want to tackle. There are a few gotchas in this approach... no frequency display is the main drawback. But since the tuning appears to be via a small pot, you could draw one and fix it to the dash. Just tap into the appropriate power, volume, tuning, etc. on the board and bring them out to the dash. You can buy a copy of this kit at

If you want to go very cheaply, look at the little receiver at

It looks very similar to a little receiver that I was given at a trade show a few years ago. Major problem with this unit is that there is no tuning... it has a scan button; it scans the FM band from low end to high end. Just locate the power connections, volume control and scan button, bring them out to the dash panel, and you're in business.

Hth,

--
Dave M
MasonDG44 at comcast dot net  (Just substitute the appropriate characters in the 
address)

Experience: What you get when you don\'t get what you want

If you want someone else to work on your radio you might check with Gary Tayman in rec.antiques.radio+phono he does these conversions on a regular basis, and is a frequent poster over there.

Also If you are in Canada, you might contact Larry Wood @woodradios.com I think he has gone into doing something similar as well.

In consumer radio restoration , replacing the innards of a tube radio with a bunch of IC's is kind of frowned upon, as most of us strive to restore the radios instead. What I am saying is that you do have a choice, if the car is stock , personally I wouldn't go this route unless I couldnt' fix the orrigional radio for some reason, but it is a personal choice. I have an old volvo with an AM radio that was a transistor set, and my choice was to plug a FM tuner into the antenna , which the radio recieves on AM at a set frequency. That way I still can have the stock radio in place and tuck the FM unit away . If the car is old enough to have tubes, it will also have a vibrator and solid state vibrators are available. Either Gary or Larry might be able to give you the option of restoring the set for you as well if that is what you want. any old radio will probably need to be re-capped and alligned to work right.

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I should have said retaining the original in working order but just adding in somewhere, the guts from one of those matchbox size fm radios. No display just 2 buttons on/off and channel step and an earpiece. Maybe requiring some buffering or something to drop it in the existing (mono of course) amplifier. Preferably no holes drilled through the front pannel.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

There's a UK company that specialises in such work -

The Vintage Wireless Company

0161 973 0438

Think they're a pretty small outfit and it's possible they will give some help to a fellow trader. ;-)

--
*It is easier to get older than it is to get wiser.

    Dave Plowman        dave@davenoise.co.uk           London SW
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Surely the real fun is to use the FM to AM converter Rx so that yiou can listen to the "old 'un". I use my AMT3000 Tx the same way at home. Feed it with a s/s FM tuner and listen on one of several refurbished AA5's and AC-only sets to "exercise" them - the converter tube, IF amp and det/AF and OP tube all a-pumpin' away! Cheers, Roger

You have just described the FM Module exactly! Just one fly in the soup -- these haven't been available for several years.

I do stereo conversions on these radios. Vintage Wireless in England (mentioned elsewhere in this thread) also does these, hopefully quicker and for less money than it would cost to ship it to me.

All of these products originated at a place called Antique Automobile Radio in Palm Harbor, Florida. Dan Schulz, the owner, began as simply a dealer who repaired old car radios. As replacement vibrators became scarce, he started making solid state replacements. Then, as customers were asking for FM, he designed an FM Module that would fit inside the radio. Eventually he designed a stereo PCB, and the popularity of these soared -- to the point where only two dealers in the entire world were still asking for FM Modules (me and one other). They were finally discontinued. Now Dan is making reproduction radios for certain cars -- radios that look exactly like the original, but are complete new radios with the AM/FM stereo technology.

The FM Module was a neat little device. It was a tiny PCB with an FM tuner built onto it. Connections were to the antenna (with a 6.8 uH choke for separation), to the grid of the converter tube (or to the LO coil for transistor sets), to +12 volt power, and to the top of the volume control -- and the wire going to the volume control is rerouted to the PCB.

Switching is done by turning the radio off and immediately back on. PCB's could be set up for FM first, or AM first. In AM mode, relay is off and the AM audio is connected to the top of the volume control. In FM mode, the relay is energized, and the FM output is fed to the volume control. FM tuning is performed with the radio's original tuning knob -- it uses the radio's LO frequency to tune FM.

This Module was actually quite a performer, and a very likeable product. The one and only "bug" of sorts was the fact that it could drift, and the amount of drift varied with the radio model. The radio's LO drift is usually not enough to notice, but when multiplied for the FM frequencies it could make a difference. Even so, it still was a nice product.

At one time, about a third of the radios sent to me wanted the FM Module installed. It was also handy for early Bendix, and early Delco AM/FM radios with awful FM front ends. If repair of these was difficult or impossible, I would simply disconnect the FM entirely and install an FM Module to the AM coil. The only thing customers ever noticed was that their radio performed better than ever in FM!

The day the FM Modules were discontinued, I discontinued offering service on car radios. I've since offered service again on radios, but not on AM/FM's.

--
Gary E. Tayman/Tayman Electrical
Collector Car Audio
http://www.taymanelectrical.com

Just curious, would it be possible for you to duplicate those modules yourself, or did they require that NLA FM IC?

-

----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

-----------------------------------------------

These modules did indeed use specialized IC's, which were part of their demise.

AAR had just introduced a new version of the Stereo PCB, which had a digital tuner. It worked fine on the bench but went crazy in the field, so Dan had to quickly redesign it. It so happens this "quick redesign" was by far the best version to date, and sales suddenly went through the roof. However during this time Dan was going through some family problems, and if that wasn't enough the IC's used in the FM Modules were discontinued. So suddenly the FM boards became unavailable.

Dan eventually managed to redesign a new FM board, and this was cool as it was the size of a postage stamp. But it also had a bug. I was given about three or four to experiment with; I think one actually made it to the field and worked (in a Mopar 802) but the others are still here. Dan eventually decided that, with sales of Stereo PCB's going wild, and with waning interest in the FM boards, he scrapped the project.

The remaining FM Modules went pretty much to experimenters, some of which installed them in home radios, and they worked. Someday when I have lotsa time I'll tinker with the ones I have to see what happens. Installation isn't hard, except it needs 12 volts DC for power, and the radio must have an oscillator (meaning I can't put one in my AK-60 -- darn).

--
Gary E. Tayman/Tayman Electrical
Collector Car Audio
http://www.taymanelectrical.com