[ARC5] Bandwidth for IF Transformers

[Kenneth G. Gordon]

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