Hello from eastern NC, joined the phorum today and have spent a good bit of time reading everything I could find about the 49-900-121 model. What I haven't been able to find is where the 4 leads from the loop ant connect. Here's a pic for reference purposes. I think I attached correctly. Thanks and I look forward to some guidance.
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Hi and welcome,
To answer your question it looks like one of the wires is still connected, the one the tuning capacitor. The other end of that wire connects to the chassis. Now you should have 2 left. One connects to a .0015 mf/1500pf to the chassis. Other end goes to the external antenna terminal on the back of the set. Don't think the phasing maters (which end is which).
https://philcoradio.com/library/download...8-1949.pdf
GL
You can think of the antenna loop as a rf transformer with a tuned secondary. One end of the primary can be connected to an external antenna to feed a stronger signal to the primary. The other end is grounded through a capacitor. One end of the secondary is usually connected to the large section of the tuning capacitor and also the control grid of the first tube. The other end of the secondary is usually connected to the AVC line in order to feed AVC to the grid. The variable tuning capacitor will set up a resonance at the desired radio frequency. You can determine the primary by finding the connection to the capacitor and measure continuity with one of the other connections. Should be less than one ohm. The other two connections are the secondary. This is very important to get correct because it affects signal strength.
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Schematics often have some form of diagrammatic to the symbols not only as a draftsman's short-cut but to inform the reader of certain characteristics of a component. This loop is no exception. The drawing indicated there is no direct connection to the AVC. It does indicate with end is which by virtue of connections to the inside or start of the winding and outside or finish. These connections should be observed as the secondary is tapped and reversing connections of the tap would hinder performance. If the windings have been peeled back and possibly shortened that too will effect reception... It is most important that the secondary not be shortened.
If you are still unclear, I have two examples of this radio in my collection that I can access and take images... chas
I marked up your image to indicate where the connections go.
The connections are intact on my radio but the tangle of fine wires in a photo makes it impossible to interpret.
There "should" be some black paint on the secondary wires and the primary wires are "mostly" white.
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I do not think that "polarity" of the secondary matters, but, there is still one end attached so your good... chas
Thank Chas, this is very helpful. Hope you got the snow shoveled without too much difficulty. Very much appreciate your willingness to help a newbie. Take care and stay warm. Spring is just around the corner.
Rob
Rob,
Yes, the 45yo Ariens snow blower is still chugging along. The reason I had to get to the snow was a prediction of rain then freeze. My 2020 Camry is low ground clearance and frozen ridges of ice can cause a problem, it is a lease... More rain is predicted today, long range forecast looks good so far, Probably have a cool early Spring, but me bones say it will be a nice Summer coming early...
Thanks for the feedback.
Sure is a shoddy arrangement for the antenna, The tech will have to use a substitute antenna for live bench work...
I'm glad I got both of my Hippo's cheap, the other one is a slightly different chassis in painted ivory, a couple of chips...
Hope you enjoy radio collecting. My thing is don't buy busted, rusted or missing bits and as cheap as I can...
The last wooden table AA5 was two years ago, at the right price of $10, untouched in modern times, finish nicely alligatored.... chas.