Ubitx HF

My uBitx story

This started June 2018 when a work college showed me a radio kit he had ordered. 

 It was the Ubitx and it blew me away what it could do for such a low price.  That night on the net I read of other ‘s building it with lots of mods and a touch colour screen.  My god this is amazing.  The next night I ordered one from HF signals site.

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Funny thing is I still had a Bitx20 to finish building,  this project has been on going for 3 year.

Wait seemed to take for ever but it gave me time to think, what this radio going to look like.  Back in 1994 I wanted to make a fox hunting receive for HF to 6M.    

The ZBR fox hunting radio only got to the halfway point when I gave up.  This gave me the idea of the format I wanted for the uBitx.  The radio would slide into a amo box for portable work.  

My design thinking has been influenced by my other new hobby, 3D printing.  This has opened up a whole new world of what I can do.

Also I had a dream of upgrading my uBit with a touch screen and KD8CEC firmware.

He has done a fantastic job and its great he shares his stuff to us all.

So I did this first drawing of what I want the uBitx to look like, drew it while I was a little bored.  Then the idea grew.

As this is a transceiver it has a RF power amplifier, heat is the issues that needs to be sealed with. No fans as they need power and are noisy. I want the plugs and sockets on the front or side.   I don’t like the idea of stuff coming out the back as this radio will portable and live in a carry shoulder bag.

I knew the firmware allowed the radio to go down to 160m and 473kHz but at the time I had no idea it worked so well down there.

I like to start back wards  I make the chassis and case first and work out the insides later.  I think I like the creative bits first then the electronics last. I rather know what space I have to work with first. As you can see I like to hand draw what I think it should look like then I will do the drawing on the CAD later. I then do the hand s on the metal work. Being a service technician by trade I will it the be serviceable.

Early testing issues

In early testing I found the transmitter and some unwanted products when transmitting. especially when over driving the audio. There was plenty of talk in the forums and bagging of the design. Hay its cheap what do you expect!

I found most of the problem reduced quite a bit when I built the chassis and mounted the RF PA gets on the heat sink. The rest of the issue can be fixed by replacing the low pass filter relays with proper RF relays. I haven’t done this because it cost nearly as much and the uBitx cost me. My radio is with in the FCC rules if not over driven, im getting -34dBm on the third harmonic at 15watts PEP. This radio has no ALC so that can easily be done at a later date. I don’t have the issue normally.

FCC rules is tighter than ACMA rules.

The two tone test is acceptable to me.

The next problem was the audio amplifier, it does not have the current drive the speaker I choose. I use a mini speaker that has a good bass and treble response, so it need a bit of grunt to drive. Im going to sole this with another amplifier that incorporated an audio mute.

This project has be put aside while I play with more exciting stuff.

I have filters for the 630 and 160M band to install, swell as a DSP and audio amplifier.

A Codan style mute circuit, only opens up when it detects voice.

This all requires a PCB to be designed then made, I have allowed for many extras in the chassis.

The Ubitx lives next to my bed side and used most nights to listen to ham radio or aircraft. So it’s being used a lot, hence why I probably haven’t finished it yet.