[ARC5] Bandwidth for IF Transformers

[Mike Feher]

Ken -

I have not looked at the manual, so do not know if they show a selectivity
curve, but, from the table you listed I would expect that those numbers are
the total bandwindth nad not half. 73 - Mike 

Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960 

-----Original Message-----
From: ARC5 [mailto:arc5-bounces at mailman.qth.net] On Behalf Of Kenneth G.
Gordon
Sent: Wednesday, March 16, 2016 10:33 PM
To: Bill Cromwell; Phillip Carpenter
Cc: ARC-5 List
Subject: Re: [ARC5] Bandwidth for IF Transformers

On 16 Mar 2016 at 18:12, Bill Cromwell wrote:

> Hi Phillip,
> 
> The specs say the 85 kc cans are (depending on source) 2 kc, 1.5 kc or 
> 1 kc. I saw where somebody reported less than 1 kc. The 2 kc I found 
> in one of the "official' manuals and 1.8 kc in yet another "official"
> manual.

According to the Navy's manual on ARC-5 maintenance, the following
selectivities are listed.

IF Freq.                              Selectivity.

85 KC       1.1 KC at 6 dB down. 4.5 KC at 60 dB down.
239 KC     2.1 KC at 6dB down.  8 KC at 60 dB down.
405 KC     3.2 KC at 6dB down.  13 KC at 60 dB down.
1415 KC   7.3 KC at 6 dB down.  26 KC at 60 dB down.
2830 KC   13 KC at 6 dB down.   56 KC at 60 dB down.

HOWEVER!!!!

Since these figures are the "width" of the selectivity curve measured from
the "nose" of the curve to ONE SIDE ONLY, the actual width of the
selectivity curve is double those figures above.

Furthermore, the Navy manual states that for those two receivers which have
two-position IF coils, i.e., 85 KC and 239 KC, ALL three rods must be pulled
up to their "undercoupled" position before alignment is begun.

I have not yet checked the Army manuals, but I can see no reason they would
be any different.

Ken W7EKB
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