[ARC5] BC-453/Q5er Converter

[WA5CAB at cs.com]

Henry,

OK.

The R-23, like the other 190-550 KC receivers, was used to receiver 500 KC 
and more normally the MF transmitters at various airfields.  Remember that 
until the shift to VHF the common practice what that plane to ground was HF 
and ground to plane MF.  Plus the R-23 could be hooked to a manual loop for 
manual DF.

As someone else already wrote this morning, the antenna input impedance of 
all of the Command Set receivers (except the R-28) was quite high.  In all 
of them (except R-28) the antenna post is connected to the input tuned 
circuit through capacitor C-1.  In the BC-453 and equivalent, C-1 is 11 uufd.  The 
capacitive reactance of C-1 at 550 KC is about 26K ohms.  This feeds a 
parallel resonant circuit in parallel with the grid of the 12SK7 RF Amp 
(actually the grid is tapped down on the coil).  The grid is 2 Meg above ground for 
RF.  Anyway, compared to the impedance of any available coaxial cable the 
net impedance is "high".  The higher frequency receivers have slightly smaller 
C-1's.

In a message dated 9/26/2010 11:01:23 AM Central Daylight Time, 
meils at get2net.dk writes: 
> Robert,
> 
> My  .19-.55 MC ARC-5  receiver was at the bottom of a stack of ARC-5 
> receivers, so I didn't
> look at it's designation before I mentioned it. Now I dug it out and 
> you're 
> right.
> 
> It's an "R-23/ARC-5
>            NOs 74912  6657 CBY".
> 
> Now that I've precisely identified my unit, maybe you can tell me 
> something 
> about its history.
> I could post the ID's of the my other identifiable Command Set units, some 
> 
> other time.
> 
> I was just using the term 'BC-453' loosely as a kind of generic reference.
> But what is the aprox. ant .input Z of the Command set receiver series?
> 
> Henry M, Cph.
> 
> ----- Original Message ----- 
> From: <WA5CAB at cs.com>
> To: <arc5 at mailman.qth.net>
> Sent: Sunday, September 26, 2010 4:33 PM
> Subject: Re: [ARC5] BC-453/Q5er Converter
> 
> 
> >Henry,
> >
> >According to the manuals and the dozens of BC-453's I've had or seen, the
> >BC-453 never came with Loop input.  Your receiver with it is probably an
> >R-23/ARC-5 (or R-148/ARC-5X).
> >
> >In a message dated 9/26/2010 1:07:58 AM Central Daylight Time,
> >meils at get2net.dk writes:
> >>But the BC-453 could also be used with a loop: I have one unit with an 
> "A
> >>L"
> >>switch)
> >>
> 

Robert & Susan Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480