V1 is in the first RF module. It is a 6AB7 or a 1853 type.
When making pin-to-ground resistance measurements, make SURE the radio is configured like this. To locate tubes, see this.
There are two different wiring diagrams for V1. An early one shows pin 3 to ground, a later one shows pin 3 to the cathode on pin 5. It's assumed that with pin 3 going to ground, it's 'a very early' radio and with pin 3 connected to pin 5, it's 'a later early' radio or a late (SAX-28A) radio.
Resistance measurements made with Simpson 260.
"Open" or "no pin" means the tube does not use the pin but it might have been used as a junction for other components.
Pin to Radio Radio Radio
chassis #5 #6 #7
1 0 0 0
2 0 0 0
3 0 0 0
4 668,000 0.39 1,400,000
5 334 9,200 300
6 30,170 76,000 39,000
7 0.2 .2 .2
8 1,169 50,000 1,500
Resistance measurements made with Simpson 260.
"Open" or "no pin" means the tube does not use the pin but it might have been used as a junction for other components.
Pin to Radio chassis #_ 1 0 2 0 3 334 4 668,000 5 334 6 30,170 7 0.2 8 1,169
Pin to From the chassis docs 1 0 2 0 3 350 4 900,000 5 350 6 44,000 7 0.1 8 15,000
The old schematic shows variable caps on the secondary of the four transformers in the 1st RF module. The '5th' radio does not have them.
Tube pinout images are found on tdsl.duncanamps.com
For reference:
Page: /V1/V1_new.shtml
Last modified: Monday, 1 Jun 2026