Hi,

Anyone here has any knowledge about these radios .... has one .... refurbed one etc ???

I have one that I will be refurbing soon. Just starting to gather info, videos etc..

Cheers, Ian

I may be able to get access to a technical manual for that, if you need it.

Hold that 'thought' GTC ... I have been gathering lots of documentation .... web pages, restoration articles etc .... which includes a couple of Manuals. There were many Versions of this radio manufactured, so I am checking through the Manuals I have to see if any match my radio.
If not, I will contact you,
Thanks ....

It may also appear as a HMV. There is a HMV 5101 / Marconi 7101 on my bench. Its now mine and was a mess from a restoration that had a few issues.

Live metal 6L6 that should be KT66, a short, bad mains wiring, issues with the wiring around its wrong volume pot, like a cap with an end in mid air? Seven dry joints; It was supposed to work? Yeh! It has an Airzone 609 to keep it company, it has two caps with ends in mid air, so it may also prove an interesting thing.

Marc

The Marconi R1155 is a military receiver used in aircraft in WW2.

Yes, specifically designed for use in aircraft, but later adapted to Marine and Land based uses .... and then Amateur radio.

Apparently, quite a few 'restorations' stuffed up the power supply changes required when converting to Amateur radio use ... live chassis, no Bias, burnt out valve Heaters etc etc..

The articles on this radio are very interesting.
Including that for aircraft the chassis was aluminium and for marine steel.
JJ

Some of the aircraft stuff could be tricky as some (Bristol ?) ran 400Hz Alternators.

Marc

Hi all,

GTC - thanks for the offer of tracking down a Technical Manual etc, but I have found several ... some applicable, some not. Seems that the original documentation together with a 'reversed engineered' circuit diagram by another Owner are relevant to my R1155.

Marcc - yes, a separate PSU is required and care is needed as the circuit requires the HT to float, referenced from the Negative Bias -ve, with Negative Bias +ve (I hope that makes sense) is Chassis.

Just a bit of background ... my R1155 has the Direction Finding stripped out except for some snipped off wires ... this is very typical for many of these radios (sold into the market as Surplus, then modified by Amateurs/Hams) ... otherwise it seems to me to be quite original. Has AM badge, Jones Plugs, early Tuning control, good colours in frequency ranges, original valves and covers, shielding, stamps etc ... however, the wiring insulation is brittle and all caps are old etc..

As yet I haven't started any restoration work ... still in process of checking components, circuitry etc to make sure I know what I have. But, I can see that any removal of parts for replacement or checking is going to cause problems with wiring insulation ... a long-term project.

Cheers, Ian

It is not uncommon & Astor seemed to be an offender at using the lowest grade stuff followed By Mr Thom & Mr Smith who helped in particular heater & filament wire insulation die, using scanting & they got hot.

Some of that I am sure was biological attack as the stuff in the RF hostile areas, tended to survive. The last bit of Military clobber of significance as its mine. Was a BC-221-N, US Frequency meter. Clearly not designed by a German, it was really designed to be tossed if it blew more that the spare valves it carried. It was full of nasty PCB oil filled caps. They were leaking electrically & the PCB was getting out from the rubber seals deteriorating.

It needed caps & several resistors. For sets like that one can design a PSU just for it and I will often use a 79xx as the bias on a separate winding to the rest. For stability & hum control, I would be tempted to use DC on the heaters. For HV a LR8 shunting a TIP 50 is an option.

At its age I would toss all waxed paper & electrolytic caps.

Marcc

Hi all,

My Marconi R1155 radio is now alive (no Direction Finding circuits) .... sound from several Bands. It still needs a full re-alignment and other adjustments to get it running properly etc ... and maybe then some cosmetics.

It turned out to be a bigger job than I expected ... Varnish splashed on every thing, screws super-tightened and 'aged', lots of crumbly wiring needing replacement, poor previous modification work necessitating the tracing of nearly every wire etc etc.. I guess that the higher quality workmanship of the original manufacture (ie varnish and component securing etc) was needed for the environment that a Lancaster Bomber operated in.

This radio was originally run from the Lancaster Dynamometer but had been converted to ac valve heaters. This has been retained for the moment. Once properly aligned etc, I may convert it back to dc heaters if 'hum' is a problem. I built a separate PSU with 'floating' High and Low voltage supplies to avoid issues with creating the Bias voltages and possible issues with the valve heaters. Bias voltage development is now built into the radio.

The reason I refurbed this radio was that my Uncle was RAAF flying for the RAF as a Wireless Operator/Gunner and was killed in a Lancaster over Essen in October 1944 on his 4th sortie.

Thanks for your advice and interest.