Gregg, I don't know why the ratio was changed in the first place, but I really don't think it will make much difference in the signal level. You can try re-winding it and see what happens. The biggest difference should be in the termination impedance of the filter.
The 20/5 transformer has a turns ratio of 4 which is an impedance step-up of 16; while the 11/3 is a 3.67 turns ratio or an impedance ratio of 13.44, so do compare the before/after CW filter passband ripple at wide filter settings - where I would expect the major difference to be seen. If you do try the new winding ratio, please let us know the before/after results if you can quantify it with a fixed signal input level. As an aside - if the KNB2 is installed, check to see if the -5 dB pad was removed (R88 and R90 not installed and R89 replaced with a jumper. 73, Don W3FPR ----- Original Message ----- I'm working on a Rev A board and noticed that on the coupling transformer to the IF amp that it is built different than the Rev B models. On this one the Red (3/4) windings are 11 and the Green (1/2) windings are 3 On the Rev B the Red (3/4) windings are 20 and the Green (1/2) windings are 5. My question is now that I've made all the upgrades to Rev B and am having problems in this area of the circuit (ie: low sensitivity and all the stages prior are working properly), should I rebuild this torroid?? _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
