Stoner's BC-453 Deluxe Receiver with a 6SN7 product detector.
Multiband Receiver using a BC-453 IF and Stoner's Novice Q5'er, plus a Product Detector
A Deluxe Version of Stoner’s “The Novice Q5-er”
Shelby Hamfest Find.
I purchased this radio at the Shelby Hamfest in 2009 thanks to the encouragement of Nick England and John Poulton. These two guys, Boatanchor enthusiasts to the max, more than any other ham friends are responsible for me owning more military and other boatanchor radios than I ever imagined!
Circuits based on Novice Q5'er and a add-on Product Detector.
Back home I took a close look at the receiver and found a small tag that explains the whole thing. Most of the circuits in this radio is based on the article "The Novice Q5'er" by Don Stoner, W6TNS. The article appeared in CQ Magazine in January 1956. This was good news, because it meant that I had excellent documentation for about 80% of this receiver. The remaining unknown 20% was a circuit that used two 6SN7's. I hoped to figure that out later.
Just recently (December 2014) a fellow ham told me that the two 6SN7's were for a product detector designed by Charles McDowell, W4JJX. His article, "Product Detector for Command Receivers" appeared in QST in December 1956 (p.71). Tube sockets for the 6SN7's were placed on the chassis where the dynamotor was formerly located.
Brought it up on a Variac.
Well ... I brought the receiver up very slowly on a variac. At about 90 volts the receiver came to life. At 100 volts it was working like gang busters. I mean this little radio is hot as a pistol! Who knew?! Tuning is smooth as silk. Selectivity that rivals a R-390A -- well okay, maybe not that good. But still pretty decent. Stable as the rock of gibraltar. The only drawback that I can see is the limited band coverage.
Low Volume Output is a problem to be fixed.
At this point the only function that doesn't work well is the volume control. Audio output is sufficient to run a pair of headphones, but varying the volume control has little or no impact on the level of AF output.
Here's a run down of the system:
1. Band coverage as a funtion of xtals:
Band Xtal Freq convered
1 3010 3.2 to 3.55
2 3500 3.7 to 4.0
3 4310 4.15 to 4.45
4 5630 5.8 to 6.1
5 6900 7.1 to 7.4
2. Tube lineup
6BA6 and 6BE6
The 6 stadard tubes
plus two 6SN7s for the product detector.
Power Supply Chassis
5U4G (5931) + 0B2
3. Front Panel Controls
o Preselector Tuning (80M ................. 40M)
o Band ( 1,2,3,4,5)
o Calibrator (on, off)
o RF Gain
o AM - SSB Switch
o Main Tuning (uses a BC-348 knob)
o LSB - USB (varies the bfo freq)
o BFO (on, off)
o AF volume
o headphone jack
Originally I didn't know what function the 6SN7's provided.
Originally I didn't know the 6SN7's functioned as a product detector. So I wrote the following. I'm guessing they have something to do with the AVC that ties into improving SSB reception? One other triode section might be for 1st stage of AF preamp? Those two fuctions could be provided with one 6SN7, though. Right? Why would the builder put another 6SN7 in the BC-453? Dunno; gotta do some research. You guys have any thoughts on this?
Were you wondering where the 6SN7's were located? Yep, the two 6SN7's sockets were put on the chassis where the dynamotor formerly went.
The builder handled access to the BFO control in a very creative way. To provide top of chassis access (versus original side of chassis access) to the BFO adjustment control, he made two cuts in the chassis on either side of the can, then bent the side of the chassis 90 degrees upward. Neat.
Design and Workmanship of the Original Builder is Superb.
The workmanship in this receiver is outstanding. Whoever built this radio was someone with superior electronic and mechanical skills and knowledge. I can imagine that it took several months to design, fabricate, build, test, and retest and tweak this system. And the result is amazing. After completing it, I bet the builder was damn proud of how well this receiver performs!