21-70-25-xx-T Series

Image of 21-65-25-xx-T Series

21-70-25-xx-T Series

21-70-11-xx-T Series, 450-470 MHz T-Pass Expansion Channel assemblies consist of the following items:

  • A 10" 3-quarterwave T-Pass® cavity filter
  • A dual ferrite isolator, with RF loads and coaxial cable for connection to the cavity
  • An RF sampler to measure RF power reflected into the isolator output load
  • Isolator and channel mounting hardware


Expansion assemblies for channel 2 and higher are supplied with a thruline of the correct length for the new channel frequency.

Starter channels (channel 1, bottom) are supplied with a short circuit on the T-Pass loop.

Ordering Information
To order an expansion channel, specify the following:

  • Frequency and position of all channels in the system to be expanded
  • New channel frequencies
  • Transmitter output power on all new channels


T-Pass® Expansion Channel Guide
Tech-Aid No. 93002 (Lit. No. D3011F93) provides a listing of expansion channels by frequency range and isolator load power, as well as diagrams to facilitate selection of the correct channel configuration. Expansion channels are also available with 60-watt loads. Consult with factory.


  1. Contact factory on expansion channels for frequencies below 220 or above 250 MHz.
  2. "xx" in model number describes isolator and load configuration: 2B = 5W/25W; 2C 5W/60W; 2D = 5W/100W.





Product Specifications 
Item No21-70-25-xx-T Series
Item Name450-470 MHz, T-Pass Expansion Channels
Frequency Range450-470 MHz
Cavity Diameter10"
Isolator Power150 W
Isolator Load Pwr ContinuousSee Notes
For Use with Multicoupler - Model No73-67-25 Series
For Use with Starter Channel - Model No21-70-25-xx-TS

Compatible Devices:

Image of T-Pass 73-35A-01

73-67-25 Series
406-512 MHz, T-Pass Combiner, 10” Cavity