Rf transformer replacement - Printable Version
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Rf transformer replacement - tab10672 - 06-11-2013
Hello, I am working on an aa5 that is missing one of the rf transformers, the original should measure 16/16 ohms but the closest I have found measures 17/19 ohms would I be able to align the replacement to work? If not, can a capacitor be added across the coils to tune in the correct freq.? Thanks, Todd
RE: Rf transformer replacement - Arran - 06-11-2013
What model and what year?
Regards
Arran
RE: Rf transformer replacement - tab10672 - 06-11-2013
52-542
RE: Rf transformer replacement - exray - 06-12-2013
I guess you mean IF transformer? No RF xfmrs in that set.
The first IF is pretty generic. Note that the second one has the 'scrubber' components (R6+ two caps) mounted inside the xfmr. That's common too in 1950s sets but note that it is not your standard 4 connection can.
You can mount the R6 and two disc caps (100-150pf) externally if need be.
Otherwise, don't be concerned over the DC resistance of the coils. That has no impact on the circuit. If your replacement is of the same general type from that era you can pretty much count on it being the same frequency (455kc).
RE: Rf transformer replacement - tab10672 - 06-12-2013
Yes, I-f. So as long as it is a 455 can the resistance no matter how high or low is not a factor? Also I added the 2-120pf and resistor as in the schematic. Now I can adjust it in at 455 with my sig. Gen. But when I try to adjust the 1500/1600 on the tuning cap through the loop ant. as per alignment data. The only way I can pick up the sig gen is at the lowest end (fully meshed) no matter what freq is on the gen. Would polarity be an issue? The dot is always no.1 terminal right?