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 relay is good enough to protect any sensitive preamplifier.Relay is good for HF, VHF contests and for EME. To make this QRO relay you need:200W soldering iron to solder “N” connectors.60 – 100W soldering iron to help soldering big surfaces.30W soldering iron. Basis is 1mm copper 100 x 36 mm.Distance between connectors 34 mm. 


 “NC” is TX side”NO” is RX sideRelay 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: 


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


About 25 mm UT-141 Teflon cable (RG-402, RG-316)

About 20 mm UT-325, EZ-325 or other solid Teflon 8mm cable.
Or RG-401 (UT-325 will be better)

2 pcs of Finder 41.61 12V relay

or Schrack RT314012

Isolation relay. Omron G6Z-1PE-A


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.


 Improvements relative to “Cheap High Power 50 / 144 MHz Relay 7/16 DIN connectors schematics” 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 dB144 MHz – 0.035 dB S11 (Return loss)HF better than 45 dB50 MHz -40 dB144 MHz -29.5 dB


TX side. Relays energized.S21
50 MHz   -23 dB
144 MHz  -14.8 dB
High-Power-Relay-S11-S21-TX-Side-Relays-Energized“N” – “N” RX side. Relay not  energized.S21 (Isolation)HF – Better than 100 dB50 MHz – 96 dB144 MHz – 83 dB


“N” – “N” RX side. Relay energized.

S21 (Insertion loss)
50 MHz – 0.03 dB
144 MHz – 0.069 dBS11 (Return loss)HF better than 37 dB50 MHz -32.7 dB144 MHz -24 dB


Relay may be placed in a waterproof plastic case for outdoor use.

This cheap 50 / 144 MHz relay as seen have 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: Or with Bandpass filter: 32 Ampere contacts are way beyond commercial coaxial relays, and will provide good margin for today’s high power demand.  


 Compared with relay with 7/16 DIN connectors: 


 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 about 95 EUR (indoor use) 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