[R-390] A 6kc. mechanical filter for a R-390a

[Perry Sandeen]

Yo Dudes, (that’s SO CAL for Hi List)


 
There are several ways to get a 6KHz filter into the R390A.


 
In the Y2KR3 manual (what! You don’t even have a digitalcopy?) Dallas Langford shows how to do it with a new style Collins filter,which is being phased out. About $125.


 
Mouser sells Murata filters for about $5 or sow, but theytoo are not suggested for new design. The same matching data from the Y2KR3 should work OK. Dallas said hiswasn’t exact but worked well.


 
Kiwa sells both ceramic filters that will use the Dallasdata as well as well as active Hi Z modules for $125 IIRC.


 
Last is our favorite high priced source: $urplus $ales ofNeb.  He has ceramic filters that willneed matching as well.  Price is new-bornchild, or in our case, grand-child.


 
There was a Ham who published a note in ER magazine how heused the Murata files in a SP 600.  Iwrote him twice for the matching coil data but he never responded.  Maybe someone else might have better luck.


 
Carpel Tunnel surgery is going to slow me down for 3 or somonths.


 
After I recover I’m re-starting SP 600 re-manning.  I have a supplier for repro dials, and oneworking on a drop in SSB board, and have located a digital dial supplier thatwill have a unit that will replace the logging scale window.  The re-man will also have a Kleonomos (sp) basedP-P class A audio output.


 
Most tubes to be changed to low noise frame grid types.Using a JX-17 chassis I can add A Baxendal (sp) active tone control withindependent bass and treble circuits and a notch filter without having to drilland new holes.


 
When I get one running I will post the details and anyonewho wants a copy of my “Frankinlund” 600 is welcome to the details.


 
Regards,


 
Perrier