SB220 SB200 SB-221 SB201 Relay 120Vdc

SB-200 SB221 SB201 SB-220 Antenna Relay

Installation Instructions Heathkit 69-55 or Heathkit 69-5 improved relay system 


The patent pending RL3pDT120dc is a superior replacement for the Heathkit K1 69-55 relay, Heathkit 69-5 relay, and similar 110 or 120Vdc linear amplifier relays including Collins and other brands.

There is no longer any need to use hard-to-find slow obsolete relays in SB200, SB220, SB230, Collins, and other amplifiers using high voltage dc antenna transfer relays.


Heathkit 69-5 69-55 Relay

Universal 120Vdc relay contact timing tests

This board is a direct drop-in superior replacement for all 120Vdc antenna relays used in SB220, SB200, Collins 30L-1, and other 120Vdc antenna relays.

This board is time-sequenced to always close antenna contacts slightly before and hold the antenna contact closed slightly after the control signal and input/bias relay release.

Yellow color = relay keying line (20V per division)

Aqua color = RF Output Close time: 4mS

Red color = RF Input and bias contacts: 7mS

Green color = unwanted back-pulse

Isolated bias contact closes with input RF relay.

Heathkit K1 69-55 relay Heathkit 69-5 relay

Wiring connections Heathkit 69-5 69-55 120Vdc relay (patent pending)





SB200 relay

SB200 Antenna Relay


Sequenced 120Vdc relay system board only $59.00 shipped USA
Sequenced 120Vdc relay system board with all necessary hardware and cables  $69.00 shipped USA

Parts ORDERS or parts questions go to