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Old 8th Jan 2017, 5:57 pm   #1
stevehertz
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Default Empress 7 Solid State radio

As a teenager (or maybe even earlier) I got bought an Empress 7 Solid State radio. We're talking mid to late 60s. It's a lovely dinky little set and like most people I used to listen to Radio Luxembourg on it beneath the sheets at bedtime. I recall that as I became interested in electronics I tried to tweak the slugs in the back of the set for better reception. Big mistake!

Fast forward to now and spurred on by the Benkson thread I dug it out and put a new battery in. It works, but it is very quiet, whisper quiet with your ear almost against it. Obviously such a small set never had much volume but I can remember being able to distort the small speaker in it with the volume up full. So, clearly there's problems. I'd like to get it working to original performance if possible. Clearly I didn't do it any good tweaking those three inductor slugs and the two tuning cap trimmers also. With nothing to loose I have tried tweaking all of them while set to a station to at least peak what I have got, though not a lot gained I'm afraid.

Any ideas? How can I go about resetting those slugs and trimmers? Incidentally the tuning dial is marked 5 to 16 (?) and obviously there is no slow motion, making it very difficult to tune in. Otherwise there's three Elcap caps in there that I haven't checked yet. I have cleaned the headphones/speaker switch. Are there any stock faults or issues re these 60s Japanese pocket sets?
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Old 8th Jan 2017, 6:16 pm   #2
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Default Re: Empress 7 Solid State radio

Many of the brand names used for these seem to have been interchangeable - I'm pretty sure the case moulding at least on your set here, down to the elliptical escutcheon for the tuning window, is exactly the same as that of a red Binatone I bought in about 1969. The tuning dial markings were pretty much standard, 5 to 16 signifying 500 to 1600 kHz, though back then most of us still thought mainly in wavelengths.

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Old 8th Jan 2017, 6:24 pm   #3
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Default Re: Empress 7 Solid State radio

Best way to align the slugs and trimmers etc is with a signal generator, IF's first, as a guess I would say the IF is somewhere around 455kHz, black is probably the last IF/Det, yellow the 1st IF, red the Osc, I'd change the electrolytics as well then take it from there.

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Old 8th Jan 2017, 6:38 pm   #4
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Default Re: Empress 7 Solid State radio

Tuning dial 5 to 16 will be 0.5 - 1.6 MHz.

Tweaking..... a sig gen will help but you can get somewhere without.

Set the trimmers to mid travel

Using a known setup radio, set that to 970kHz and set the Empress to 5. Tweak the Empress oscillator core until you find its LO on the test receiver. Then set the Empress to 6.93 , check its LO is now at 1163 on the test receiver, Twiddle the Empress IF cores and see if you can peak up on Radio 5 live (693kHz from Droitwich).

If this is successful, you're getting somewhere. Now find a signal near 16 on the Empress and peak it up using the oscillator and aerial trimmers.

This should get you working- if the IF for the Empress is 470kHz!

Have fun.
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Old 8th Jan 2017, 7:23 pm   #5
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Default Re: Empress 7 Solid State radio

Excellent, thanks guys. I'll give it a go and report back. I think I'll change those three caps in any case.
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Old 8th Jan 2017, 9:17 pm   #6
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Default Re: Empress 7 Solid State radio

Maybe it would be wiser to deal with the alignment and get it as good as you can. Then deal with the capacitors. You can always have another go later.
Has that radio been somewhere damp, or maybe in strong sunlight? The plastic has changed colour to that mucky green, which appears to be due to light. The inside of the case shows the original blue.
Maybe a chemical change in cheap plastic brought about by where it was kept. It has been seen as due to plastic protective covers in some cases.

To a collector, maybe not worth much if they were churned out in vast quantities as well as the condition. BUT this radio is a reminder of a part of your life, listening to R. Luxembourg fighting the 'atmospherics'. Was this around the time of the pirates or after the Marine Offences Bill when Radio 1 had arrived?
Luxembourg was probably the best source of pop music given their massive transmitters & their schedule was possibly much more reliable.

I can imagine why you would have wanted to make the radio sound more powerful when you were straining to hear a signal that kept fading in & out when your favourite band's latest hit was being played. Thankfully it is something you can put right.
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Old 9th Jan 2017, 5:46 am   #7
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Default Re: Empress 7 Solid State radio

Thanks Neil. Indeed the value of this little set is very little I would imagine, but it's part of my past. It has always been kept in a spare room, so no extremes of temperature, humidity or light really, the plastic has just changed colour with age and what small amount of light has got at it.
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Old 9th Jan 2017, 7:41 am   #8
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Default Re: Empress 7 Solid State radio

You are very lucky to still have that Empress 7. I would suppose that these radios were regarded as being disposable technology even then. They do sound pretty bad unless volume is kept low. Listening under the sheets was probably the best option. I never liked those earphones much. A r-r tape deck was robbed of it's Fane speaker. This was long before I ever had a record player.
listening to the likes of Slade, Mud & the Bay City Rollers. I was a child in the 70's. The radio I started with was one of those generic pocket radios that resembles a soap bar on account of the rounded corners. I thought that Fane speaker was hi-fi!
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Old 9th Jan 2017, 10:00 am   #9
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Default Re: Empress 7 Solid State radio

The Empire made set of my youth was a Perdio Popsy 2

The original has long since gone to meet its maker, I got as a birthday present when I was about 11 possibly 12.

It lived in the kitchen window for a lot of its life after the demise of the Regentone DW2 and fell in the washing up bowl many times.

These Empire sets were at the beginning of the end of the British domestic Radio and TV industry and the beginning of disposable electronics.

I bought a couple of examples just to remind myself how bad they were but at the same time how liberating, they were pocket technology affordable for teens.

Cheers

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Old 9th Jan 2017, 11:36 am   #10
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Default Re: Empress 7 Solid State radio

How true Mike. The build quality is shocking in many ways, they look like knocked together prototypes; poor fit of mechanical components, poor PCB, terrible blobby soldering, cheap components, etc etc. It's no wonder that the (once) great British R&TV industry laughed at them. But they didn't laugh just a few short years later when the sets improved and Japanese imports began to take huge market shares, eventually leading to the demise of the R&TV industry in the UK. They misread their customers, thinking that the old adage of 'people want high quality items' was still in vogue. They were so wrong. It was the swinging 60s, we had the Beatles, and fashion reigned over out and out quality. Those teenagers wanted a 'transistor' that they could carry around both in and out of the home, take it to work etc. And although they may be considered tacky looking to some, there's no doubt that the modern (albeit plastic) appearance of Japanese transistor sets appealed to that young market. In fact, even my parents, very conservative (lower 'c') as they were bought a 'transistor' as a replacement for our ageing table valve set. I think a lot of people probably didn't even notice the lack of sound quality - basically a total lack of bass. Oh hum..
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Old 9th Jan 2017, 12:24 pm   #11
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Default Re: Empress 7 Solid State radio

Lawrence, Herald, amalgamating the suggestions you gave me, this is where I'm at.

I set the Empress tuning dial to 5, other radio to 970Kz, and successfully adjusted the red slug to null the 'birdies'. If I then set the Empress to 6.93 , and check that its LO is now at 1163 on the test receiver (sound of birdies), it isn't, it's about 1070?

I can pick up R5L very faint when the Empress is set to about 8.

Update! I have managed to relocate R5L where it should be at 6.93 by adjusting the tuning cap trimmers and chasing it back into place. I have also tried tweaking/peaking the yellow and black slugs with some mild success (listening to R5L), but overall although the stations now appear to be in the right places, the volume is still pitifully low. Do I need to re-adjust the red core at all? Maybe the lack of volume is due to other, non-tuning related issues now? Help!
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Old 9th Jan 2017, 12:30 pm   #12
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Default Re: Empress 7 Solid State radio

Use a signal generator as suggested if you have one, my guess is 455kHz IF, but that's just a guess.

Just 5 on the dial seems a bit two low to me, that would suggest a tuning ratio of at least 3:1, normally its 3:1, is it just 5 on the dial or is it 53?

EDIT: It's bad practice trying to do Osc alignment unless you know that the IFT's are correctly aligned to their design frequency.

Lawrence.
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Old 9th Jan 2017, 12:42 pm   #13
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Default Re: Empress 7 Solid State radio

Thanks Lawrence, I edited my last post at the same time that you replied - does that change what you are saying?
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Old 9th Jan 2017, 1:01 pm   #14
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Default Re: Empress 7 Solid State radio

As far as alignment goes we know that all the cores/trimmers were tweaked years ago, proper alignment relies on proper IF alignment first, order of alignment is normally in this order:

IF>>Osc slug (low end of the band)>>Osc trimmer (high end of the band)>>RF coil on ferrite rod (low end of the band)>>RF trimmer (high end of the band) then re-check the Osc adjustments and RF adjustments.

The low output might be due to the electrolytics.

As said, signal generator is the best way if you have one, if not the IF's can be aligned without but it can a bit of an art.

Lawrence.
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Old 9th Jan 2017, 2:35 pm   #15
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Default Re: Empress 7 Solid State radio

Thanks Lawrence. Excuse me being slow (might be age, but probably born that way), I need some clarification on that procedure please. I'm the sort of person who needs step by step instructions unfortunately..

When you say "low end of the band" I presume you mean low frequency end?

Please could you reference 'colours' (of relevent slugs) to the instructions you give above.

Also you refer to adjusting the RF coil on the ferrite rod. Do I just move it along the ferrite bar? TBH I don't think I can do anything with it, it's all taped up.


Thanks!
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Old 9th Jan 2017, 3:08 pm   #16
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Default Re: Empress 7 Solid State radio

"When you say "low end of the band" I presume you mean low frequency end?"

Yes, that's correct.


"Please could you reference 'colours' (of relevent slugs) to the instructions you give above."

So far as I know the black and yellow slugs should be the IF transformers and the red slug should be the Osc coil, the Osc coil is adjusted at the low frequency end of the band.

"Also you refer to adjusting the RF coil on the ferrite rod. Do I just move it along the ferrite bar? TBH I don't think I can do anything with it, it's all taped up."

Yes, normally the coil can be moved either way along the ferrite rod but the coil is usually sealed to the rod and the seal would have to be broken, if the seal looks unbroken and original then normally I would leave the coil in that position.

The trimmers are on the rear of the tuning gang, two of them with the slotted heads, one of them is for adjusting the Osc at the high frequency end of the band, the other is for adjusting the RF at the high frequency end of the band.

Once the IF's and Osc are set correctly then sliding the RF coil for maximum noise at the low frequency end of the band would normally suffice, and ditto for adjusting the RF trimmer at the high frequency end of the band.

The RF Coil and trimmer adjustments are interactive, same goes for the Osc slug and trimmer adjustments so the usual way is to do the initial settings then re-tweak as required until there's no further improvement.

So to re-cap:

Osc slug = low frequency end, Osc trimmer = high frequency end.

RF coil = low frequency end, RF trimmer = high frequency end.

Lawrence.
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Old 9th Jan 2017, 4:53 pm   #17
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Default Re: Empress 7 Solid State radio

Thanks Lawrence. I've just changed those three electrolytics and the volume has come up to what I recall it was nearly 50 years ago. Well, on R5L it is although I'm not finding too many other stations at a decent volume. So we're clearly making headway, I'll have to have another go at realignment now.

BTW, the caps were well out of spec. The 200uF one, a lead fell off as I removed it, so not sure if it was working at all. The other two were - strangely - over stated value (30uF and 5uF) by several magnitude and showed a few ohms ESR. One of them is standing too high for the cabinet back to be put in place but that's not a problem until I get a smaller replacement, I just used what I had for now.

Oh, re the two trimmers on the back of the tuning cap, (as you say, one is for Osc, the other for RF) presumably I just tweak them both for maximum output when tuned to a station at the high frequency end? I don't know which one is which?
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Old 9th Jan 2017, 5:49 pm   #18
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Default Re: Empress 7 Solid State radio

Capacitance meters which work by timing only the charging phase (which seems to be most of them .....) will read "high" with leaky capacitors (since the leakage causes it to take longer to charge).
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Old 9th Jan 2017, 6:06 pm   #19
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Default Re: Empress 7 Solid State radio

"Oh, re the two trimmers on the back of the tuning cap, (as you say, one is for Osc, the other for RF) presumably I just tweak them both for maximum output when tuned to a station at the high frequency end? I don't know which one is which?"

The Osc trimmer will shift the tuning point at the high frequency end of the band, the RF trimmer the signal or noise strength, once you've identified which is which you could put a dab of red paint next to the Osc trimmer as a permanent future reference, eg: red trimmer, red slug = Osc.

Lawrence.
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Old 9th Jan 2017, 7:05 pm   #20
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Default Re: Empress 7 Solid State radio

All of this hangs on some idea of what the IF should be. Somewhere in the 455-470 kHz region almost certainly, but if you pick the wrong value, the tracking for the ae and osc circuits will never be quite right (though how much that matters in reality is uncertain). Maybe settle for 462.5kHz.......

If it's now working as well as remembered , it's probably not worth twiddling any more.
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