[HBR] JW Miller IF transformers

[Sandy and Kees Talen]

You have probably followed some of the information on converting
JW Miller (and others) K-Tran 262Khz IFs to 100Khz for use in the 
smaller HBR units. These are like the #1710 transformers.

I received some JW Miller 262Khz #90-PHP transformers which 
are identical electrically to the JW Miller 262Khz #15-H transformers 
I tested earlier. Only difference is 2 extra pins for detector filter 
capacitors (not used) and the shield has PC board mounting, not 
the K-Tran clip and the can will need to be grounded. These 
transformers are available from  JMarsh1014@aol.com  I believe 
he has a qty of them and maybe some others. You can contact 
him directly.

Just use pins 1,2,3,and 4, add a 430pf SM padder capacitor and 
adjust the powdered iron cap all the way in and back it out 1-1/2 turns. 
Makes a good 100Khz transformer very much like the JW Miller 
#1710. The spectrum analyzer plots are close.....the #1710 being
slightly better. If you put two in series the passband is excellent with 
steep skirts (at -20dB it's only 10Khz wide). A single #1710 is about
15-18Khz wide at -20dB. 

I'm trying a few other things like substituting two coils in series to
increase Q and I've seen some improvement but I don't think the 
extra work is worth the improvement .......it's nothing like using
two IF transformers in series.

73s  Kees K5BCQ