27-06-2017, 01:13 PM
(This post was last modified: 27-06-2017, 01:15 PM by Murphyv310.)
Hi.
Of course when I did the original conversion to my Wellbrook loop some years ago the main reason was the cost of Wellbrook's replacement amplifier that now stands at around £100.
Even with the two transistor balanced amplifier it performed as good if not slightly better than the Wellbrook did originally.
Eventually I had to make a more watertight solution and improve the circuits rejection of strong signals (I have an amateur 100 meters away) so as the loop would work or more importantly be reliable.
The two transistors need to be driven fairly hard and I eventually found the 2N2222A to be beefy enough for the job. Although I don't particularly like diodes back to back across the loop I decided in my case the advantages were greater than the disadvantages and that was the route taken, it has helped the intermodulation when the neighbour is transmitting, we now though work together in times on and off which suits us both fine.
TBH the first stage of mine & Gary's amp has been floating around the NET for many years, mine is a bitty different with different matching, values and transistors and seemed to be working better than the original circuit with gain up to 100mhz, and even this year it has given me some Band1 Spe reception form Russia and other countries on analogue, it's dying though.
Of course when I did the original conversion to my Wellbrook loop some years ago the main reason was the cost of Wellbrook's replacement amplifier that now stands at around £100.
Even with the two transistor balanced amplifier it performed as good if not slightly better than the Wellbrook did originally.
Eventually I had to make a more watertight solution and improve the circuits rejection of strong signals (I have an amateur 100 meters away) so as the loop would work or more importantly be reliable.
The two transistors need to be driven fairly hard and I eventually found the 2N2222A to be beefy enough for the job. Although I don't particularly like diodes back to back across the loop I decided in my case the advantages were greater than the disadvantages and that was the route taken, it has helped the intermodulation when the neighbour is transmitting, we now though work together in times on and off which suits us both fine.
TBH the first stage of mine & Gary's amp has been floating around the NET for many years, mine is a bitty different with different matching, values and transistors and seemed to be working better than the original circuit with gain up to 100mhz, and even this year it has given me some Band1 Spe reception form Russia and other countries on analogue, it's dying though.
