Handy Reference Chart:
OEM batteries by series
71XX – Dark blue (C-S2) – 1000mAh
81XX – Gold/yellow (C-M2) – 1400mAh
83XX – Dark blue (C-S2) – 1000mAh
87XX – Dark Blue (C-S2) – 1000mAh
88XX – Green (lime) (C-X2) – 900mAh
Silynx Communications CA0006-00 Intercom High-Impedance Cable Adapter
$99.95
Raychem Capacitance - Impedance Calculator 1963 Coxial Cable Conductor Calif
$22.00
Vintage High Impedance Transducer/ Speaker Test Good
$25.00
CU350/PT TA312/PT Field Phone Impedance Matching Network 5915003925981 Military
$39.98
PIEZO HEADPHONE FOR CRYSTAL AND REGEN RECEIVERS (HIGH IMPEDANCE)
$15.98
Vintage Rare Western Electric 14B Rheostat 1B Impedance Bridge - USA
$349.99
Crystal Radio Higher Impedance Earphone Wide Frequency with Integral Jack
$18.00
Shure Reactance Slide Rule & Amphenol RF Cable Selector Constant Impedance 1947
$11.99
Home grown Antenna Impedance Meter from ham radio estate
$97.50
Impedance Matching Trans Formers Axetrak
$69.17