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PostPosted: Mon Sep 07, 2015 7:07 pm 
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Joined: Mon Jul 23, 2012 6:25 am
Posts: 1143
Well I found out a few more things. The way the circuit works the gate voltage is about 1/2 the applied voltage. I think that it has something to do with the way they temperature compensate the part. So I replaced the logic gate drive with a fixed 5.1V from a zener and I could get a little more power form 20 dBm, 39 dBm on 2m and 220 and 34 dBm on 450. I havent run it at 900 but I'll try and see what it does. It might als be useful to know what it does at 10M, 6M and 4M as well.

I also found out that when you activate the shutdown on a boost regulator, the output voltage doesn't go to 0, it goes to the input voltage. So when I unkey the amp Vdd drops to 13.8V but the Idd stays the same if I don't switch off the bias. Also switching from 12 to 25V with the bias on can destroy the amp.

So I'm done testing until I can rig up a 7V switched bias... I popped two MW7IC008's before I figured it out. May have to do a Kick-Starter campaign if this keeps up.

73,
Jim WA2EUJ


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PostPosted: Thu Oct 27, 2016 8:06 pm 
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Joined: Fri Sep 04, 2015 7:31 am
Posts: 17
LimeSDR's going to be shipping some time next month .. people are going to need band pass filters ...

Id like to see those 2m, 1.25m and 70cm filters for sale ... even if not on the web site ...

even 902mhz and 1.2ghz ... 2.4ghz anyone ?


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PostPosted: Fri Oct 28, 2016 7:52 am 
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Joined: Mon Jul 23, 2012 6:25 am
Posts: 1143
We still have a few of each of the 144, 220, 440 filters in stock but with the website hack and getting ready for the KickStart campaign we haven't got them up yet.

Higher bands would need better PCB material than FR4 which would make them more expensive. The 902 and 2.4 should be easy to fine COTS filters. The MiniCircuits VBFZ-925-S+ is $40 in single quantities and the VBF-2435+ is only $35. They don't really have anything for 1.2 though.


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