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37-650 Tuning Capacitors
#1

Icon_confused: On the side of the three gang tuning capacitor on the above set two of the gangs have single terminals at the bottom and top between which is a straight wire. The leads from the band selection switch to the grids of the RF Amp and Det/Osc tubes connect to the bottom terminals respectively and the top terminals connect to the grid caps of the tubes. Is the wire special resistive wire or was this done for ease of assembly? Why weren't the leads from the band switch run directly to the grids instead of the bottom terminals and then off the top terminals. I forgot to add that there is no connection from the terminals to the condensors, they appear to be just connection points. Anybody can explain this I'd appreciate it. PL
#2

Is the wire connected at both ends? If not-

In some cases a neutalizing/feedback wire is used on top of tuning caps to kill unwanted oscillation especially at the high freqs; the wire is actually a capacitor and changing it's position will often help. Usually it runs from the stator of one tuning cap to somewhere near the stator of the adjoining cap. When I have particularly nasty high-end problem with a radio, this is a solution that I sometimes use.

I don't know if this is what you are describing, but I thought I would suggest a purpose for your extra wire- maybe a tech put it there years ago.

Pete AI2V
#3

Pete, thanks for the reply. I examined this further and as far as I can determine the wires are not resistive. The single terminal board on the bottom and top of the condensor are isolated from it. It seems that this was done for production line purposes. The leads from the band switch come out of the chassis and immediately are connected to the bottom terminal, then the grid cap wires are attached to the top terminals. I'm guessing that shielded wire would have been to expensive and by having that wire between the terminals (it's straight as an arrow and taut) placed there by the manufacturer of the tuning cap provided the shortest distance between the two points. If anyone else has any ideas please join in. Pat




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