[ARC5] Fwd: Re: [MRCA] SCR-274-N receiver bandwidth spec

[D. Platt]

-------- Original Message --------
Subject: 	Re: [MRCA] SCR-274-N receiver bandwidth spec
Date: 	Sun, 23 Mar 2014 14:09:02 -0400
From: 	D. Platt <jeepp at comcast.net>
Reply-To: 	jeepp at comcast.net
To: 	Military Radio Collectors Association <mrca at mailman.qth.net>



Yes, the washer is metallic (Al) and has a "pan handle" that attaches to
one of the vertical leads. I'm assuming its the ground lead, as all the
coils are buttoned up, just now.

Jeep

On 3/23/2014 1:32 PM, J. Forster wrote:
> If the washer is metalic, even brass or aluminum, it will decrease the
> mutual inductance between the coils, thus narrowing the 'rabbit ears'
> response curve or narrowing the BW.
>
> -John
>
> ===============
>
>
>> Gentlemen,
>>
>> Continuimg with my ARC-5/SCR-274-N receiver IF coil mod investigation, I
>> just completed yet another coil set, this one from an ARC-5/R-26.  In
>> doing so, I find yet another mechanical set-up in these coils.  This one
>> has the long brass screw (up from the bottom) and threading into the
>> phenolic spacer bar (vice using a nut).  All else is the same as other
>> coil sets and I find that coils sets are, so far,  interchangeable.  The
>> question for today is what is the original published (sic) receiver
>> bandwidth of this receiver?  I'd like to know what the starting point
>> should be, even though I'll be measuring unmodified and modified sets.
>> At this point, I can again say that there /is/ a detectable improvement
>> in selectivity.  What remains is to quantify things and, as we speak,
>> I'm proceeding with the procurement of a suitable sweeper.
>>
>> Another point of possible interest is the fact that in each and every
>> coil set there appears a 1/2" disk "shield" positioned between the upper
>> and lower coil bobbins.  Could this be what others have spoken of as a
>> method of providing electrical separation (read: increased selectivity)
>> between these coils?  If so, then someone back then was thinking.........
>>
>> Regards    Jeep - K3HVG
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>
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