Peaberry help

General discussion and support for the Peaberry SDR V1.

Peaberry help

Postby Rdavenport » Wed May 01, 2013 10:57 pm

I traded for it for and the owner said it was for 40/30/20m. . I am disabled and unable to work with the small parts. Can I send it to somebody and you modify it to cover 40/20/17m? Can you also check it out? I am primarily interested in SSB.



Randy ka4nmathe
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Re: Peaberry help

Postby w8kfj » Thu May 02, 2013 2:57 pm

Hi Randy

I too built my Peaberry for 40-30-20, but was surprised to find it worked pretty well on 80, but the receiver was pretty punky on 20. And surprisingly 17 was about as good. Try things out! It may be that just by changing the LPF components to 17, it will work about as well as 20. Where are you? Maybe you can find somebody nearby. If you attend some local club meetings maybe you can find some knd soul.

I built a 15 Watt Amp - filter - preamp box that works pretty well on 80-40-20. Makes a nice little package.
Anybody else have a similay experience with band choices?

Dave
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Re: Peaberry help

Postby hansvi » Thu May 02, 2013 5:52 pm

It's funny you mention that, Dave, because I was looking into exactly the same issue. It's one of the reasons I looked at the tx power. I was already thinking I placed the wrong capacitors or did something wrong with the coils. I even triple checked that I had marked the correct configuration on the work sheet.
Anyway, tomorrow I will go to the local HAM club, and I hope I can find the time (and help) to do some tests there with a signal generator. Although I also have a class (I'm still studying to get my license).

I just tested mine on 17m, but I didn't hear a thing.

Greetings,
Hans.
73,
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Re: Peaberry help

Postby hansvi » Fri May 03, 2013 10:47 pm

Dave,

I've just returned from the radio club. With the help from some people, we determined that the main problem was an increased noise floor at 14MHz. In fact it is 10dB higher than at 7MHz, and it increases linearly with frequency.
This led to some theories about the root cause, although it's hard to really determine which one of those is correct, especially with limited test equipment (and even then...). A good night sleep is probably not a bad start...

Greetings,
Hans.
73,
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Re: Peaberry help

Postby AE9RB » Sat May 04, 2013 12:10 am

If you need more sensitivity, remove C18 and C19 then increase R10 and R11 to 10k. C18 and C19 can be permanently left off the radio to no effect which leaves you free to experiment with R10 and R11.

Of course, a better antenna is always better than more preamp!

You're probably seeing the effect of a constant phase noise on increasing frequency. All the popular projects seemed to use a single sided receiver design so that's what I put in V1. V2 uses a double balanced mixer which does a better job of rejecting the phase noise.
73 David AE9RB
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Re: Peaberry help

Postby hansvi » Sat May 04, 2013 3:46 pm

Thanks for the feedback.

It's probably a combination of factors indeed; I lose a few dB signal because the antenna is more suited for 40 and 80m, I gain a few dB noise, and before you know it, the signal is gone.

As luck would have it, soon I'll be putting together a V2 (the peaberry, not the weapon). So I'm thinking more in the direction of moving towards 80/40 with the V1, and using the V2 for the higher frequencies. But I still have time to think about that.
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