Cheap High Power 50 – 144 MHz Relay with “N” connectors

Cheap QRO Relay 50 – 144 MHz with high isolation and “N” connectors

Intended to switch antenna to QRO or preamplifier without need for another isolation relay. This N Connectors High Power Relay is good enough to protect any sensitive preamplifier. Relay is good for HF, VHF contests and for EME.

How to make N Connectors High Power Relay:

To make this QRO relay you need: 200 W soldering iron to solder “N” connectors. 60 – 100 W soldering iron to help soldering big surfaces. 30 W soldering iron. Basis is 1mm copper 100 x 36 mm. Distance between connectors 34 mm.

Cheap High Power Relay 144 MHz 50 MHz 2 meter 6 meter N coonectors

 “NC (Normally Connected)” is TX side”NO (Normally Open)” is RX side. Relay is energized at receiving. It allows to have same power for preamplifier and relay. Bill of materials:2 pcs. of 0.5mm copper. Approximate dimensions: 

Cooper part

 These copper sheet are used to shorten central pins and NC pins of relays. Inside view: 

Cheap High power 144 MHz 50 MHz Inside view

About 35mm UT-141 Teflon cable (RG-402, RG-316). Find it here: RG-402 Coaxial Cable

About 35mm UT-325, EZ-325 or other solid Teflon 8mm cable. Or RG-401 (UT-325 will be better). Find it here: RG-401 Coaxial Cable

2 pieces of Finder 41.61 12V relay: Finder 16 A 12 V Relay or Schrack RT314012: Schrack 16 A 12 V Relay

1 piece Isolation relay Omron G6Z-1PE-A from here or from here.

High power Relay 144 MHz 50MHz Inside look

How does it work?

On transmit side signal passes through 2 pcs 16A relays in parallel to “N” connector
On receive side signal passes through isolation relay Omron G6Z-1PEA to Teflon “N” connector.

Relay Schematics
Relay Schematics 2

Improvements relative to “Cheap High Power 50 / 144 MHz Relay 7/16 DIN connectors schematics”

Lower losses (thanks to shorter cables) and better isolation. Thanks to inductors and capacitors between relays. Everything is on above schematics.

How are characteristics measured?

1. HP8753ES Network Analyzer was calibrated Full 2 port.

2. Through calibration was done with N – N barrel.

3. All losses are “barrel losses” + presented data  TX side. Relays not energized.


S21 (Insertion loss) HF – Insignificant, 50 MHz – 0.0099 dB, 144 MHz – 0.035 dB

S11 (Return loss) HF better than 45 dB, 50 MHz -40 dB, 144 MHz -29.5 dB

S11 and S21 TX Side Relays Not Energized

TX side. Relays energized. S21 measurements: 50 MHz   -23 dB and 144 MHz  -14.8 dB
S11 S21 TX Side Relays Energized

“N” – “N” RX side. Relay not energized. S21 (Isolation) HF – Better than 100 dB, 50 MHz – 96 dB, 144 MHz – 83 dBS11 S21 RX Side Relay Not Energized

“N” – “N” RX side. Relay energized.

S21 (Insertion loss) 50 MHz – 0.03 dB, 144 MHz – 0.069 dB

S11 (Return loss) HF better than 37 dB, 50 MHz -32.7 dB, 144 MHz -24 dB

S11 S21 RX Side Relay Energized

Relay may be placed in a waterproof plastic case for outdoor use. You can look at our “DS” Plastic box for outdoor use.

This cheap 50 / 144 MHz relay as seen has very good characteristics adjusted for amateur use on EME, HF and VHF contests. There are no need for another isolation relay. You can connect preamplifier directly.

Like this one: PGA-103+ Wideband Low Noise Amplifier

Or with Band-pass filter:144 Mhz Band-pass Filter.

32 Ampere contacts are way beyond commercial coaxial relays, and will provide good margin for today’s high power demand.

High Power 50 / 144 MHz Relay


If You are unsure how to make relay do not hesitate to contact me. If You do not have enough time to make relay, you can contact company “Dual” to make one for you. It is possible to make any combination of “N” male – female connectors of your choice. Just ask.

This presentation is for amateur use only.

73 Goran YU1CF