[Milsurplus] ARR 15, how to narrow selectivity???

[David Ross]

Mark & the gang -

  There is a detent on the ARR-15 variable IF knob -  that detent 
actuates a switch when the variable IF knob is set to zero (i.e. when 
the variable IF frequency is 500 KCs).  That switch could be used to 
actuate a relay which switches in a 500 KC mechanical filter only when 
the variable IF knob is set to zero.

  That way the variable IF tuning scheme could still be used to 
precisely set the received frequency using the main tuning knob in 
conjunction with the crystal calibrator, but the operator would have 
some real selectivity when the tuning process is complete and the 
variable IF knob is returned to it's "0" position.

  This scheme would probably work OK, but you'll still have the original 
ARR-15 problem -  not enough main tuning bandspread on the upper bands.

Dave Ross    N7EPI



boeing377 at aol.com wrote:
> My Collins R 105A ARR 15 is now working perfectly including the wonderous electromechanical autotune. It is as broad as a barn door however?and I'd like to narrow it wothout butchering the radio. This rcvr has a variable IF as part of the tuning so a fixed freq xtal or mech filter does not seem useful.? I guess I could make a tunable outboard additional IF stage, but that seems extreme. Any practical ideas?
>
> 73
> Mark
> AF6IM
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