Help with R1116 receiver

[Peter F]

Hello,
I'm in the process of restoring a R1116 receiver and while it's starting to work, I have no reference data to check it against.
Audio output seems low and many of the anode and screen grid voltages also seem low, in the order of 30-40 V. The set uses directly heated valves with an HT of 120v.

What would be most helpful are alignment data and typical voltages if anyone can help please.

Peter

[wireful3]

Hello Peter, I had one of these sets many many years ago and though I have no alignment data, there is one important thing to remember if you are not already aware and that is that it is a double superhet, so has two IF frequencies. One I think was about 110kHz the other about 465kHz. There might also have been some switching that changed the IF arrangement between the two groups of frequency bands. Mechanically I remember the IF adjustments had locking collars.

I can't remember any of the voltages but the anode voltages do seem a bit low. I don't know what power unit you are using but it has a lot of valves for a battery set so they maybe loading the supply. The audio output is intended for phones but I am not sure whether this was for 600 ohm or 2000 ohm. I think in use it was intended to work into a two valve intercom amplifier so the output may not have been all that great.

One thing that stays in my memory is that the sensitivity was exceptional for a battery set at the time.

[JohnBradford]

Hi Peter,

I’ve more or less finished rebuilding an R1116 with new components (it was something of a basket case, someone in the past had already rebuilt it with octal valves and leaky capacitors), these are the voltages I measured:

V2 mixer anode 102v, oscillator anode 28v, screen 65v
V3 anode 102v, screen 56v
V4 mixer anode 102v, oscillator anode 28v, screen 31v
V5 anode 102v, screen 59v
V6 anode 87v
V7 anodes 91v, screen 91v
V8 anode 97v

Control settings – CW, volume control fully clockwise.

Take these measurements with a pinch of salt as the HT was only 103v (limited by the power supply), I’m not sure its working properly yet and the output transformer is not the correct one.

The first IF is 1700kHz and the second IF is 100kHz; I found this a bit tricky to adjust as the bandwidth is quite narrow. The second LO is 1600kHz.

Do you have the manual for this? I can send you a copy if you need it.

John

[Peter F]

Hi John & John
Thank you both for your responses.

John (wireful3). I was not aware that the designed output impedance was high, this may account way I see such a low output level, I’m feeding a low impedance set of headphones. Also the use the intercom amplifier would also mean that a high output level would not be needed.

John (JohnBradford) I guess a lot of this old set have been modified over time, trying to put them back as original can be hard work.
Thanks for the voltages. I was rather concerned when measuring only 31v on V2 oscillator anode and 60v on the mixer screen, your measurements are reassuring. I’m working from the output toward the aerial, just got as far as the 2nd mixer, the other measurments will help a I move forward.

I don’t have a manual just a circuit and some articles from Radio Bygones. If you could send me a copy of the manual that would be great.

Peter

[wireful3]

Peter. As far as the phones are concerned I think at the time I used 2,000 ohm phones but I might have had some of 600 ohm impedance. It is many years ago so it is only a hazy recollection.

Perhaps you could refresh my memory but I think it did not use a tuning capacitor but had sets of iron cores on a yoke that moved on a lead screw. I guessed this was to keep a good L/C ratio for high Q. I suppose it might also have been less subject to vibration.

I don't know what the power supply would have been but I remember using a multi-pin connector with flying leads for a dry HT battery and a lead acid accumulator. It was obviously intended to connect to a wiring loom in the aircraft. I can't imagine this was used in practice but it left me with the whimsical thought of an airman taking the accumulator to the local cycle shop for recharging, like many people did in the mid 1930s

[Peter F]

John
You’re correct, this set is permeability tuned. The coil cores are moved by a very smoothly working screw thread and gear mechanism. I’m knowledgeable enough to comment on the advantages of this arrangement over using a variable capacitor, but your suggestions sound reasonable.

As for the power requirements, it uses HT at 120v LT at 2V connected via a 4 pin W type connector there is also a bias battery to bias the directly heated valves, this is internal, I guess the current drain is very low so it doesn’t need changing often.
Peter