firestone: Firestone Firechief S-7428-2 antenna

I am restoring a Firestone Firechief S-7428-2 MW radio. The schematic reflects a loop antenna or a long wire antenna. The unit I am working on is reflective a long wire antenna. My question is; the schematic does not show capacitor number 2 or resistor number 2 and installed components reflects same. Can someone be of some help here as to why? Was there a modification made not reflected on schematic? Or; is the long wire model different in the sense it does not require these two components? Thank you

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Dear Charles, I do not see in the diagram any numbering of capacitors or resistors. Can you explain e.g. the position or the values in ohms and capacity of the two components. Regards

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I have attached 2 schematics showing the capacitors and resistors. 1 with long wire antenna.

Attachments:

• s-7428-2 Firestone Firechief schematic showing capacitor and resistors (1275 KB)
• s-7428-2 Firestone Firechief radio schematic showing long wire antenna (291 KB)

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Dear Charles

The R2 resistor must be there, it is just not shown in the small part-diagram. It is part of the AVC. Without the resistor the AVC would not work.

The C2 is a very low capacitor, 25pf only. It will compensate the little different inductive of the of the input RF-transformer compared to the loop antenna, what also works as a RF-transformer.

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Thank you for your input.

I did notice the C2 was evident on the schematic with loop antenna and not shown on the long wire antenna schematic, however I am searching for the R2 not shown on either schematic.

 

Today I will go over both with fine comb again to determine where it my be represented.

 

I have already replaced the capacitors and resistors on the chassis with the exception of the C2 and R2 which do not exist on the chassis or schematic.

 

Hmmm

 

Thank you once again for your input.

 

Charles

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Dear Charles, R2 must be somewhere. If it is missing the AVC is not in function. If it is bridged, you’ll have no reception. Many times, these small resistors are hidden in an isolating sleeve.

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Interesting enough this radio is of earlier version and is the long wire antenna version of s-7428-2. 

Finished chassis restoration and it plays beautifully. I noticed by overlaying the back half of this radio schematic "portion reflecting antenna" with the long wire back half "reflecting long wire" there is not c2 or r2 present.

If this radio was produced by Emerson for Firestone then the schematic shown was never updated reflecting these changes.

In restoring I had came across several "original" dog bone resistors completely different than the schematic.

However with that said after restoration of chassis the radio plays fabulous.

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