As a youngster I had always wanted one of these sets and couldn't resist the temptation to buy this one. As was common practice, an S'meter has been added to the front panel at some stage of it's life. A standard Cr100/2 would of course have a Bakelite watch holder mounted in this position. The handbook describes its construction as being of 1/16" motor body steel. I make that 2.5 times the thickness of the panels on my old Vauxhall.

• Circuit - 11 valve superhetrodyne with 2xRF and 3xIF stages.
• Range - 60-420Kc/s, 500Kc/s-30Mc/s
• Sensitivity - 1-2uV for 20db signal to noise ratio on CW up to 18Mc/s. 1-4uV above 18Mc/s
• Weight - 82lb
• Phones - High or low impedance
• Supply - 200-250 vac @ 85watts or 6vdc @ 8amps
• Dimensions - 16"w x 16.5"d x 12.5"h

Here's what GI3YMT in Belfast thinks about the Cr100.

"Many of you will remember the Marconi main receiver. Its heyday was from pre WW2 until well into the late 1970's and perhaps later. It was an all valve superhet whose technology was from the 1930's. It was a fairly dreadful receiver, perhaps OK until the early 1950's, but British ship owners insisted on using it for as long as they could. No doubt it was cheap to rent.

It was very unstable in tropical areas of the world and I have personally spent numerous hours 'finding' the station I was trying to work on H.F. Once found the mechanical scale reading would be noted. However if the temperatuire of the radio room changed then the setting would simply change and more search and find would be needed. Its performance, like all valve receivers of the time, fell off dramatically above about 14 Mhz. Working Portishead on 16 and 22 Mhz meant listening for watery weak signals moving all over the place. One other annoying thing about this receiver was its great ability to seek out anything on board with dirty commutator or contacts, perhaps a fridge motor or a rheostat etc etc, the list was endless."

Harsh words but very true I'm afraid.

These next series of pictures were taken by Les Carpenter and show one of his many B28 restorations. When I first saw these they blew my mind.

Before

This particular chassis had been given to Les after it had suffered a major fire which took out the mains transformer and all the wiring etc. It was also missing amongst other things, all valves and screening cans. At this stage I personally would have salvaged what I could and dumped the rest without a second thought. As you can see in the next series of images, Les did something else.

After

He stripped the set down to bare chassis and rebuilt the whole thing using B9A valves. The chassis by the way is painted. It certainly fooled me, I would have waged that it had been plated.

I'll let Les continue with the story.

"Yes I agree, I was a bit naughty with this re-build because due to the original state, i.e. fit for the junk yard only, I decided to bring it back to life regardless and without any thought for originality. The reason why I had to go to miniature valves was because of the screening can problem. None of the original cans or screening tops were available, all missing and these receivers can become very unstable without them. I tried to acquire some cans so I could use the original KTW61 valves with Octal bases but though I managed to get a couple the task of getting the whole lot seemed impossible. Because I happened to have plenty of B9A bases with skirts, I decided to use them, first making circular adaptor plates cut for B9A and then pop-rivetted into position using the original Octal base fixing holes.

All of the original 0.1uF high voltage caps were leaky so these were unbolted and I placed earth tags with nuts and bolts to fill up most holes. These were used to ground standard axial 400v capacitors which I bought from Maplin.

I could have replaced the rectifier with solid state diodes and fitted something like a EL84 for the audio output but decided against this. First, the original electrolytics were kept and no doubt prefered the slow HT rise you get from a valve rectifier rather than an instant 250V! The audio output valve does not have a screening can so I kept with the usual 6V6 output valve though I did fit the smaller GT glass versions to both the rectifier and output valve positions.

I have re-built six of these radios now, all have been derelict and ready for scrap. The paint was acquired from Halfords, I gave the chassis work a light rub down with emery paper to get rid of the rust then painted on a rust neutraliser. When this had been done, most of the chassis had turned black! I then gave the chassis numerous sprays of zinc paint and then a spray coat of red oxide paint, all available as car spray paints. Final finish was done with Halfords metal finish spray paint to make it look like it was plated.

the original front panels produced by Marconi were simply painted dark blue and the legends were applied using white paint and stencils, these can be found mainly on true B28 receivers built for the Royal Navy. Later models made for the RAF were given the CR100 status and had engraved front panels. What I did with my receivers was to give them the same treatment as the chassis but used white primer spray instead of red oxide. A good heavy spray of light blue followed which I think from memory was Ford Olympic Blue meant to be sprayed on Ford Capri's! I used a light blue as this would allow me to use standard black transfer lettering, I use ALFAC, most important, because Alfac lettering is not dissolved by acetone based varnish like some others I know, particularly Lettraset. When the lettering had been applied the delicate job of protecting it had to be undertaken. Again Halfords do some very nice clear lacquer (paint code 1950) and this is applied very lightly but with many coats. You have to be patient to allow each coat to dry before applying the next. Eventually you build up a thick clear covering which is very thorough and makes the fronts look fab.

Restoration took many weeks, it was not a continuous job as I had little time to spare but slowly we brought it all together. Dismantling all the I.F. cans was not very pleasant but each needed re-wire and besides I had to find the all important crystal frequency in order to re-align the receiver to when restoration, or should I say more correctly, rebuild, was complete. Performance is outstanding with the EF89's and for good measure I fitted a EF183 in the first RF amp which gives me even more gain. It's performance is now on a par with the later naval B40 receiver and even more excellent on the lower frequencies. As with most of these radios, the performance at the top end is a bit down but on this rebuild the performance at 30MHz is very good and copies well all the CB operators on 27MHz.

The screening cans, transformer and small metal piece parts were sprayed with Halfords Peugeot Silver (Met) paint code 453399. You can clearly see the adaptor plates around the B9A valve bases in the photo of the under side.

The front panel shows a little blue cube. This was a metal connecting block for wiring in the R.I.S. This stands for Radar Interference Suppression and is used to remove interference from the Radar onboard ship. The small red front panel knob adjusted the amplitude such that the Radar sample pulse fed into the block could be adjusted to cancel out the pulse being picked up on the receivers aerial and thus removed it from the audio output. The interference would otherwise appear as an annoying buzz. The blue cube in the picture was originally missing, I could not get one so I made it out of wood then sprayed it Blue."

Les G4CNH.

I have edited the text a little just to keep it in context. I'm sure you will agree that this project really deserves it's own web site, wonderful stuff, well done Les.