I start locking
in eBay for bye a Antenna Analyser when
i found a lot of interesting design, and i realised hat it is not so many parts
needed to build one.
Here is a
few links i start lock att.
I tried the Arduino code from DG7EAO and the exe it
works (no HW just the display), and start to modify the code. I won’t a more
standalone without computer control.
I ordered a
2,8” TFT Display.
Power detektor board AD8307.
FTDI Basic,
encoder and a box.
I has a DDS
board DDS60 from midnightdesignsolutions. DDS60
I has a Arduino mini pro board.
I read a
lot of information on SWR detectors, first the ide was to have Pforward and Prevers at
the same time, but all result and try was not god enough. So i realise that an
RL-Bridge was much better, the bottleneck
that it attenuate the signal from the DDS 12 dB, docent mater for an
analyser. Normally the bridge has a
transformer on output, but i realised hat i can change the power detector to have
differential input. Disconnect pin 2 RF-
100nF from ground and connect to input, also change R at input from 100 ohm to
50 ohm, i don’t know how necessary it is! To avoid trafo is good for low
frequencies .
The Power
meter AD8307 has a dynamic of 80-90 dB. I measured the response from my
generator -65dBm and +5 dBm, it give me 25,2 mV/dB. To use in SW.
The DDS60
has +8dBm out so i decide to attenuate
3dB if its not 50 ohm out ?
External
Aref 2,7V matching AD8307 dc out around 2.5V max.
The only
thing i have o do was the RL-Bridge and a 3.3V regulator, all other is parts bye.
So long i am satisfied with the result RL @ 50 ohm
termination is as highest value 27dB @ 1 MHz it is 60 dB.
It is more to do with the SW, but i has came
to memory limits, but it can be solved, i hope.
Here is the schematics.
After the break i should fix the software and go to a friend
with a lot off antennas and do a accepting test.
No i work with the 1296 Transverter, stay
tuned.
73 de SM4HNG
