RECEIVER MARCONI R1155
OVERVIEW
History
On order from the Air Ministry (AM), Marconi Wireless Telegraph Company in 1939 started the development of a transmitter/receiver
system, the T1154/R1155, based on the AD77/AD6872 which was used in passenger aircraft. By that time Marconi was the leading
manufacturer of aircraft radio in England and perhaps in the world. The system was intended for use in heavier military aircraft, and during
the second world war it was used in light bombers like the Blenheim and Mosquito, and in heavy bombers like the Stirling, the Halifax
and above all the famous Avro Lancaster.In the beginning of 1940 the Ministry of Aircraft Production (MAP), accepts the design and the first production set is installed and tested in june that year. Marconi has the overall technical responsibility and E K Cole (Ekco) is responsible for the production. Plessey, EMI and others are also producing in addition to Marconi and Ekco.
On the 8th of June 1941 the Costal Command issues a report to Marconi on serious interference from Radio Athlone in Ireland on the frequency 565 kHz, which is close to the R1155 IF. On the 12th of August Marconi reports to MAP saying that an investigation has started. Three IF traps are designed and added to an R1155 model 10D/98. The receiver is flown to Ireland for testing with a positive result. Ekco is ordered to issue a specification for the change and it is decided that the IF traps are to be added to all R1155´s from now on to avoid interference problems. Some earlier receivers are also modified with the filters and the new model number is R1155A 10D/820. Later other filters are added to avoid interference from the radar.
In July 1941 problems with the tuning knob type 13 are reported to Marconi. The coarse tuning is moving with the fine tuning because of unsuitable friction and because the operators are wearing thick gloves against the cold. In Januari 1942 Ekco delivers a new type of tuning device designated type 35, which is approved by the MAP. The new type has probably been used in production the second half of 1942 and it was also retrofitted in some of the older receivers. It seems that not all the old receivers were modified, and not even all the new ones got the type 35 tuning knob.
The R1155 was manufactured as models R1155, R1155A, B, C, D, E, F and L, M, N. Of these models R1155, R1155A, B, C, D, E and F were intended for use in aircraft. Model R1155 had no filters, A had the IF traps added and B also had the radar filters. D, E and F were the corresponding receivers with steal case instead of aluminium. C was a model with direction finding circuits working on HF, was taken out of production early, and L, M and N were used in ground stations and vehicles, and in sea vessels for the Coastal Command.
When the war finally ended more then 80.000 R1155´s had been delivered!
Receiver Data
The R1155 is a single super with one HF stage and oscillator/mixer, a total of three tuned circuits, and two IF stages. With detector, BFO and AF stages there is a total of 6 valves plus a magic eye as tuning indicator. There are facilities for direction finding and homing and the D/F part has 3 valves, see the block diagram below. The set covers 75 to 1500 kHz LF/MF in two bands and 3 to 18.5 MHz HF in three bands. Bandwidth is 5 kHz @-6 dB and the sensitivity is better than 10 uV on all bands. Although rather simple the receiver has a remarkably good performance for short and medium wave world radio listening.
My Receiver
Model Number Serial Number Remarks
(REF No) (Serial No)
Receiver 10D/98 32343 AM Crown
modif. to 10D/820
alu case for receiver 10D/308 Marked inside back
Indicator 10Q/2 733529 SW/R/45
(made1945)
servised by MOD and repacked in 1965
Morse Key 10F/7741 Type F House 10A/7741 Knob 10A/7790 Knobs 10A/7789
Phones 10A/12161 Case 10A/13466
Plug 10H/735
and 10H/10991
Suppose the production started on a small scale in the middle of 1940 and reached full production rate in the end of 1942. Suppose that some 10.000 receivers had been produced until 4205. The remaining 70.000 were then built in three years until 4505. If the production rate was now linear my serial number would have been built around 4305 or probably a little later, that is the second half of 1943. It is also possible that different producers had their own number series so that the receivers were not produced in serial number order. (Dave Kemplen has in his article in Radio Bygones stated that his receiver with serial 3051 was built as late as August 1942, which could indicate either that or a slow start of production). There also are receivers with very high serial numbers around 100.000 and with a B before the number.
It is a bit odd that my receiver which was manufactured as model R1155 10D/98 and has the tuning type 13 has such a high serial number, but after all it was war and there might not have been resources to build enough filters and tuning devices type 35. My receiver has never had the fine tuning scale around the knob, there are no holes drilled for it, it was removed on later R1155´s. Probably receivers with both tuning types were manufactured in parallell for some time. My receiver also has a colored scale, late receivers had black markings. Despite contradicting facts my guess is that my receiver was manufactured in 1943.
A round stamp with the letters/figures MWT 164 and a figure stamp 1488 indicates that the receiver was modified and checked by the Marconi Wireless Telegraph Co (MWTC).
Literature
Ref 1 Manual A.P.2548A vol I chapter 2 (see link on main page)
Ref 2 Lancaster bomber with receiver R1155 (my collage, refer to the photo gallery)
Ref 3 Radio Goes to War and a Legend is Born (by Chas A. Miller, Radio Bygones nr 1)
Ref 4 Rebuilding an R1155 (Dave Kemplen, Radio Bygones nr 59)
Ref 5 Articles and letters from readers in Radio Bygones, see RB master index
More on WWII receivers
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Updated October 14th 2009