[Milsurplus] Motor tuned ARR-2 ?

[MICHAEL BITTNER]

One of the things I found most intriguing about the ARR-2 circuitry is its reactance controlled BFO pitch control.  How can you control the frequency of this high-Z LC circuit through cables from a distantly located control box?  Most remote-controlled receivers don't even attempt it and leave the BFO frequency fixed with just an on/off switch, e.g. ARC-5.  The ARR-2's answer is a reactance tube across the BFO's LC tank with a rheostat in its cathode return to ground, said rheostat located in the control box.  This Low-Z cable connection is unaffected by variations in cable length and is an elegant solution to the problem.  

I think there is one ham-band receiver that also uses a reactance tube for BFO control but not for remote control but simply to allow placing the control at a desired location on the front panel without having to use some awkward arrangement of shafts/gears/belts/pulleys/string/whatever to connect the control knob to a variable L or C in the BFO's location elsewhere on the chassis.  Just a couple of hookup wires will do.  I'm not sure which receiver this is.  Does anyone else know?   Mike, W6MAB



> On May 6, 2022 at 9:39 AM Jack Antonio <scr287 at att.net> wrote:
> 
> 
> I agree that the ARR-2, and its predecessors the ZB and ARR-1 do not 
> have any current
> practical use.
> 
> But it was interesting to fire them up, in a stock configuration, and 
> use the
> test sets to provide a signal for them.
> 
> I have two of the ARR-2 receivers, and both of them came up very easily,
> the biggest issue was to get the BCB frequencies lined up between the
> receivers and the test sets.
> 
> And yes, I did use the original 246 (+/-) frequencies, but I padded the
> output of the test oscillators way down to barely above leakage.
> 
> The test sets generate an unmodulated CW signal, I thought about
> building up a small morse keyer so they would simulate an actual
> transmission, but its probably one of those things that will never get done.
> 
> Jack Antonio
> WA7DIA
> 
> 
> 
> On 5/5/2022 5:15 PM, W2HX wrote:
> >
> > I saw that too! Very nice little package. Too bad its not more useful. 
> > But very nice