[ARC5] BC-453/Q5er Converter

[Henry Mei'l's]

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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