Antenna Analyser

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.

DG7EAO

K6BEZ

VK3YY

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

ARDF Fox Hunting

Receiver for 2

I need one more receiver for 2 meter so i order one more from 2m G3ZOI Receiver ROX-2X rox-2x. I have heard that antenna in col-fiber should work so I wont to try if it is possible to make one.

1 See if it is possible to se impedance response.

2 Compare sensitivity with the old measuring tape antenna.

I search for inspiring and stay for this one. dk7zb 3el yagi

Here is response, little bit shorter balun has been fine (next time!).

The Result

Next is time for testing on a real competition.

80M Foxes

We need 2 more foxes for 80m so this was finalized for or competition, in the spring. A few batteries has passed, so I must check the charger, and by more for spare parts.

80M Receivers

I has struggle a lot with the latest 80m foxes (see Februari 2015), but the constructor Bo SM5CJW has help me and now they both are working, really good side tuning really clear. Hope also to check them in a competition later on.

Stay tuned I work on 2 more project 1296 Transverter and Antenna analyzer.

73 de Leif SM4HNG.

Transverter 1296 MHz

I came across the W1GHz side w1ghz, and this time i toke contact with Paul and order some boards. There is a lot of information on this sides. I have no started to build the LO 1152 MHz.  Here is some measurement from this.

Her is VCXO:

I start with a more simple VCXO not phase locked I can run practice on the beacon close to me 25 km or so to se ho accurate it will be, if not order more parts and get it locked to GPS.

Here is LO:

The 288 MHz Filter

The 1155 MHz filter

The Lo measured @ Mixer, 20 dB atten befor RF-Explorer.

The Transverter 1296 MHz, is now tested and it seems working ok. I am not sure about output power perhaps 5-10 mW, so I start working on drive stage.  Plan is to have 2,5 W out, Reddy for new PA!

It works so grate, her is a short video.

Project Minima has come to the end.

The distance to IW2KGW is 1569 km, report 44, antenna 3 el Beam.

The distance to SP6PYP is 789 km, report 57, antenna sky-loop 82m.

Modification not menschen earlier.

CW modulation take the signal from collector T17 and R43 connect 2,2uF and serial 180kohm to mic in.

This was adjusted after R33 220ohm changed to trim pot 500 ohm, to adjust modulation from mic.

100nF put in LP-Filter close to T+ pin (input regulator).

100nF put in LP-Filter close to +12V pin (input regulator).

I have no run QSO on 80m, 40m and 20m. I rely like the little fantastic Rig. It has built in CW memory for short CQ. Also QRSS Message not practiced yet. I think I have not found all feature yet.

It is close to unrealistic what is possible with this small rig. Width 18cm Depth 20cm Height 8cm Weight 1150 gram.

No I stopped soldering, no more measurement and go for practice with this QRP MINIMA.

If its unclear wat I have done you are welcome to email (Calsign@gmail.com) if you won’t more detail. Or put in a comment down hear.

SW is very close to Eldon Brown work really nice,  Eldons Code TANKS a Lot.

I add a Rx-preamp  +14dB its perfect when its weak signals.

Hope to her you on the band.

73 de SM4HNG Leif

Hard to get all parts in minima to working together.

I have used the receiver in the summer to listen on 80m band, when I was in the shack. Now when all puts together it starts sound very strange, I found out that the capacitor 330uF clos to LM386 Vcc was not connected! It solves this problem.

Strange behavior when modulation, needs more decoupling at mic amplifier T13 R34 10 ohm changed to 47 ohm, C43 50uF changed to 470 uF.

To get little more drive I change PA-Drive 2N3904 emitter resistor from 22 to 10 ohm, see Pa driver.

In transmit the modulation passes to LF amplifier, a FET 2N7000 shorts T15:B to ground, gate to 47kohm to +T.

Found that output is rather high even if no modulation. Put in a classic 10 turns trim pot 100 ohm to D3,D4 give around -40 dBc with no modulation.

Last problem on 21, 24 and 28 MHz is lot power when touch ptt., found out that shielding was needed between LP-Filter after PA and LP filter on main board(60 dB gain).

I will try to put up a vide as proof of working transceiver, its not a hi-tec. TRX but its working and I have learn a lot. Have made around 10 QSO, One Sweden to Netherland 59 report on 40m.

Stay tuned one last nots from this project.