U14 Pin 3 Voltage 1.4V

General discussion and support for the Peaberry SDR V2.

U14 Pin 3 Voltage 1.4V

Postby ka8kpn » Sat Feb 14, 2015 9:26 pm

I installed the Si570 and R14, R48, and R49 and my oscilloscope shows a square-ish wave at 56.3 MHz at 1.4V peak-to-peak. What should I check next?
ka8kpn
 
Posts: 6
Joined: Sat Feb 14, 2015 9:22 pm

Re: U14 Pin 3 Voltage 1.4V

Postby AE9RB » Sat Feb 14, 2015 9:55 pm

Maybe the Si570 is not getting a full 3.3V on Vcc. Go back and check the voltage regulators. Or maybe it's a wrong setting on your scope. Try the multimeter test here.
73 David AE9RB
AE9RB
Site Admin
 
Posts: 511
Joined: Thu Nov 15, 2012 5:27 am
Location: Portland, Oregon, USA (CN85ql)

Re: U14 Pin 3 Voltage 1.4V

Postby ka8kpn » Sun Feb 15, 2015 6:03 pm

When I try to do the multimeter test instead of using the scope, I don't get sensible readings. (I know it's not 24 volts.) I can confirm that I'm 1V/division on my cheap Chinese scope. With DC coupling, I see that the wave goes from 0.9V to 2.4V with an average of about 1.6V, which is what I'd expect if it's working. The scope is supposed to have a 100MHz bandwidth. Do you think maybe it's the cheap probes or something? I suppose I could take it in to work because we've got some test gear with ungodly bandwidths.

The multimeter does say that the output of the 3.3V regulator is at 3.3V and the output of both of the 5V regulators are at 5V.

The question is whether or not I should continue with the assembly. I'm thinking I probably should. I think that it probably is working fine, but it's not something my equipment can readily test.
ka8kpn
 
Posts: 6
Joined: Sat Feb 14, 2015 9:22 pm


Return to Peaberry SDR V2

Who is online

Users browsing this forum: No registered users and 3 guests

cron