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Paul,

The sbitx is not a simple rig, it is minimally designed. It has an in-channel dynamic range of 80 db. That means, it needs more than 16 bits of adc resolution. The wm8731 has 24 bit resolution at 96000 samples per second. The effect is dramatic.?

You only have to listen to the rig to know the difference.

It looks simple as the circuit is smaller than even the bitx40. But a closer look reveals changes. The front has no early amplification at all and the passive KISS mixer directly feeds a crystal filter at 40 MHz. At 40 MHz, there is 6 pole filter that has 70 db rejection of the opposite sideband, the IF amplifier has +30 dbm intercept. The audio amplifier (it should actually be called the second IF as the signal is centered around 24 KHz) was especially designed for rigs like this by W7ZOI to exhibit strong in-channel dynamic range.

The radio is a balance of minimalism vs function.

- f

On Sat, Jul 2, 2022, 11:26 PM AA9GG <paul.aa9gg@...> wrote:

Curious why you went with the wm8731 codec? I've never used one. What is its claim to fame? That thing looks pretty crazy to me for use in a simple rig.

On Sat, Jul 2, 2022 at 9:25 AM Don--AE4DW <AE4DW.Don@...> wrote:

On Fri, Jul 1, 2022 at 08:19 PM, Ashhar Farhan wrote:

Scott,

We will still be giving out the basic kit at a much lower price (about the same as the ubitx).

The main board is almost twice the size of ubitx. We had to use much more costlier transmit filter components, large heatsinks to larger T50-6 toroids and 250v, RF grade capacitors. This is a 40 watt radio.

We are more than happy if we can cover costs. Unfortunately the timing got us on the wrong side.

But here is the upside. There is nothing in the design that is unobtainable even in these days of shortage. The circuit is all discrete and easily put together from your junk boxes. Substitutions are easy too. The only critical thing is that you must use a raspberry pi and a wm8731 codec (still available as a board from mikro for 20 dollars). You can still scratch build it yourself, at least a QRP version for less than $100 dollars (if you already have a raspberry pi). It works equally well with a regular hdmi display.?

It is a bit of an effort, but someone can take a stab at porting the code to a PC too.?

?

So the basic kit availability is further down the line? Only the full kit available initially?

--

Paul Mateer, AA9GG
Elan Engineering Corp.

Ashok,

Check is all three Raduino clock signals are working. I suspect not.

You will need some instrument that can count or scope 100 MHz.

Good Luck,

Raj vu2zap

On 04/07/2022 4:38 PM, VU3KFK wrote:
> Hi all,
>
> I think finally I have found that my uBitx is unable to receive in 7
> MHZ band. And other bands also poor reception. After few days checking
> for 40m band reception, i was unable to receive anything, even in the
> HF nets that conduct in my area, I cannot hear anyone. My antenna is
> EFHW and SWR is below 1.5.
>
> To check the problem, this is what I did.
>
> I have a crystal oscillator for testing crystals. I took that
> oscillator and installed a 7.023MHz crystal on it and turned it on.
> O/P connected to frequency counter to be sure the oscillator is
> running. Attached a 1 m long wire to uBitx antenna port and placed the
> end of that wire very close to the crystal oscillator. In this
> situation I am supposed to receive 7.023 as a CW signal and also in
> LSB i should be able to hear it if all is OK. uBitx keep on generating
> white noise as it always, not even slight change in noise pitch. Looks
> like uBitx cannot hear anything. Where should I begin troubleshooting ?

Looking amazing, Ashhar!! Now for MY question: which versions of Raspberry Pi will work with the Sbitx? I've bought a couple of them, intending to use them in other as yet unstarted projects, easily outclassed by the Sbitx. Hopefully one can be used!! -- Rich WB2GXM

------ Original message------

From: Ashhar Farhan

Date: Fri, Jul 1, 2022 8:19 PM

To: [email protected];

Cc:

Subject:Re: [BITX20] Sbitx manual

Scott,

We will still be giving out the basic kit at a much lower price (about the same as the ubitx).

The main board is almost twice the size of ubitx. We had to use much more costlier transmit filter components, large heatsinks to larger T50-6 toroids and 250v, RF grade capacitors. This is a 40 watt radio.

We are more than happy if we can cover costs. Unfortunately the timing got us on the wrong side.

But here is the upside. There is nothing in the design that is unobtainable even in these days of shortage. The circuit is all discrete and easily put together from your junk boxes. Substitutions are easy too. The only critical thing is that you must use a raspberry pi and a wm8731 codec (still available as a board from mikro for 20 dollars). You can still scratch build it yourself, at least a QRP version for less than $100 dollars (if you already have a raspberry pi). It works equally well with a regular hdmi display.?

It is a bit of an effort, but someone can take a stab at porting the code to a PC too.?

- f

- f

On Sat, Jul 2, 2022, 1:03 AM Scott KE8KYP <scott_massey@...> wrote:

Hi Ashhar,

I too have been anxiously waiting for the sBitx.? I am a bit disappointed that the cost has creeped up but I do understand the problems.? You have to make money.

I assume that the $500 kit is for everything which I may end up buying but I was seriously considering a customized case and maybe a larger screen.? When I bought the uBitx V6, I bought the Full kit but I almost ordered the Basic kit.? Is that the marketing idea you are considering?? Are there other packages without a display and/or Pi as options?

Looking for to it.

Thanks, Scott?

Hi Ashhar,

I too have been anxiously waiting for the sBitx.? I am a bit disappointed that the cost has creeped up but I do understand the problems.? You have to make money.

I assume that the $500 kit is for everything which I may end up buying but I was seriously considering a customized case and maybe a larger screen.? When I bought the uBitx V6, I bought the Full kit but I almost ordered the Basic kit.? Is that the marketing idea you are considering?? Are there other packages without a display and/or Pi as options?

Looking for to it.

Thanks, Scott?