RCA Victor 11Q4 motor tune radio.

[Geordie McBoyne]

Last month I brought this American made set over from France, donated to me by Radiofil member Wilfrid (wiwior)

Pictures of the chassis, in terms of construction quality it resembles a pre-war HMV radio.  I guess the reason for that was because EMI was an RCA affiliate.

Geordie McBoyne.

[Geordie McBoyne]

From the Radiomuseum. A picture of the cabinet, the valve compliment and other details.   This receiver should be an excellent performer because it has an RF amplifier stage and two IF stages.   The metal valves are quite compact, in fact only slightly larger than the all glass B9A types introduced only ten years later in 1948.

http://www.radiomuseum.org/r/rca_11q4.html

The frequency changer consists of a 6L7 hexode and a separate local oscillator using a 6J7 triode pentode connected as a triode.

Geordie McBoyne.

[Mike Watterson]

The frequency changer consists of a 6L7 hexode and a separate local oscillator using a 6J7 triode pentode connected as a triode.

That's a higher quality method than the Heptode or Octode method that became popular in USA mains sets.

Victor Talking Machine Co. founded HMV.
When HMV became separate and took over UK branch of Colombia (Graphophone, the USA part became CBS eventually), that  became EMI and took over Marconi Domestic radios with a licence to use Marconi brand.

Victor also founded Victor Japan, later known as JVC.

Marconi was forced (as a foreigner) to divest RCA which bought Victor.

Hence RCA, EMI (HMV) and JVC had right to the Nipper & Gramophone logo, ironically originally painted with an Edison Phonograph, in different markets.

EMI, Marconi (the Commercial radio company rather than the domestic Brand) and RCA cross licensed and co-operated for many years after ownership was separate, hence the EMI/RCA camera & TV co-operation and Marconi Transmitters. 

The 1928 to prewar EMI (HMV/Columbia/Marconi brands with the same chassis) often were high quality. One 1949 model HMV I have had almost usable paper dielectric capacitors, the slatted glass scale copied a 1930s Telefunken, who I believe did take RCA patent licences in the early 1930s?

Sadly RCA ended in 1986.

Lucky you having one of those high quality RCA models!

[Geordie McBoyne]

...and in France:  la voix de son maitre

Geordie McBoyne.

[Geordie McBoyne]

Making a start of the electrical restoration.  As you would expect from a receiver of this vintage almost all the paper dielectric capacitors are leaky.
I don't like the look of those yellow hi-viz replacements in vintage sets so I've restuffed almost all of the original tubular paper capacitors.  
The HT electrolytics will need reforming. These are not the originals and the smoothing components in place now are the Continental "Micro" make.

Geordie McBoyne.

[Crackle]

Why has the back of the tuning cap drive drum/wheel got scale markings on?

Mike

[Geordie McBoyne]

The alignment instructions inform us that because the tuning scale is fitted on the cabinet and cannot be used as a reference during alignment a calibration scale is attached to the tuning drum.

The schematic for the RCA 11Q4 (RC335C chassis)
https://www.tubesandmore.com/schematics/...o-inc/11q4

Geordie McBoyne.

[Terry]

Could it be that alignment can only be carried out with the chassis separated from the tuning scale and pointer? When the set is reassembled it only requires the pointer to be set to one calibration mark on the scale for the whole lot to fall in place.

[Geordie McBoyne]

Full alignment of this receiver can only be accomplished when the chassis is removed from the cabinet.
You've got to careful removing the chassis from the cabinet and must remember first to unclip the  tuning drive cord from the scale pointer.
After refitting the chassis the scale pointer will be refitted to the cord and a simple adjustment made to make sure calibration is correct.  Use either a radio station of known frequency or better still inject a signal of 1500Kc/s.

Geordie McBoyne.

[Geordie McBoyne]

Todays big news is that the set works.   As you would expect from a receiver that has an RF amplifier and a two IF amplifier stages sensitivity and selectivity is excellent. Plenty audio power thanks to a pair of 6F6G pentodes.  The HT rectifier valve is the unusual metal type 5T4, the example in this set is rather rusty. The 20µF HT reservoir capacitor was found to be useless so for the time being a wire ended electrolytic will be used.   A proper can electrolytic is available from the BVWS shop.
However,  after a few minutes of use the audio faded away, the 200 volt HT supply dropped to less than 50 volts, the fault turned out to be a almost hidden 0.25µF capacitor going leaky, wax could seen oozing from out of the capacitor ends.  It's been clipped out.
The motorised tuning system also works as it should.  There are still plenty jobs to do to this set.

Geordie McBoyne.