[R-390] 4 kc filter

[Biddle, Richard]

I have seen these options:

Buy a spare deck and hope. 

Get a new Longwave Products 5 kc replacement mechanical filter.  These go
for $200/each for the Collins 75A4.  (Chuck Ripple has details.)   Then you
can restart the 50 year wear-out clock :)

Use an R-390 IF deck in an R-390A.

Has anyone tried replacing a single mechanical filter with a readily
available crystal filter, preferably one that does not cost an arm and a
leg?  

I wound up with two spare IF decks - one Collins and one Motorola.  I had
hoped to swap for a Dittmore-Freimuth 1968 DAAB05-68-C-0040 IF deck in good
non-hacked condition.  Then all I will need is a matching contract power
supply and all the modules will match.  I know it doesn't matter and I'm not
too worried about it, but I think any radio I keep in an oak case deserves
it.   

73 de Richard, KB5WLH