Radio Society of Greater Bixby

We were going to compare RX sensitivity on Chinese H/Ts, but instead, we spent most of the hour measuring TX output and using a Spectrum Analyzer (Tiny SA on Ebay for $68) to check for spurious output. Shown above is an anomaly, second, third, and fourth harmonics that weren’t there.

Two Baofeng UV5Rs (the x3 model) measured 5.3 and 5.4 Watts out on 220. That’s good. They were bought about a year ago on EBay. Deb and Sam, DBE and BJR, both had Baofeng UV25s that output at stated ratings.

Every transmitter has a Low Pass filter on the output to restrict spurious at higher freqs. FCC spec is a 40 dB reduction. Deb DBE’s TID Radio H8 showed the second harmonic at negative 50 dB, similar to Mike KI5YX’s Japanese HT at negative 53.

Rich ZQG related a story from the beginning of WWII how Leo W0GFQ and friends were able to mass produce crystals for Army tank radios, their first contract spec 60,000 xtals in a few months from a small town (Council Bluffs) in Iowa that enabled our guys to communicate faster and more easily than the opposition using tunable radios. Their secret technique was not allowed to be kept secret back then so other Americans were later able to do the same.