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650B RF and Antenna Tuning Characteristics
etech
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Posts: 237
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City: Gladwin, MI
#1

08-01-2008, 03:07 PM
Hi all,

I have been working on my 650B and have noticed the following characteristics in tuning my radio.


Longwave band.....Antena-Very broad peak.......RF-Sharp peak

Broadcast band.....Antenna- Sharp peak............RF-Very Broad Peak-almost none

Police band............Antenna-Sharp peak.............RF-Sharp peak

Shortwave band....Antenna-Sharp peak.............RF- Sharp peak

I am hoping some of you folks who have a great amount of experience with these 640/650 chassis can weigh in on this. Are the very broad to almost non-existent peaks normal on the broadcast band and the longwave band?

I have noticed that there are two internal capacitors in the rf transformer assembly, caps #16 and #17, associated with the broadcast and police band. I'm not sure of the value of these, but when I measure them with the ohm meter they appear somewhat leaky. Has anyone ever changed these before? What is the value? Could this be the reason for the broad tuning of the rf coil on the broadcast band?

What do you think?

Here is the schematic. http://www.nostalgiaair.org/Resources/824/M0013824.htm

Ed
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#2

08-01-2008, 11:14 PM
Ed and I have been discussing this. Really want to hear others opinions.
-Brian
If you collect or are interested in antique telephones, please visit Classic Rotary Phones
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Ron Ramirez
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City: Ferdinand State, Province, Country: Indiana
#3

08-02-2008, 12:24 AM
Haven't had time to restore my 650B chassis as yet, so I cannot comment on this. Anyone else?
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Ron Ramirez
Ferdinand IN
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BDM
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#4

08-08-2008, 03:15 PM
Anyone at all?
-Brian
If you collect or are interested in antique telephones, please visit Classic Rotary Phones
http://www.classicrotaryphones.com/forum/index.php
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