Saturday, January 23, 2016

HT Harmonic Output Testing

Originally posted in 2015, but presented here also.

There has been a lot of discussion recently on how bad the "Chinese Radios" are about suppressing harmonic output.

I had access to a spectrum analyzer as well as a few different HTs, so I figured I'd test a few.

The units I tested were (prices approx at time of writing)

Icom ID-51A+         ($360)
Yaesu FT-1DR         ($270)
Kenwood TH-F6A    ($320)
Wouxun KG-UV8D   ($110)
Wouxun KG-UV3D   ($99)
Baofeng UV-5R       ($30)

The relevant section of the Part 97 rules states:

§97.307 Emission standards.

(e) The mean power of any spurious emission from a station transmitter or external RF power amplifier transmitting on a frequency between 30- 225 MHz must be at least 60 dB below the mean power of the fundamental. For a transmitter having a mean power of 25 W or less, the mean power of any spurious emission supplied to the antenna transmission line must not exceed 25 µW and must be at least 40 dB below the mean power of the fundamental emission, but need not be reduced below the power of 10 µW. A transmitter built before April 15, 1977, or first marketed before January 1, 1978, is exempt from this requirement. 

For a handheld transmitter with an output of 5W (+37 dBm), the spurious emission must be below 25 µW (-16 dBm)

tl:dr ("Too Long, Didn't Read") 
  • The Big Three manufacturers pass well.
  • Wouxun do an admirable job for the price of the hardware. 
  • The Baofeng UV-5R is in violation of Part 97 and should not be used.

An external 30 dB of attenuation was added to the input port of the spectrum analyzer to prevent damage. The 30.0 dB Ext Loss on the plots below show that this offset was added to the measurements. The green line on the plots is at -16 dBm, which as stated is the FCC limit for spurious emissions.

Icom ID-51A+
2 m and 70 cm both look great, nothing notable above -30 dBm (1 µW)
ID-52A 2m
ID-51A 70 cm

Yaesu FT-1DR
2 m and 70 cm both look great, nothing notable above -30 dBm (1 µW)

Kenwood TH-F6A
2 m and 70 cm both look great, nothing notable above -30 dBm (1 µW)

Wouxun KG-UV8D
2 m and 70 cm both look great, nothing notable above -30 dBm (1 µW)

Wouxun KG-UV3D
2 m looks great, nothing noteable above -30 dBm (1 µW)
70 cm first harmonic beginning to creep up, but still 10 dB of magin. I'd call this good

Baofeng UV-5R
The popular $30 HT that is recommended by many to new licencees.

2 m has the first 3 harmonics failing quite drastically. Also has some sub-harmonics that whilst not failing, are not pretty.
70 cm has the first 2 harmonics very close to (if not over) the spec line

The radios from "The Big Three" (YaeComWood) all performed admirably, as you might expect. After all these radios do all cost over $300.

The Wouxun radios tested both performed pretty well - the new KG-UV8D was no different from the YaeComWood units on the plots taken. It's older cousin, the KG-UV3D had a visible harmonic, but still had plenty of magin.

The Boafeng UV-5R, well let's just say if you key up on 2m you are violating the Part 97 rules you promise to upkeep. On 70cm, the data I took was close enough to the limit line that more data should be taken. However, my 3 UV-5R units are destined for the e-waste bin.