Baofeng UV-5R test

[Golay]

So ever since the Bullfrog 5R has come out, people say it can do spurious emissions, or transmit where it don't say it is at. Lacking a large potpourri of testing equipment, I do have a Tenma handheld frequency counter that goes up to 1.3 GHz. Laboratory grade it is not. So the thought crossed my mind to watch the radio on the frequency counter. It was rock solid on the simplex freq I was keying up. Did it about a dozen times. Never wavered, never bounced around at any time.

In your opinion, do you think I have eliminated the possibility of this radio being out of compliance?

 

[nd5y]

No. A frequency counter will not show spurs or harmonics.

 

[jonwienke]

No. A frequency counter only looks at the main frequency output. It does not tell you if it is also emitting multiples of the nominal TX frequency.

For example, if you are TXing at 145MHz, your radio may also be emitting RF at 290MHz (145 x 2) or 435MHz (145 x 3) and/or other multiples of the TX frequency Every radio does this to some extent, but there are limits to how much such spurious emission is allowed. You need a spectrum analyzer that can measure frequencies up to about 10x the TX frequency to really see what the radio is doing.

In practice, even if the radio has out-of-spec spurious emission, it's unlikely to be a problem unless you are connecting the HT to a power amp. If it had a -20dB spike at 3x the TX frequency (which would be >10dB out-of-spec), that spike would have 50 milliwatts of power. That level of RF power coming out of a HT antenna is going to have a detectable range measured in yards--that's the same power output as the old 49MHz toy walkie-talkies that ran on 9V batteries. It's theoretically possible that could interfere with something, but pretty unlikely.

Now when you up the power of the radio, the spurious emissions become more significant. A -20dB emission from a 50W radio is 500mW, which is the same as your bubble-pack FRS radios.