WSRP - 2nd U3s finished

I've finished my second U3s.


IMG 0567 IMG 0544 IMG 0545

Again in the sturdy professional BOPLA ULTRAMAS case. The DC voltage regulators are simply LM317 based ones.

The PA in this U3s is running with 9VD and features the bifilar output transformer in the PA. In this U3s I've added two PA FETs which results in this output:

Band Power Power
10m 24dBm 251mW
15m 25dBm 316mW
20m 24dBm 251mW
30m 25dBm 316mW
40m 26dBm 398mW
60m 29dBm 794mW
80m 30dBm 1000mW


I assume the low power on the upper bands is due to the gate capacity of the BS170 FET.