Recepteur Type RI 221

[pwdrive]

2nd part of the reverse engineering exercise, a bit more complex this one, it's for the RF amp grid circuit, I haven't posted a pic of the switch as it's the same construction as that used in the RF amp anode tank circuit, the only difference is that there a two extra contacts and three extra positions.

As can be seen is basically an incremental job using a combination of series antenna capacitance tuning and normal parallel LC tuning, it took me a while to reverse engineer this one, the next will be the 4 pole 3 way lever switch, once that's been done that will be the end of the complicated bit.

   

All RF coils in the receiver showed continuity on ohms range when I tested them.

More to follow.

Lawrence

[AlanBeckett]

Have you considered applying to GCHQ?

Alan

[pwdrive]

Have you considered applying to GCHQ?

Alan

Many many moons ago I applied for a job and got an interview, it was in one of the huts at Bletchley, I failed the interview but I had to sign  the OSA.

Should be able to post the reverse engineering for the last switch later on tonight, a four pole lever switch.

Lawrence.

[AlanBeckett]

Well I'm damned. It was just a Joke based on your ability to work things out.
I went there many moons ago in another lifetime.

Alan

[pwdrive]

3rd part of the reverse engineering, it's for the 4 pole lever switch, not too bad to work out this one, I've not included a circuit overview with this one as I did with the last, it's not really possible 'till the rest of the circuit is done.

In the three parts so far uploaded the component designations I've added might not always make sense but it suits me as things stand, a full schematic will be next with a more logical set of component designations, either in sections or all together if I can get it all on an A4 sheet:

   

Lawrence.

[pwdrive]

There's an error in the schematic in post#15:

L10 (varicoupler) Hot side.

Should read:

L10 (varicoupler) Cold side.

Apologies.

Lawrence.

[pwdrive]

Some more errors ref the drawing in post#15, the switch, it's very stiff and the detent positions aren't too clear feel wise, should have double checked Anyways the corrections are listed below:


CENTER POSITION:

Section "a" The pole makes contact with the lower contact not the upper.

Section "b"  The pole makes contact with the lower contact and should not be in the mid position.

UP POSITION:

Section "b" The pole makes contact contact with the lower contact not the upper.

Section "d" The pole makes contact with the lower contact and should not be in the mid position. Section "d" continued, the letters "nu" should be inserted just to the right of the lower contact.

I won't be posting an amended drawing, I'll sort it all out when I've reverse engineered the rest of the receiver.

Apologies and all.

Lawrence.

[pwdrive]

A quick shuffty at the 4 pole lever switch in conjunction with some reverse engineering of the rest of the circuit is suggesting that this receiver can be operated as a 4 stage...V1..V2..V3..V4, a 3 stage..V1..V2..V3, or a 2 stage..V1..V2.

Either power saving or enabling the receiver to still function if a valve fails maybe.

That's it for tonight.

Lawrence.

[AlanBeckett]

I think that's a good place to stop.
Well done.

Alan

[pwdrive]

Cheers, I've worked out all the circuit now, just got to figure the best way to lay out the schematic on a sheet of A4 so that it makes relatively easy reading, probably go for the receiver set to one particular range with the rest of the ranges, coil configuration wise, on a separate reference sheet.


If the old drawing program I have still functions I might have a go drawing the schematic with it at some point, if I can remember how to use it, the first incarnation is likely to be a hand drawn job with not so straight lines, hopefully it will be proof read by the folks on here to highlight any errors, there's bound to be some

Lawrence.