New Acquisitions

Voxon bass fifty amplifier

 

This old amplifier was donated by Alan Phillips, a visitor to the Radio Museum carrying duff lift circuit boards needing attention. I'd previously shown Alan my rebuilt Moreton Cheyney amplifier when he said he'd got something similar. It was only later I lifted it onto the workbench when I realised it was indeed similar because of its immense weight and having removed the rear cover and noticed the two hefty transformers.. Those output valves are Pinnacle-branded EL34s, and the name "fifty" maybe implies 50 watts output?

 

 
 

 The valves are a mixed bunch. The EL34s are Pinnacle and a Mullard with the two smaller audio valves both ECC83, again a Pinnacle and a Mullard. The rectifier valve is an EZ80, presumably for the EL34 anodes and on the right, under the chassis, is a selenium rectifier for the ECC83s. There's also a pair of silicon rectifier diodes.. maybe for the EL34 bias supply? Or the other way round as I haven't checked the circuit details.

As you can see below, from the printing on the mains selector panel (missing its shorting plug), the amplifier post dates the Radiospares change to "RS" in 1971 but my Hi-Fi year books are silent on the Voxon name.. at least in 1972/76/ 79. 

 

 
 

 Below a view under the amplifier chassis and then a view from the top. Most of the parts seem to have been sourced from RS. The mains transformer appears to have a date in November 1966 and the output transformer is marked 15 ohms and "785-80" (possibly an RS stock number?).

 

 

 

Audition Instruments Pre-amp/Reverb unit 

 

 

 Above...this preamp which came with the Voxon, at first looked like it came from the same manufacturer but when I looked inside it was completely different. It uses a couple of printed circuit boards marked "CDK TP-15A and TP-15B" and Toshiba transistors. From the crude build quality it looks British***. The badge states "Audition Instruments" but I can find no record of this nor the Voxon amplifier, although "Voxson" does appear mis-spelled as "Voxon" in a few places..
 *** You can see the construction in the pictures below. When I attempted to detach the chassis from the case after removing securing screws it wouldn't budge. I used a screwdiver as a lever and forced it out. The self-tapping screws holding the lower circuit board were far too long and prevented the chassis sliding into the case so it had been jammed in place. Wiring conforms to the "scrambled" spec and anyone that's handled Roberts radios from the same era as this pre-amp will recognise the general design and be aware of excellent performance coupled with incredibly poor mechanical design with little thought for a repairman. I'm reminded of a comment by a Plessey mechanical engineer (concerning some satellite ground station equipment) back in the late 60s... "the string is NATO approved string not just any old string".

 

 Inside the pre-amp case are two early printed circuit boards with the mains transformer on the right.

All the transistors seem to be PNP devices and are germanium rather than silicon based. The pair in the centre, mounted on heatsinks screwed to the lower of the two circuit boards, are Toshiba 2SB462 with the "B" standing for PNP. The case style is TO66 dating back to the 1960s.

 

Maybe the marking "CDK TP15" means something to somebody? 

 

 

 *****

 BC221M

 

 

 

 

 Another item from Dave G3SUL is this BC221 which is a different model to my previous BC-221-AF example seen here. The availability of these equipments back in the 50s, 60s and 70s provided a convenient way of meeting the terms of ones amateur radio license although actually having one to show a GPO inspector didn't always mean it had ever been used.

 

 

 Dave also gave me this wooden box. It contained a rather nice 550-0-550V transformer, not the original Type 2 Crystal Monitor, whatever that was?
 

 HP Spectrum Analyser

 

 Dave, G3SUL kindly donated this equipment which comprises the HP141T, HP8552B, HP8553B, HP8554B and HP8556B (together with a few very nice 1930s radios which are pictured below, together with a nice clean RA17). As you can see the spectrum analyser is in immaculate condition unlike my usual Hewlett Packard acquisitions. Timing is amazing because I was just about to go searching for a low frequency spectrum analyser with which to investigate my current amplifier rebuild. The 8556 works from 20Hz to 300KHz and includes a tracking generator and I'm hoping this will let me measure the quality of the amplifier in terms of linearity and distortion. Below some radios donated by Dave, G3SUL.

 

 

 Marconi

Model 219

Read about the overhaul of a similar example for a customer in 2014

 

 

 

 This generation of radios from 1936 often used a fashionable shiny brass grille over the speaker. I removed the speaker assembly and found the grille was really badly tarnished but turning it over revealed the other side was in fair condition. I glued the cloth in place and fitted the grille which restores the radio's looks.

I use a brushing wax to restore cabinets and once applied looks OK.

Below its unusual audio output valve, an MPT4.
 

 

 

 Ultra Lynx

From 1931

 

 

 McMichael

Model 364

from 1936

 

 

 
 

 A very clean example of the RA17 with S/No. N2866.

 This has a few faults that need clearing up.

See how I'm getting on...

 

 Skanti TRP8255

 

 This is the Plessey-badged transceiver fitted in the HDRS, later NCRS, cabins that were supposed to carry army radio traffic to attempt to bring order back to the UK, devastated by nuclear war.

Thankfully the possibility of this ever happening caught MoD off guard leaving the project high and dry.

 

All advanced projects go wrong because of software problems and HDRS was no different. MoD were more to blame than Plessey because sensible timescales and costs were always secondary to available time and cash.

The more a project is starved of timescale and finance the worse things can get. HDRS wasn't really required but Plessey managed to get the thing delivered under the guise of a sort of plaything for the Army.

Later the whole thing was sold off at bargain basement prices and here's one of the radios I bought from a fellow radio ham...

 

Read more about the Project.. which for a period I had the dubious pleasure of managing.

 

 

 
 

 HP8640B Signal Generator

 
 

 A gamble at a fraction of the price of a decent example, this sorry-looking RF signal generator heavyweight originally cost thousands of pounds but damp and neglect has made it cheap and not so cheerful. Can it be restored, at least to a working state?

click to see more...

 WS19 Mk3

 

 

  This working British Wireless Set No.19, rebuilt in 1960, came from Geoff G4ICD, complete with its power supply (below) which just needs a few wires adding to complete the HT2 supply which is required for transmit.

Click the picture to see more

 

 
 

Plessey PR155G

 When I saw this advertised for sale it was something I couldn't not be interested in, as I worked for Plessey Electronics at the time this was made. It has a major advantage over slightly later transistor-based radios as it doesn't use a microprocessor so should be easily maintainable and radio amateur-friendly. It's similar in operation to the Racal RA17 but isn't anything like as bulky and, although it's heavy (38 pounds), uses relatively simple modules that mostly use nice readily available parts. The receiver would have been designed by the Plessey R & D establishment at Southleigh near Havant. Close by was the Plessey factory at West Leigh that made these equipments. I used to visit both sites donkeys years ago but in connection, not with radios, but anti-terrorist equipment including metal detectors (eg.P6), wire detectors (eg.P7) and intruder and sniper detection equipment (eg. IA2). They also experimented with optical fibre equipment but as it was years before a demand for such stuff it wasn't really a high priority. My last project, HDRS was designed at Southleigh and manufactured at the Plessey factory in Ilford.

Click the picture to read more

 

 Relay

 

 Searching for my three Grid Dip Oscillators which I put together in a box then promptly forgot where I'd put it, and as a last resort searched the loft above my workshop, I unearthed some stuff I'd forgotten I had including this old Air Ministry relay. As you can see it's marked "RELAY UNIT TYPE 125" with the RAF code 10E or 10F/16827. It's possible those three PL259 connectors replace the UK type of RF connectors used in the 1950s?

The box is marked "24 volt" at the 2-way connector.

What was it used for I wonder?

 

 
 

 Wavemeter W66

 Click the picture to see more

 

 R1155A Receiver

 The serial number plate is not very clear but does have the serial number 42156, and it's an early model with the older tuning knobs. I bought it because it appears to have been unmolested except perhaps for that pair of wires emerging from between the connectors. The date on the front panel of 14th January 1949 may indicate that it's been overhauled, possibly having been fitted with a nice new dial and perspex cover?

A lot more complete than my others and see more of this example.

 
 

 A Gumtree Purchase

First a N.O.S. T1154N 

 Tucked in beside the transmitter I found a N.O.S. throat microphone and a set of aerial plugs etc for the T1154 (scroll down to see these). The case needs a little TLC as dreaded woodworm is evident. I think these have now wandered off so hopefully the case can be restored...

 

 


 Next an R1132A

 


 Next, a rare 16 valve receiver with which I'm not familiar marked "Moreton Cheyney"

click a picture to see more

 
   

 Then a high power amplifier/PSU

click to see more

 

 I suspect this lot were originally in the hands a now silent key radio amateur. They were given as payment for some plastering work many years ago. I initially thought this heavyweight chassis was a modulator for an AM transmitter, but as it has two leads terminating in plugs which match the Moreton Cheyney receiver I'm now thinking it's the audio amplifier for the Moreton Cheyney receiver?. That's one surviving KT66 up there and a couple of EF37 valves hidden behind the transformer on the right.
 

 

 And finally in the job lot were two bonus items, a throat mic and a set of T1154 connectors

 


 Naval Receiver CNY-2/W5737

 

 

 

 I got this receiver recently when it was destined for a skip but it looks almost complete so I've decided to see if it can be restored to working condition.

Click a picture to read more
 

 Telegraph Repeater

I'm unsure as to what this object is exactly, but it might be a telegraph relay or repeater? More pictures will follow.

The name of the manufacturer dates this to after 1880 when Siemens Brothers & C. Ltd was formed from the earlier company.

It was kindly donated by Simon Cole from Westcote Barton.

 

 Old Microphone (not a balun!)

 

 Another interesting item from Simon. I thought it was a balun, then a tweeter but a quick search revealed it's a microphone not unlike those used by the BBC from 1938-1951. No mounting bracket so may have been clamped and suspended somehow. Serial number 2793.

 Portable Linesman's Phone (June 2019)

 

 

 The above telephone was discovered in an attic and kindly donated by Paul Berry from Burley.Apparently it's a Type 44 for non-military use and the absence of a lid is because it originally came in a leather case.

Click either picture to see more.
 

 Wireless Set No.88 (June 2019)

 

  Another early VHF transceiver

Click the picture to read more about this little set

 Wireless Set No.31 (May 2019)

 

 Despite the numbers showing in the dial, this is a VHF FM transceiver and not for use in the HF bands.

Click the picture to read more about this set.


 Andrus SDR (May 2019)

click the picture to see more

 
 

 Measurements Corp. GDO Model 59

 

 

 This old frequency meter arrived today.. 9th May 2019 and looks Hallicrafterish.. It needs a set of coils made to match its dial and at first sight it seems to be a hand-held signal generator covering 2.2 to 420MHz. All will be revealed when I open the case... Yes it's a signal generator and it uses a 955/VT121 triode. This valve was introduced in 1935 and is to be found in several WW2 equipments.

After a little investigation I found the meter part would have plugged into a power supply box, via its cable terminated in an octal plug. The PSU box carried a meter indicating the valve's anode current, making it a grid dip meter.

 

 

 The only maker's mark on the instrument is this logo accompanying the code "SER.748". It looks a bit like an anchor, but I prefer a meter.

The manufacturer was "Measurements Corporation" of Boonton, New Jersey and below are advertisements from 1952 (above) then 1950 (below) depicting the GDO.

 

 


 TS-184A/AP

 

 Above, from 1944 is a piece of test equipment which I was told was used to monitor IFF broadcasts from aircraft. As it's pretty rare I'll need to investigate its pedigree and it's very surprising to see it's survived over 70 years without being canibalised for parts. Click it see more of it...


 R3673 Receiver

 
 The R3673 forms part of the last version of the GEE system developed during WW2 for accurate bombing. It uses lots of all-glass valves, mainly the EF91 in place of the SP61 or EF50 valves and embodies all the RF and processing circuitry within the same box and is remotely controlled via cabling. See a mention of the system here.

 R210 Receiver

 

 The above aquisition is a prototype of the receiver. Click the picture to see more of it.

 R216 Supply Unit Rectifier No 24

 

 I picked up this power unit for my recently acquired R216 receiver (see below) and will take the place of my home constructed PSU.


 Solartron HT Power Supply

 Similar to this one but a few years newer

 


 LeCroy 9450 Digital Oscilloscope

 

 This rather fine Swiss-made oscilloscope dating from 1990 and the Solartron power supply were given to me by Steven who spotted my old Solartron and thought a second would come in useful. The scope has a fault that's eluded other repairers.

Click the picture to see more.
 
 

 R216 Receiver

 
 

 

I wanted one of these receivers when they first appeared as government surplus but they were too pricey for me. I'd imagined the R216 was just a VHF version of the R206 which I bought in 1958 but of course their design is ten years later (although it does have a turret tuner). When Leighton, GW3FSP advertised his for sale I was first in line and the set arrived here after a week or so.

 

 


 DST100 Communications Receiver

 


 Strowger Relay

click on the picture to see more

 

 Low Voltage Stabilised Power Supply

click the picture to see more

 

 

 Doolittle PR7NA

US Navy receiver made in 1944

click the picture to see more

 


 

 A Resistance Bridge made by Elliott Brothers

 

 

 A Lissen Kenilworth with push-button tuning

Model 8543

 
 

 

 This sign has been propped up on our window ledge pointing up the stairs for the best part of 25 years.

Does anyone recognise it?

 Toyo 100Watt Dummy Load

 A useful dummy load which turned up recently. I wonder why it's spec starts at only 3.5MHz and what's the significance of "M" and "N" on the curves? This has a PL259 socket so I wonder if "N" implies there's a version with an N connector?

 
 

 An old REVO electric fan from the early 1930s I think?

 

 

 This came fitted with an old two-pin 2-amp plug commonly used before WW2 and, on the underside, the makers' name "Revo" Model? "12" and Serial Number 62384.

 

It bears a marking for 200 to 220 volts 50 Cycles but etched next to this is "240 volts".

 

I haven't plugged it in because the wiring is a bit too brittle for my liking.

 

I think there are plenty of Electric Fan followers out there so maybe one would care to comment on the Revo's true age?
 

 Sony CDP101

 I was tidying up the workshop when I found an old CD player. It was left over from the days I used to repair such things and I recall this particular thing belonged to me rather than a customer. Repairing CD players was a tricky business. Usually one could buy a complete optical mechanism for a few pounds and drop it into place and the player would work like new, however, some manufacturer's models used very unusual optical units whose replacement cost well over a hundred pounds. These equipments were automatically consigned to the scrap heap because prices on new players had dropped to less than £30.

For some reason I'd kept this Sony player and today I looked it up on the Net. It turns out to be the first commercially produced CD player so is definitely worth keeping. These players sold originally for over £500 in 1982 and working models still fetch well over £100.

 
 
 

 Philips N4418 Open Reel Tape Recorder

 

This is the Philips Model N4418, their top of the range open reel tape recorder in the 70s.

I picked it up for £10 from the local recycling centre after filling in numerous forms, presumably to imdemnify the workers, local council officials, the UK Government and Brussels beaurocrats if I accidentally electrocuted myself when plugging it in. Absolute and utter nonsense! What's the world coming to?

Fortunately the mains lead was intact, tucked into a little compartment. Were the recycling people breaking some sort of law not cutting it off!

£10 was a lot of money considering the showroom was not available for demonstrations, but I was very pleasantly surprised when I plugged it in, and switched it on, to find it was in perfect working order.

Even the perspex cover is intact. The only faults I could find were a slipping belt on the tape counter and a faulty bulb in the RH output meter.

Considering that the price of the machine when new was about 50% of a small car such a mini, £10 wasn't bad. As the chap said when he quoted £10, "collectors are after them". Well one was and I'm very pleased I coughed up the cash.
 

 Horn Loudspeaker

 

 An early horn loudspeaker

Standing on a mahogany base and having a lacquered brass adjuster and connectors, this loudspeaker probably dates to around 1922 or 1923. It was made by S G Brown who were a leading company in the early days of audio amplification, particularly of crystal sets, using magnetic amplifiers, before valves were commonplace.

This example, which has a horn opening of 12" and stands 21" high, appears to have been restored, or at least repainted. The impedance of the energising coil is 4000 ohms and would have been ideal for connection to a crystal set in place of the usual headphones.
 

 Some old valves

When you see these scroll up the page for a couple more...

 Latest collection of valves

 See more stuff not yet included in detail

 Return to entrance