Rear panel tag
Racal RA-117From the RA-117 manual: 'The Communications Receiver Type RA-117 has been designed for use as a general purpose receiver which will provide a high order of selectivity and stability. The receiver covers a frequency range from 1.0 to 30.0Mc/s... The chassis and major modules are of cast construction thus ensuring maximum rigidity and effective electrical screening.'
The RA-117 is very similar to late RA-17 series (RA-17L) externally, but has important differences in its circuitry, as an added IF stage (it is a four conversion receiver) and lots of tube (valve) and component changes. Anyway, the main characteristics, as the Wadley frequency drift cancelling loop remains. Just as a curiosity, I had the receiver on the workbench for two days before realizing I had a RA-117 instead of a RA-17L...
This receiver is a big one: 10 1/2" Height x 19" Width x 20 1/8" Depth (it is deeper than any of the 19" receivers I have in my shack!). And, consequently, it weights a lot: 62 lb (28 kg). All of this WITHOUT cabinet!. Definitely, not a portable ;-).
Front panel tag
Rear panel tag
MOD record tag
This one is a military unit, as you can see from the front panel tag. Serial number is 0229. And manufacturing date is December 1962, as in the label you can read 'TM' being 'T' year 62 and 'M' December (thanks are due to Robin Filby for this information).
I would like to add a page of RA-17 and RA-117 units information, similar to the one in the R-388(A) pages. So, please, if you own any of these nice receivers, please, let me know.
RA-117 dialTuning is very easy with the RA-117, as you have a big megacycle knob, which electronically (not mechanically, as in most other old receivers, so it is very smooth; think about the R-390(A), R-388(A), SP-600, ... Not so smooth!) selects the 1Mc band you want to work and then you have another big kc knob, which selects, by means of a large film scale (efective lenght is 145 feet, i.e. 6 inches of scale corresponds 100kc/s), the kc component of the desired frequency. Frequency increments remain constant over the entire range of the receiver.
RA-117 kc dial mechanism detail
S-meter
Function selector
BFO control
Bandwidth control
You can select six different IF bandwidths. Filter data is detailed in the table. Wider bandwidths use L/C circuits, and 0.1 and 0.3 kc/s bandwidths are obtained with crystal-lattice filters.
| Position | BW(-6dB) | BW(-66dB) |
| 100c/s | 0.10kc/s | less than 1.5kc/s |
| 300c/s | 0.3kc/s | less than 2kc/s |
| 1.2kc/s | 1.2kc/s | 8kc/s |
| 3kc/s | 3.0kc/s | 15kc/s |
| 6.5kc/s | 6.5kc/s | 22kc/s |
| 13kc/s | 13kc/s | 35kc/s |
RF range
By means of the RF Range control, you can select two wideband (not tuned) inputs at 2000 and 75 Ohm input impedance, and five double-tuned bandpass inputs.
RA-117 top view
If you are familiar to the RA-17 series, here you can see the main differences between them and the RA-117. At the left side of the picture, you have the second VFO unit, which in the RA-117 is smaller, because one previously tuned stage is now fixed. But all the components enclosed in the red line are additions to the RA-117, including the new 1.6Mc/s IF stage and a 2-3Mc/s band pass filter.
Added components and 2nd VFO
In the enclosed zone, you can see lots of coax wiring. These coax go to BNC connectors, and let you select, by doing the proper connections, the use of internal or external reference oscillators and second VFO.
1Mc/S crystal
Rear panel BNC connectors
Another very interesting feature, also found in late RA-17s, is the 1W/3Ohm audio output, instead of the former 50mW/3Ohm. Now the front panel small speaker is more useful and, adding an external common 4Ohm speaker, you have a nice audio output, without any amplifier.