[Drake] Early R-4B?

[Bob Camp]

Hi

This sounds an awful lot like a radio made from R-4 parts rather than 
an R-4 ....

	Take Care!

		Bob Camp
		KB8TQ


On Jan 9, 2005, at 1:38 AM, w7fe wrote:

> To those familiar with the R-4B:
>
> I recently acquired a somewhat corroded but working R-4B.  During my 
> initial inspection and subsequent cleaning and repair process, I've 
> run across some rather puzzling things:
>
> 1.  This one has no chassis markings at all, not even a serial number. 
> There is enough of the original copper plating left to indicate that 
> no markings had ever been applied.  There are no silk-screened 
> switch/jack/pot i.d. markings on the case exterior either. Unusual?
>
> 2. The passband tuning/selector assembly is not as described in the 
> alignment procedure or as pictured in the manual.  The passband tuning 
> shaft is connected to a little butterfly variable capacitor, not to a 
> mechanism to vary the position of the slugs in the coils.  This is 
> visible because there is no can over the passband tuning circuitry, 
> just a u-shaped mounting bracket, open on the right and left sides.  
> The passband selector is actually a rotary switch, with a lot more 
> components around it than are shown on the schematic. Does this 
> perhaps suggest a very early model, maybe before they developed the 
> mechanism to tune the coil slugs and simplified the circuit for 
> passband selection?
>
> 3. L6 in the output filter on the PTO is not present at all. The 
> center conductor of the co-ax (which goes to the xtal-vfo slide 
> switch) is just lap-soldered to an unshielded wire which comes from 
> the PTO output.   C132 and C149 are in place (on the nearby audio 
> board), however.  I can see where L6, the co-ax, and the PTO output 
> lead should probably have been connected on the adjacent audio board, 
> but it appears that nothing has ever been connected to those points. 
> Does anyone know what value L6 should be, or its physical 
> characteristics?
>
> 4. There is a black/white wire coming from the PTO and connecting to 
> nothing.  This must be the FSK connection as per the schematic, but 
> it's just flying free.  Should it connect somewhere, like to one of 
> the lugs on the adjacent audio board?
>
> 5. Generally, many of the solder joints are poor, some cold, most with 
> excess solder, and several places exhibit wire insulation which has 
> been melted by an errant iron.  The wire harnessing and lead dress are 
> quite sloppy; in fact, there are wires attached to the filament pins 
> on V2's socket which have been clipped off to about 1/4" and left in 
> place, connecting to nothing. Also, there is a wire attached to a 
> ground point near V8's socket (which is the same color as V8's 
> filament lead which connects at an adjacent terminal point) which is 
> clipped off to about 1" and goes nowhere. Is this lack of  good 
> workmanship  weird, or what?
>
> 6. Finally, another goofy observation for those who have were 
> interested enough to read this far:
>
> The brass shaft coupling to the passsband selector switch shaft was 
> cracked and split!  I'm baffled as to how this might have happened. It 
> looks almost as if water got into it and froze, splitting the 
> coupling.  Has anyone seen this condition before?  Anyway, it results 
> in unacceptable excess play in the little lever actuator for the 
> passband selector. Now that I have removed the coupling (in several 
> pieces), I think that they used 5/16 OD brass tubing, with a little 
> flat spring wedged inside to produce a tight connection between the 
> two shafts...looks fixable with some hardware store tubing. Has anyone 
> else had occasion to do this repair?
>
> 73 de Stu   W7FE
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