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.
“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:
These copper sheet are used to shorten central pins and NC pins of relays. 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
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”
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
TX side. Relays energized. S21 measurements: 50 MHz -23 dB and 144 MHz -14.8 dB
“N” – “N” RX side. Relay not energized. S21 (Isolation) HF – Better than 100 dB, 50 MHz – 96 dB, 144 MHz – 83 dB
“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
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.
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