11-25-2016, 12:46 PM
(11-25-2016, 11:11 AM)ccomer1955 Wrote: I thought I'd check back in on this one. I'm waiting on parts for the other two sets right now, so I returned to the 59. I had a bad power transformer it turned out. I got a replacement power transformer and have installed it. It went well...much easier than I thought it would be, and I learned a good bit about Its doing it. Putting it in, though, I decided to remove the two transformers under the chassis to make room (good idea...it really helped), BUT it turns out the antenna transformer has a bad secondary. The coil itself is dead simple: two windings that share a common ground lug. The one that is bad is the shorter winding on the outside of the primary. The other coil measures out about what it should, so I'm OK there.
I've read here before about rewinding (something else I've never done before), and I remember Ron and others saying that baking the form is a mandatory step. Does that apply to forms that still have the primaries on them? I have some enameled 34 gauge wire here. Will that be thin enough for my purposes?
Hi Charlie,
Methinks you have it a bit backwards. Generally the winding on the left of a transformer is the primary and right side is the secondary on the schematic diagram. Today is your lucky day! The primary is the open one and it's the easier/smaller one to rewind. There is no particular phase relationship to the two winding so direction is not all that critical. Also it's not a tuned circuit so the # of turns are super critical. The secondary is.
> Does that apply to forms that still have the secondaries on them?
Yes, If you are of that mindset. The idea is to evaporate any moisture absorbed in the coil form, the moisture can have an effect on the efficiency of rf transformer. I would think that it is more critical for the osc transformer. This efficiency is known this the "Q" of the coil or transformer
> I have some enameled 34 gauge wire here. Will that be thin enough for my purposes?
Yup your good. But don't use the original resistance as a gauge to determine # of turns. The larger wire will have a lower resistance hence you would be prone to more turns to achieve to "correct resistance". Here if you count the turns that is the best if not just wind enough turns to fill the original space and add a few more for good luck.
PT's aren't difficult to replace if you can find a replacement that meets the physical and electrical requirements. Most have a known color code for the wires which save alot of guesswork. Some of the oem units don't conform to the RMA standard color code.
Mike types much faster than I!!!
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Terry