Sh!te Car Radio

[LC Torana]

After 20-odd years' service, the radio/cassette in my P6B wouldn't play tapes properly.  No doubt a worn and loose drive belt, so let's open 'er up and measure the belt, order a new one and repair it.  The dial lamp went years ago, so high time for a service anyway.

 

But you know what?  I'm sick of working on modern electronic chod, so I'm afraid I just swept the pieces up and binned the whole thing.

 

Let's just buy a new one.  Something nice looking, not too dear, anything modern will sound good, so let's look at the well-known car radio sellers websites...

 

Where are the car radios?  What the fü¢# is a "head unit"?  And what sort of person wants a garish LED light show on the dashboard?

 

MP3, Bluetooth, phone connectivity - oh fü¢# off.  I want something for grown-ups.

 

Time for some genuine sh!te audio.  Let's scan the secondhand market.

 

Another AM/FM set with cassette player?  Not sh!te enough.  Those that have survived will be quality units at scene-tax prices.

 

AM/FM with CD?  No, not sh!te enough.

 

How about a classic AM/FM radio?  Ought to be period-authentic for 1976?  Hmm, still not sh!te enough.

 

So to be truly sh!te, we need an AM, MW-only set (there is no LW in Australia).

 

OK, so a classic AM radio with 5 mechanical preset pushbutton tuning?

 

No, those were often of genuine quality.  Great selectivity and sensitivity, and enough gain and AVC to drive under electrified railway viaducts without signal strength changing.  Still not sh!te enough.

 

I'm looking for real sh!te that nobody wants.

 

So what about a classic valve radio?  Loctal valves, a vibrator and an 0Z4?  That would be fun, but there's no room in the car for one of those - the aircon takes up the room I would need for that.

 

Ahh, now I've got it.  The most sh!te car radio ever made is within my grasp.  In fact, I have a broken one in the back of the shed cupboard.

 

The first practical and successful car radios, like the classic Radiomobile 100, used full-size valves and a vibrator power supply to give the 200 or more volts HT the valves needed.

 

In the 1950s, miniature valves arrived and radios could get smaller.  Some of these later sets are amongst the best car radios money could buy.

 

In the early 1960s, the all-transistor radio was perfected, and before cassette and 8-track arrived, all the money on car audio was poured into AM radio quality, by which I mean 6 things:

Sensitivity

Selectivity

RF/IF Gain

AVC

Power Output = dynamic range

Audio quality.

Radios from this era represent the absolute pinnacle of AM car radio development.

 

So it's clear I'm not looking for one of those.

 

The absolute nadir of car radio was at the end of the valve era / the very dawn of the transistor era.  1959-62.

 

The age of the "hybrid" set - half valve, half-transistor.  These were truly sh!te.

 

So naturally, that's what I'm doing up for the P6B.  Here's the circuit diagram of mine:

If anyone's interested, I can post what I had to do to get it going.

 

It's physically a standard 1U DIN size or thereabouts, so fitted in the dash.

It wants to work into a 3.5 ohm load, so I've got it hooked up to the driver's door speaker only - how sh!te is that?  With single-ended class A output, load is fairly critical.  An auto-transformer to divert a little sound into the other speaker is on my shopping list, when funds permit.

 

Rotary tuning on the left, no presets, off/volume on the right with tone control concentric.

 

When you turn it on, the transistors are awake immediately, but silence reigns until the valves warm up and the sound then comes on with a thump.

It then sounds AWFUL for about a minute until the valve heaters are fully warm, then the sound is rich, smooth and pleasant.

 

It suffers a little frequency drift, so you do need to re-tune a bit now and again.

 

No voltage regulation, so it's quiet at traffic lights and louder on the move.

 

AVC and gain are a bit marginal, so viaducts and power lines upset it.

 

All in all, a delightfully perfect piece of rolled-gold sh!te that pleases me so much, I now listen to the radio in the car more than I have for years.

 

Here's a pic of the faceplate:

[purplebargeken]

That looks cool!

[UltraWomble]

It has a lovely glow that will keep you warm at night

[Andrew353w]

Beautiful! I love those old car radios! There's a certain warmth they exude that modern clinical digital equipment just doesn't have! Even better if it has a short-wave range. Decent large speakers that don't shake themselves to bits when the volume's turned up a bit and give the full range of sound with a rich tone-speakers that would sound good with "Winston Churchill speaking to the nation" through them.

[jonny69]

Wow, that's way cooler looking than I was expecting!

 

I've never found a good-looking 1960s radio before because all the European stuff was later black plastic knobs and push buttons and always looks out of place in a 1960s car. I don't even know if we had sets like that over here, I've never seen anything like it.

 

Looking at the circuit diagram, it's a transistor output stage despite going through an output transformer so the impedance of the speakers is not critical. It seems to suggest that the output impedance of the transistor is 20 Ohms and the transformer changes this to 3.5 Ohms, probably because those early transistors could sling out some voltage but not much current. You could put an 8 Ohm speaker on there with no problems but it would just have a reduced output. It won't hurt it like it will with a valve output stage. The key thing is to not go too much below 3.5 Ohms or you'll overload it, so stick to around 4 and you'll be fine. Interesting circuit though - all those valves operate at low voltage and there's no HT like you'd normally find in a valve circuit.

[STUNO]

Wow, that's way cooler looking than I was expecting!

 the transformer changes this to 3.5 Ohms, probably because those early transistors could sling out some voltage but not much current. You could put an 8 Ohm speaker on there with no problems

The key thing is to not go too much below 3.5 Ohms or you'll overload it, so stick to around 4 and you'll be fine. Interesting circuit though.

 

I understand about f**k all of that. Does that mean that two 3.5 oohm speakers are ok? Or just one 8 oohm ?

[LC Torana]

The overall load must be close as possible to 3.5 ohms.  Much less and the transistor will be overloaded, much more and distortion becomes unpleasant.

 

One 4 ohm speaker is close enough, or two 8 ohm speakers in parallel would also work.

 

My speakers are 4 ohms, so I'm using just the one.

[lovejoy]

I have just turned my microwave on, to listen to the 1-o-clock news.....

 

as you do....     Seriously, what an illuminating thread, I too  ADORE old car radios

 

that just have two rotary controls,  whatever happened ??

 

you can use them without having to take your eyes off the road, or if you have 5 thumbs

 

on each hand  -  that Golden Holden Radio looks bloody brilliant, specially with all the

 

extra SW bands to boot.   Nice thread, mate, even if it is upside-down 

[Station]

I don't collect or horde anything, but I have a load of old radios, but not as nice looking as that.

I bet it'd be nice having that on with some auld scrote on BBC Radio 4 grimacing about something mundane while you scoot down an empty M6 motorway at 2am in the morning.

[LC Torana]

...just have two rotary controls...

This one has three - the right hand knob is split - a tone control on the outer ring and off/volume on the inner one.

 

...with all the extra SW bands to boot...

Nope - no SW, just the one MW AM broadcast band. Strictly 540-1600kHz only.

[LC Torana]

I don't collect or horde anything, but I have a load of old radios, but not as nice looking as that.

I bet it'd be nice having that on with some auld scrote on BBC Radio 4 grimacing about something mundane while you scoot down an empty M6 motorway at 2am in the morning.

'Scuse my ignorance, but don'tcha need LW to hear Radio 4?

[saucedoctor]

Nope. 720 MW.

[mercrocker]

Fantastic radio....All it needs now are the Holden letters altered to read T A L A G O!

[Richard]

Is Holden a make of radio or was it originally fitted to a Holden car?

[jonny69]

I've come back in here because I want one in mine. I think it's time to set up some watch lists on eBay.

[LC Torana]

Is Holden a make of radio or was it originally fitted to a Holden car?

The latter.   I'm claiming bonus sh!te points for this, because you know those awful car radios people can't wait to get rid of, just to get something decent instead?  I've got one of those.  A cheap unbranded OEM radio that would have been fitted to an FB or EK Holden.

 

That said, I can clue you in on the manufacturer.  You see that illuminated red dot above the right-hand knobs?  That is the identifier for a car radio made by the mighty Radio Corporation of South Melbourne - maker of the brands Astor, Eclipse, Peter Pan, Monarch, Air Chief, EIL and Diamond Dot.

 

The CJR - this one, is made by this mob.

[LC Torana]

And just to clear up a misconception for British readers. What to your eyes might look like multiple bands isn't.

 

Australian-made radios made after about 1935 always had station callsigns on the dial, even if the actual frequency scale is absent.

 

This car radio is no exception. Australian AM radio callsigns are 3-digit codes, with the state identifier as the first digit, then 2 letters.

So at the right-hand end of the dial, we have stations 4SO, 2AN, 2LG, 5MG, 3WL and 3NE.

 

(Distances in Australia are so vast we can have two stations on the same frequency without interference, even on a clear night.)

[LC Torana]

I've come back in here because I want one in mine. I think it's time to set up some watch lists on eBay.

 

A similar* one has come up on eBay Australia - for a price, mind you.  Can't tell if hybrid or transistor; not enough photos.  At least it is complete with all knobs, faceplate, dial and jewel.

 

Perhaps the seller will offer a discount if you can name the tartan.

[LC Torana]

Something cheaper, perhaps?

[jonny69]

^ That is cute.

[LC Torana]

Been driving around in my P6B, with ye olde sh!te radio that's 15 years older than the car, playing classic rock.

 

Oh yes, one of the Melbourne AM stations has switched to classic rock format - the loud stuff.  That probably belongs in the grin thread, but this is my tiny corner of Autoshite.

 

Led Zeppelin, The Doors, Rolling Stones, Deep Purple.  Can't wait to blare this stuff out of my 1949 P3 with it's original Radiomobile 100.  When I get them both on the road, that is.

 

 

 

Edit:  I cannot even remember the last time I heard the Sweet's Ballroom Blitz on MW radio.