Thursday, 9 February 2017

RX antenna isolator

I homebrewed and tested the G3BJ RX antenna isolator  last weekend. Implemented as M0VKY

G3BJ RX antenna isolator 

The half size K9AY RX antenna is close to my TX doublet [about 5m]. There does not seem to be much power coupled into the RX antenna when I transmit with 100W on 40m. I measured the DC rectified voltage on a dummy load connected to the RX line at approx 300mV.

Testing RX antenna isolator with 817 and a dummy load connected to TX.

The Aluminium boxes by Bitbox are inexpensive and easy to work with. I might box in them some of my other kits [BBGen,...]

Many thanks to Don G3BJ and Simon M0VKY for sharing this.

73 Angel

Wednesday, 8 February 2017


The ionosphere was kind yesterday and delivered 2 new DXCCs on 20m band.

I got home before sunset and the Italian expedition to Central African Republic was booming here.
After 15min of calling, I managed to the get through with my 100W and doublet around 5 UP.

A bit later I also heard - on the noise -Patrice TY2BP in Benin and as the signal raised a bit, I was able to make the QSO.

I noticed over the last couple of dates that switching off the AGC gives a better SNR - cleaner and easier to copy weak signals. I wound down the RF gain a bit and keep the vol to min or close to min - the Yamaha CM500 I use produce plenty of volume.
I am not sure about the NR2, the audio seems too warble.
My QTH here in the city is very noisy.

73 Angel