Re: smdBITX DDS VFO Introduction

Yannick DEVOS <yannick.devos@...>

Hi Farhan, Elia,

I confirm Si570 as local oscillator for the VFO is really good.
Last saturday, propagation was poor but I was receiving ZS6CYY around 52 and W6CCP around 53 (he is normally a loud 57 at least).
I was using my Yaesu FT-100 and my 40m delta loop. The FT-100 is quite sensitive and is considered as a quiet receiver, the delta loop is also a quiet antenna.
I switch on my Bitx version 3 with Si570 VFO and the receiving was even better! I have no s-meter but the sound was clearer, with less noise.

By the way This also confirmed me that my bad modulation on TX is not coming from the crystal filter or the VFO.
Perhaps it is a problem on my power supply being undersized.
I will also try to add some ferrite on the power cables and AF cables...

Regarding the BPF, here is a site VU2POP gave me about SDR :
Among the kits there is this Band Pass Filter that could be interesting...

Thanks Farhan indeed for the great design you gave us, and thanks Raul, Dan, Arv, Doug, Elia and other for having contributed to make the Bitx a real international star on the QRP scene.

Yannick DEVOS - XV4TUJ (Blog in french) (web page in english)

Le 25 mai 2010 à 13:48, Ashhar Farhan a écrit :

why not use the Si570 instead of a DDS?
- farhan

On Tue, May 25, 2010 at 6:28 AM, 2E0ZHN <eliamady@...> wrote:

Hi All,

With the kits now on their way I turn my attention to the DDS VFO and BPF Filters. This is still in the early stages of development but here are the features I aim to have:

- Coverage for 160m to 6m bands
- User defined IF
- Switching of BPF and LPF
- USB, LSB and CW mode switching
- S-Meter
- SWR and Power Meter
- VFO A and VFO B

Once I achieve the above I may try to add the following:
- VFO function turning this into a signal generator
- Sweeper function with a Ramp output

Will keep you posted of my progress.

73's Elia, 2E0ZHN


Yahoo! Groups Links

Join to automatically receive all group messages.