Roberts RT1

[David G4EBT]

I'm not a fan of Roberts (or Hackers for that matter), as much as anything because as was common in their era, they have PCBs with an SRBP substrate, and at the mere sight of a soldering iron, however much care is taken, the tracks lift off the board, and it's all downhill from there.

But as sometimes happens, a little while ago a neighbour said "you mess about with old radios don't you?" ('Mess about?' - I beg your pardon!). He had a Roberts RT1 in his hand and I thought he was about to say: "Can you get this going for me", but he actually said "Is this any use to you for bits - if not, I'll bin it". Can't resist 'summat for nowt' so it went from his loft to mine, where it's languished till now, so when having a sort out, I thought I'd give it a closer look. It was designed to be powered by the long since obsolete 6 Volt 'PP8' battery, (now seemingly only available as a 'PP8/2' - two 6V PP8s in one pack, marketed as an 'electric fence' battery.

https://www.batterystation.co.uk/bat...battery-1-pack

I poked 6 Volts into the RT1 and it was lifeless - just a faint hiss. The two 100uF electrolytic caps looked corroded so I replace those and it came nicely to life. I replaced a harder to get at 8uF cap, and out of curiosity, replace two of several Hunts mouldseal caps. Tested them at 750V - no leakage and still 0.1UF so didn't bother with the rest. A squirt of Deoxit into the volume control and the wave-change switch contacts sorted crackles out. Cleaned it up a bit - not worth spending too long on it. It performs really quite well, helped by the largish Rola speaker.

I could have just popped a 4 x AA battery holder into the set, but I found a battery scan from I know not where, so made a replica battery by making a box to house the battery holder from some bits of scrap oak, and attached the scan. I made the end from 2mm thick Paxolin, covered with a scan of the battery and, attached a couple of 'press stud' battery connectors and fixed the end panel with four small CS screws.

One thing that puzzled me, which Roberts fans may be able to answer, is that there's a plywood 'turn-button' which must have had a use, but I can't think what. I assume it as ho hold something in place, but not the battery - leastways, not a PP8 battery. I've attached some pics, and maybe if anyone does have a definitive answer (rather than a speculative guess), I'd appreciate a comment.

As will be seen in pics 3 & 4, the PP8 battery extends beyond the turnbuckle and it would make sense if the turnbuckle was on the RH side of the plywood support, as it would indeed restrain the battery from sliding about. I'm wondering therefore if this was a manufacturing defect - it looks entirely original.

The RT1 dates back to a time when engineers designed items with little regard to cost, and accountants worked out the price with little regard to marketing, on a cost-plus basis. The cost of something is labour, plus materials, plus overheads. The 'price' is (should be) what the market will stand - not simply a mark-up added to the cost.

The RT1 retailed in April 1958 at £17 8s 9d including battery, plus Purchase Tax. In the 1950s, purchase tax on radios was I believe at two rates: 5% on the cabinet (treated as ‘furniture’), and 50% on the electronics. It was up to the manufacturer to apportion the extent of the retail price was which, but simplicity, I’ll assume 50% overall. So, £17.45 (in new money), plus £8.72 P.T. = £26.17. At 2018 prices when adjusted for inflation = £581!!!. Strewth. I wonder if anyone realised that the light they saw at the end of the tunnel was an oncoming train, and not a gravy train at that? Not just Roberts fate of course.

http://inflation.iamkate.com/

For comparison, the Bush TR82 came out in May 1959, costing 2 old pence more than the RT1 at £17.8s 11p (those accountants again!) plus P.T.
A much nicer radio, far easier to repair, and with a tone control.

Incidentally, ‘communications receivers which had a BFO – some Eddystones for example - were exempt from purchase tax.

I'll start another thread about the replica PP8 battery in case it might prove useful.

[ms660]

Turnbuckle...PP1 battery.

Lawrence.

[Paul_RK]

Yes, the turnbuckle was introduced in the course of production to keep the alternative PP1 battery from moving around. Later RT1 instruction leaflets refer to its use, earlier issues just say that a smaller 6 volt battery than the PP8 can be fitted if wished.

Paul

[David G4EBT]

Thanks Lawrence - that was quick!

There's a link to a currently available replacement PP1 here (a bit on the pricey side - more than the radio is worth!):

http://www.smallbattery.company.org.uk/sbc_pp1.htm

The description states: "this PP1 battery uses the original carbon-zinc layer cell technology to deliver a long battery life". It gives the dimensions as 65.1mm wide x 55.6mm deep x 55.6mm high. That's not necessarily the original dimensions, but from the scan available at the link below, it seems to be. I've checked the space in the RT1 to the right of the turnbuckle, and the space is only 50mm x 50mm x 50mm, but clearly the intention was to give two battery size options, so thanks for sussing that out.

https://www.bing.com/images/search?v...x=1&ajaxhist=0

['LIVEWIRE?']

A few months ahgo I repaired an RT1 which had been dropped, cracking the PCB around the driver and o/p transformers. After making good the severed connections with 18SWG tinned copper wire, and replacing several capacitors, the radio worked very well. I wrote it up in 'Success Stories' at the time. The cabinet wasn't in as smart a condition as your RT1, David, though it did clean up well.

[David G4EBT]

Thanks Paul and 'Livewire' for reading and replying to the thread.

I've done nothing to the cabinet other than a quick rub over with foam cleaner, but I might try some red car polish, which I have in the garage. The strap has come apart as the stitching has rotted, and I'm not sure how the strap is fitted to the cabinet - it doesn't look easily removable. I've cleaned the knobs and dial, and got a couple of dents out of the speaker grille, but I think I'm going to have to put a bit more effort into its appearance, as whilst having - as they say in these parts, for reasons unknown - 'had my fussy out with it', I'd intended to pop it back in the loft as 'clutter', my wife likes the look of it and wants to put it on display. (If I make it look too pretty, if my neighbour sees it he might want it back!).

[Tim]

I have got one of these in the "rainy day" box. I think it's been there for about 25 years!

['LIVEWIRE?']

Two things regarding the case & strap, David. The one I repaired was in a green cabinet, which I treated with a green cream/polish from a local Shoe repair shop. This worked a treat! The handle is held in by two washers, one on each side, which are soldered to the pins inside the cabinet. These can easily be removed by gently heating the washers with a soldering iron. If the original handle is irreparable, a modern Roberts Handle could be fitted, but the pins on these are smaller in diameter and, more importantly, too long to fit in the RT1 cabinet. The only way to use a modern handle would be to either drill small holes in the two metal end plates of the RT1s chassis, or to shorten the pins, and find an alternative way to secure them (small circlips are used on modern handles, btw)

[David G4EBT]

Thanks for the info about the straps - most helpful, especially how to remove the strap from the cabinet. The leather and plastic on this one are in reasonable condition, but as with several examples I've seen on internet and the forum, as mine has, they seem to suffer from the stitching wearing out and the leather coming apart from the plastic. I don't know whether anyone has successfully repaired a strap by hand-stitching with a needle and thread, which would be more than a little tedious!

[Boater Sam]

Cobblers. Not an insult but they have machines that can re-sew straps or turn a belt into one.
I found the press on fasteners for these pin-on handles in a previous post, 'course I can't find it now.

[David G4EBT]

The only thing I'd wonder about is whether the needle would hit the same holes Sam. I doubt that the plastic and leather would stand another set of holes. Maybe I'll ask when I come across a cobblers - they seem to have become an endangered species, apart from the occasional Timpsons here and there. (The cobbler in our village (pop'n 18,000) closed down some time ago.