Plessey PR152 info

[Denwood]

Hi,
Is anything known by the group about the Plessey PR152 receiver?

No, I don't mean the PR155! This is a single-conversion superhet with a ~1600kHz IF and an impressive film strip dial. It has Ge transistors and dates from the early 1960s.

I have one in good cosmetic order that I'd like to get going. Any information (and especially a schematic) would be welcome.

A small pic is attached. I have high-res photos if anyone is interested.

Regards,
Murray ZL1BPU

[Station X]

One post deleted because it broke forum rules.

[Alistair D]

Try asking on this site as well.

http://www.vmars.org.uk/

Al

[TonyG8BPW]

Denwood, Plessey Receiver PR152 did you find your information? I have just dug my 152 out of the atic and have only just seen your post, worked on a couple of these at Plessey many years ago. Sadly the only real good thing about the PR152 was the excellent film scale mechanisam. Apart from the range switching uinit with its 3 gang tuning capacitor I thought it was a straight forward AM double superhet, first IF 1.6mhz second around 455khz.
As your post is so old I have not looked for the circuits as they may take some finding.

[AC/HL]

Welcome Tony,
Denwood hasn't been active for over a year, but you could try emailing him.

[Denwood]

Tony,
My Hero! I've been watchig the posts to this forum every day for the last two to three years, hoping that someone would have some information.

Yours is the very first positive news, and I look forward to more information when ever you have the opportunity.

I agree, the PR152 is unlikely to be the world's greatest radio, but since mine is in excellent cosmetic and mechanical condition, it seems a shame not to have it going again.

I had a feeling the 1st IF was 1.6MHz, but I know so little about, I did not even realize there was a second IF. I have no information about it at all. If you do have a circuit diagram or manual for it, I'd be extremely pleased to receive a copy.

When I fired it up, nothing much happened. I'm reluctant to go further without more information, so the receiver has sat in the cupboard waiting for some kind soul to come to its rescue!

Thanks in advance and 73,
Murray ZL1BPU

[turretslug]

Given that there's been a fair amount of musing on the whole thermionic/bipolar/FET/IC transition on the forum recently (with significant input from a North Island member!) with HF receiver techniques as a prominent topic, an "interim " set like this is always of wider interest. Even if it won't frighten an R390A or an RA1772.

Re. "nothing much", I imagine that "AF11x ?" will be in a lot of people's heads... Good luck with it. I like the way that it at least makes the effort to split the "usual" wide span on the top HF range into three smaller chunks (a la AR88).

[Radio Wrangler]

Valve-transistor transition sets *are* interesting. Their performance may not be wonderful, but they represent a special period in the evolution of the HF receiver. I keep an RA1217 for just this reason.

Two to three years would have been long enough to have traced out the circuit. But why not open it up and take a load of photos to let the lot of us bring our combined curiosity to bear on it. It's a receiver I've not come across.

David

[Denwood]

Guys,
I've taken a few photos of the Plessey PR152. If all goes well, they should be visible at:

https://www.dropbox.com/sc/n02hft8n4a9a6gi/mj8oSo7jQT

Let me know if you can't find them.

I could post them here if necessary, but would need to reduce the size first.

73,
Murray ZL1BPU

[Radio Wrangler]

Excellent photos and very interesting.

It's got a good collection of components which are on the swap-on-sight list. There's only one IF bandwidth, with an audio filter done in those pot cores to sharpen it up for CW. There's no way to turn off the AGC.

The calibrator gets a crystal, but the IF isn't so honoured. It's a bit like an Eddystone EC10 with better bandspread.

I don't like how mains enters at the little bulgin connector, goes to the mode switch on the front panel and then is wired back to a connector to go to the power supply module. Without that, the thing would have been safe to work on. I'd use DC power when working on it. I'm just a coward.

Now the mystery is what market was it made for? It's definitely not a competitor for the tail end of the valve receivers.

David

[turretslug]

Indeed interesting, plenty to chew on here. A fine example of designers/manufacturers in a sort of limbo between point-to-point and PCB techniques. Transistors aside, the 3-gang front end is lifted from the era of my Pye CAT or Eddystone 750 (also dual-conversion lightweight compacts), the IF and audio bit wouldn't look so wrong in '70's production. I wonder if that slightly toe-curling mains pack is an option to swap for a battery box? I get the feeling that that Bulgin mains is a mod, perhaps a Jones-type chassis plug did the mains interface originally.

Those red-and-black Plessey cups are strongly jostling with crumbly brown Hunts, sweaty Micamolds and smokescreen Rifa mains caps for top place in eradicate immediately stakes. At least the replacements will be so much smaller that they'll connect to snipped tails without long-winded dismantling.

Definitely, as said, the film-scale mech is the high point- once the RA17 had set the ball rolling, designers with professional aspiration could hardly not use it. Yet it would have made it almost a military-only price, but without the expected performance. No wonder it's a rare beast.

[G6Tanuki]

Fascinating: the IF/AF board with its wiring style and collection of gold pre-TO5-can GEC germanium transistors reminds me of early-1960s valve/transistor hybrid Pye [Vanguard/Cambridge]. Though the Pye stuff generally had a lot less in the way of fiddly inter-board wiring.

I particularly like the two "GET" audio-output transistors in their black finned heatsinks - the only other instance I've seen of these devices being used is in industrial and telephone-exchange applications [Plessey made a lot of telephone exchanges too].

[Another thought: why was so much use made in that era of pink interconnecting cableforms? It must have led to lots of inadvertent mis-wirings during assembly. Plessey carried on using this approach up to the 1980s. Look inside a PRC320 and _every_ wire is pink!].

The overall design of the PR152 makes me think its production-costs must have been extremely high which hints at a bottom-of-the-professional target market (and/or explains the rarity of these receivers!) though the absence of a crystal filter would - even in the 1960s - have been a big issue for many communications applications.

Definitely fascinating though - and one worthy of keeping even if it doesn't perform too well.

[Radio Wrangler]

THere looks to be a later type of diode added at the DC input connector... ah, it looks like two in parallel! Methinks I see the fine work of the phantom bodger, or at least someone who doesn't know that diodes don't share current very equally.

An anti reverse polarity diode is a very good idea, but it needs to be done with anadequate part.

I don't seem to see a proper mains switch appended to the mode switch so does that mean Plessey put mains on an ordinary SRBP switch wafer? However, the bulgin connector does seem to be stuffed into a square hole and themetal plate has other apertures suspiciously shaped for panel mount fuseholders a bit later in period than the set. Hmmm. Does that extension to the cutout in the rear cabinet cover look original? I'd have expected another strike with the same punch as made the DC plug hole.

It's also got a modification strike-off label on the back as well.

+ve earth. Inconvenient nowadays.

THe batt test switch position suggests a battery box in place of the mains unit.

And who would have wanted one? As it didn't catch on, maybe a better question is who was expected to want them?

David

[Skywave]

Originally Posted by G6Tanuki

Why was so much use made in that era of pink interconnecting cableforms? It must have led to lots of inadvertent mis-wirings during assembly.

I was working in Government R & D radio & electronics during the mid 1970s when an edict was issued that the wiring of all new equipment was to be by using pink wire only. To avoid wiring errors, numbered sleeves were to be inserted at the end of each length of pink wire.
That edict superseded and replaced the previous scheme of using different coloured wiring for different types of connection, e.g. the traditional red for +ve PSU, black for 0v., etc. The change was brought about by the ever-growing complexity of circuit inter-connections where the limited range of colours would be inadequate to uniquely distinguish between the myriad of connections that were then becoming commonplace in electronics equipment. (Digital electronics was then starting to make serious appearances in designs). Even the use of twin and triple colour coded wiring was considered to be inadequate to cover the needs for such interconnections.

Al. / Jan. 26, 2014 //

[Denwood]

All very interesting guys, but what I need is the manual, or at least the schematic, please! Have a hunt through your old books and magazines for any technical details too.

I agree, those electrolytics will have to go staight away. I'm hoping that I should not need to remove the boards to repair it, for as commented, all the wires are pink - who had that bright idea?

I can tell you about the AC supply. Yes, it is a separate box, probably an optional extra, which sits in the space where the square-type batteries would have gone. I would imagine it came with the harness and Bulgin socket for the AC side. Not very safe by modern standards. I will have to take the lid off again before I can tell you how power is switched. By the way, I do have the power cord for the radio.

Because of its rarity, the PR152 is definitely worth restoring, never mind that it won't be a top performer.

73,
Murray ZL1BPU

[RobinBirch]

Yes, we went through a stage during the 70s and into the 80s when everything was pink if it was a signal wire. Very confusing until you got used to it.

Robin

[emeritus]

I still have the remains of a 100m drum of pink stranded wire from my Plessey days working on MOD projects. Somewhere in the loft are some of the slip-on alpha-numeric sleeves in a range of sizes that had to be slipped over both ends of cables and wires to uniquely identify them.

[TonyG8BPW]

Re the Pink wires they should all have ident markers on them the coding is the same as resistors. I will try and find my hand book with the circuit diagrams. Mine is basically now working after liberal use of switch cleaner.
I used the 152 in the early 70s as a receiver to tune a 144mhz converter, slope detected the FM. The days of tuning high to low.

[Herald1360]

Ahh, memories.......

"CQ2, CQ2, CQ2, this is G8EYC calling CQ2. Tuning 144 decimal 3 up......."

(Microwave Modules 4-6MHz converter, AR88LF RX)

[Denwood]

Hello! I'm here again, with good news.

I still have not found any info (manual or schematic) for the Plessey PR152, but I now have it working!

The performance is surprisingly good for a 50-odd year old radio. No exact measurements yet, but my impression is that the sensitivity is good even up to 20 MHz. The 1600 kHz IF is a bit broad, but short-wave reception is impressive.

What was wrong with it? Blessed if I know! I started taking it apart to understand the circuit, measure a few voltages etc, and discovered at one point that there was hiss from the speaker. I added an antenna, and amazingly, it was all working. I can only assume that I disturbed some mechanical fault in the dismantling. Let's hope it stays going.

I'll report back when I've made some serious measurements. In the meantime, back to lurking...

(Photos of the PR152 are at https://www.dropbox.com/sc/n02hft8n4a9a6gi/mj8oSo7jQT)

73,
Murray ZL1BPU