Restoring an R1155 Receiver (/cont.)

As well as letting a couple of R1155s go over the last 35 years, I also have to confess to throwing out a box of Octal valves, many of which were no doubt ex-R1155! We live and learn. Spares for these receivers are not as unobtainable as you might imagine. Ebay can be an excellent source of parts, with sellers frequently advertising valves specifically for the R1155 ... But beware! Often those advertised are NOT actually suitable. The KTW63 (aka 6K7) for instance may be pin-for-pin compatible with the KTW61 or 62 but exhibits far less gain, so should be avoided. This is not to say that these sellers are deliberately trying to deceive you. It is possible that they themselves found such valves already installed and assumed that they were compatible. For example, I recently found a 6Q7 in the BFO compartment of an R1155, where an MHLD6 (or VR101) should be fitted. In this case the 6Q7 is almost acceptable however it is questionable if the same substitution could be made for V8.

So, how does the re-built A.D.8882B perform? Absolutely fantastic! There’s no other way to describe it. Far better than I remember any ‘original condition’ set performing. For AM reception, it is best to have the Master Switch at the  AVC position (position 2). It is too often said that the 1155 is no good for SSB reception. For SSB and CW it is recommended to set the Master Switch to position 1 which disables the AVC. I then tuned the BFO for best audio from a 40m LSB signal. Resolved LSB on 40m and 80m is superb! During the day, I use the A.D.8882B for listen to the local AM broadcast station.

R1155 Valves and Equivalents ...

V1, V2 ......... VR.99A, CV1581, ECH35A

V4 ............... VR.99, CV1099, X66

V3, V5, V6 ... VR.100, CV1100, KTW61, KTW62

V7, V8 ......... VR.101, CV1101, MHLD6, DL63

V9 ............... VR.102, CV1102, BL63

V10 .............. VI.103, CV1103, Y61, Y63, 6G5, 6U5, EM34

The R1155 heater supply was actually DC and I have heard it said that an AC source should not be used since the set was not wired for AC. However this is not the case. An AC heater supply is perfectly suitable. The reason why the original heater supply was DC is simple; Power on the aircraft was provided by a ‘dynamotor’ which is ONLY capable of providing DC.

Another frequent error often made or suggested is to internally connect together the Fixed and Trailing Aerial inputs. This may simplify the RF input to some degree but is not advised since the two inputs are independently matched by separate transformers. Input switching in the R1155 is achieved by a combination of Master-Switch and Range Switch settings with the Fixed Aerial input being selected on ranges 1 and 2 and the Trailing Aerial for ranges 3 to 5.

Left ... A small sample of the wiring removed from the A.D.8882B