[ARC5] BC-453/Q5er Converter

WA5CAB at cs.com WA5CAB at cs.com
Sun Sep 26 14:11:16 EDT 2010


I haven't checked the RF coil rack pinouts but would suspect that you could 
plug an R-23 or R-23A coil set into an early BC-453 or an ARA (late BC-453 
production doesn't have all of the pins present).  Unfortunately, neither 
the AN/ARC-5 nor RAV manuals give RF coil winding information.

In a message dated 9/26/2010 12:36:35 PM Central Daylight Time, 
meils at get2net.dk writes: 
> Thanks.
> 
> Was wondering if winding a link around the input coil would be worth the 
> trouble.
> 
> An external matching network would probably win a few dB if the feed-in is 
> a
> a 50 ohm line. I've built a couple of external  Z-match pre-tuners for
> my Hi-Z input receivers - they can also be used for QRP transmitters.
> 
> 
> ----- Original Message ----- 
> From: <WA5CAB at cs.com>
> To: <arc5 at mailman.qth.net>
> Sent: Sunday, September 26, 2010 6:30 PM
> Subject: Re: [ARC5] BC-453/Q5er Converter
> 
> 
> >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


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