Wow! Sotabeams Digital Audio filter

It all started with a 49er kit bought from China (ebay)
Its power output was 550mW. So, I made a few modifications and the power output raised to 2 W.

That was great but RX is a mix of signals.

It needed an improvement but build an effective filter will take a lot of time and effort.

DSCN4817

Just after finish the 49er I bought a Foxx-3 (20m) from Kanga UK.

Rx is better but as AF filter will be a added value…

Just about that time, Sotabeams announced a new pcb populated with SMD components without disclose the use.
Shortly after, Sotabeams stated that PCB is, in fact, a digital AF Filter.

Just about that time, Sotabeams announced a new pcb populated with SMD components without disclose the use.

Shortly after, Sotabeams stated that PCB is, in fact, a digital AF Filter.

FilterPCB__12720.1458836210.1280.1280.JPG
Was the this the answer that my TRX kits I needed ?
So, I bought one.

When it arrives I assembled it but until yesterday I hadn’t the time to fully test it.

Fully testing it means to me be on the air with it.

So, yesterday evening I went to 40 m band and no sound on my headphones…
What a hell is happening ?…

Cautious, I check the connections and, after sometime checking and rechecking, I found the guilty piece: A 3.5 mm female audio jack !
I picked another one from the junk box and “hellas” I have dits and dahs on my headphones. 🙂

Testing mean try which I did.

DSCN5203.JPG
I choosed the Elecraft KX-1. Filter set to 1 Khz (+/-).

First tried to change bandwdith with the switch.
Wow!  I even called Mrs DBS to notice the difference!

I had 3 stations in my headphones but when I narrowed the filter 2 are missing.
And now the small frequency steps aren’t useless…

From Sotabeams site : “The 1,000 Hz bandwidth filter is great for tuning around while the 300 Hz filter allows the user to “home in” on a signal of interest.” – Checked! And wow!!!! 🙂 🙂 🙂

I noticed that I could use the signal led (green on my set)to decode visually once the cw signal was tuned.

The overload led is also very effective. With it is very easy to set the AF input level.

The I tried the gain switch. Not a big deal but it was useful with some sort of signals. Another tool in this little device…

I measured the consumption. It was 31mA@12.5V DC with gain=1 and 35mA with gain=4.
Change of the bandwidth (W to N) just added 1 mA more.
So, considering the possible error in my multimeter, the consumption is within the range publicised by Sotabeams .

Now it goes to proper box.

For sure, it will be used in some SOTA activations, especially in those ones that occur simultaneously with CW contests!

Another good job from Richard G3CWI!

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