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uBitX module - Mods 2

With just six mods my uBitx is far from ready. So on to the next page full of mods.

7th mod : Connect the world.

Doing software for a daytime job means that I often change or refactor code and for my custom firmware it isn't any different. So it would be nice to be able to update the firmware on the raduino without having to open the case everytime. For a other project I use a panel mount USB cable and I thought it would be a great adition to my uBitx.

For this mod I used a panel mount USB Mini B male to USB B cable (google : "Panel Mount  USB Mini B Male to USB B "). Now I can update the firmware without having to remove the enclosure covers and even use the CAT option.

8th mod : RX/TX main dail

My FT897 and FT817 have a RX/TX led indicating in green that the rig is in RX mode, and indicating in red that the rig is in TX mode. It's the fact that the front panel from my uBitx is getting a little full with all the buttons, knobs, chassis parts and the rather large speaker (starting to think i would have been better to install it in the top enclosure cover).  But it's a thing I have to live with although I could decide to create a new cover from scratch (which maybe never happen).

Ok, back on topic. In the uBitx there is a RX and a TX 12V switch line created with the RX/TX relay controlled by the T/R signal from the raduino. Those lines could be used to light up a BI color Red/Green led with a common cathode.

The connection on the bottom of the PCB are shown below (the relay is located near the finals).

When these spots are located, you just have to solder 3 wires to them and add a 470 ohm resistor to the RX and TX wire. For the connection I used a 3 pins Dupont connector which fits perfect on the bicolor led.

Because I have made the maindial from polycarbonate, I drilled a hole just below the rotary encoder and put the bicolor led in it. The clear texture of the polycarbonate lets the light go through showing the RX/TX state.

Then its time for the smoke test. Rig powers up in RX and is showing . . . . yellow. Ok, so never trust a bicolor led out of the junk box when you just tested the red part. But ok, it's not red, so RX (confirmed by no TX in the display).

Squeezing the mike and the uBitx switches to TX and showing the red light below the mai dail. Mod confirmed.

Todo : buy a new 5mm bicolor red/green led with a common cathode. :-)

Item from todo list [check]. Bought a red/green bicolor led and the green glow looks nice. Happy OM :-)

 

9th mod : AGC.

Like allready said in the first mod, Donald ND6T has a nice RFGain (basically a RF Attenuator) for the uBitX : http://www.nd6t.com/uBITX/RF%20Gain.htm which also can be used as a good startpoint for adding a AGC http://www.nd6t.com/uBITX/AGC.htm.

I tried to build the AGC as small as possible, but due to functional issues (pain in my hands) I couldn't make it as small as Donald has made it. But overall I'm happy with the result. In adtion to Donalds design I added a small header to it so I can select 3 different release times (resistor 330K, 680K and 1M). By default I have put the jumper on the 1M positions.

It's a tight fit due to the USB cable but it fits.

After installation I hooked up my scope to the junction C4, R5 & R6 and when I tuned the band, I could see that the AGC in reacting fast to the noise pieks. What I did find out is that the RF Gain / AGC combination has some dB attenuation on the speaker output. But that was to be expected.

I have connected the spare A7 on the raduino to that junction for future implementing of a  S meter in the custom firmware. But first I have to make a stable and output adjustable noise generator to measure the reference signals. Check out this wikipedia page for the levels.

Continue to my uBitx video page....


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