A few years go I also made a LNA using a MGF1302 FET , and it always worked flawlessly. Although it sometime gave up and was distroyed again because I forgot to take it out of the transmission line when going to transmit, then I had to renew the fet again,..
A lot of times you read a LNA will make your
station receive better,..it doesn`t, what a antenna doesn`t receive
can`t go to the receiver so it also can`b be amplfified by a LNA. It`s a
usefull tool to overcome the losses in your transmission/receive line.
Those signal would be lost in the line and now it is amplified so it
will come through towards the other end at your receiver.
I ordered the parts at
, capacitors used are ATC-100B SMD. Trimmer cap a Johanson 5476 Hi-Q
one. These parts are more expensive as regular ones, but hopefully I the
LNA will be better as the last one.
build the LNA and adjusted it on frequency/maximum gain. So let`s see
what is the difference between the old one and this one connected it
between my antenna and my TS790 listening the dutch beacon on
144.416Mhz. I can say, a big improvement, if I connect the old one
(MGF1302) the noise level increases with about 4 S-point toghether with
signal. When I connect the ATF54143 LNA only the signal increases, the
noise level increases only one S-point. So the signal/noise ratio is
much better with this Low Noise Amplifier. This is just what I needed
for weak signal communication using WSJT.
Beside the LNA there are coming a few things extra.
This will be two integrated RF relays. Wired so I can switch the LNA on
or off again in by-pass modus. Switched by hand on the PA by a switch or
switched off in by-pass by the sequencer in the PA when it going to TX.
This board with the extra relays will also be made for the 432Mhz LNA.
The changed circuit board with the relays is seen at
the right. With two extra PIN diodes to secure the ATF54143 for
static. And the two relays to switch the LNA in by-pass. The board used
is 0,75mm thick PTFE board. Bought at a HAM-fest.
The board has been changed again. Version 3.0 has an extra filtered
output. This filter will be three pass helical filter. These are made by
TOKO. Adjustable from 140-180Mhz with a bandwide of approx 8Mhz. While
the LNA has enough gain, the losses of about 4˝dB
through the filter will be compensated enough by the LNA. The board also
has a little change, more 50Ω stripline and mitered bends towards the
ATF54143. The two PIN diodes are now changed to just one at the input in
front of the input relay.
The helical filters are:
For 2 meter band it is the TOKO FE-7H3-160.
For 70cm band it is the TOKO 5CHT-493S-1072A.
For 23cm band it is the TOKO 5HW-125055F-1305.
For the 23cm LNA (1296Mhz) a new board will be designed. Also with
switching relais and helical filter on the output. Also with the
ATF54143 EPHEMT FET.
For the board I used the design of OK1DFC. I made a few changes to it to incorporate the relays and helical filters and the by-pass stripline. Also looking at the Agilent datasheet for it.
V1.0 orginele uitvoering nagebouwde print. 2009
V2.0 Print met opgesoldeerde relais. 2013
V3.0 Print met relais en bandpass filter. 2013
renewed on 10the August 2014