[ARC5] ARC type 12 R-11 BFO

[Kenneth G. Gordon]

On 30 Jan 2016 at 11:47, Paddy Ryan wrote:

> BFO in R10/R11
> 
> Jeep I am a little  confused about this. There is no space/dimple in my R11 for
> anything like this...

Well, in my R-11A and R-22 (BC band) there is no space for a regular ARC-5 
BFO coil-box, but in at least one of my receivers there is a sort of "dimple" in 
the outer case where one COULD have been planned at one time. There are 
none of the 4 holes for the mounting screws though.

> also as far as I can remember the detector/avc is used as a
> first audio before the af output

No. That tube, a 14F7 dual triode, has both sections diode-connected (grid 
connected to plate) so that one section is the detector/AVC and the other 
section is the noise-limiter.

I had planned to use that noise-limiter section as the BFO in my 
"ham-mered" R-11A and R-22, and since several of the can-caps in my 
receivers had already been removed, I was then going to install a BFO 
transformer from an R-23 or BC-453 in the receiver and rewire the "other" 
section of the 14F7 as the BFO.

In addition, since my receivers are so well "ham-mered", I have no qualms 
about replacing the main tuning cap with one from a junque BC-453 or R-24, 
adding a dial, and using the receivers.

BTW, I am with David on these receivers: I think they deserve a lot more 
credit than is normally given them. They are really beautifully built and exhibit 
improvements that ARC obviously learned over the years of the ARC-5 
production.

I have only the one R-11A and the one R-22, both (of course) badly 
"ham-mered". :-(

Ken W7EKB