Baofeng RD-5R, Dirty HT

Discussion in 'Amateur Radio Equipment Reviews' started by KU3X, Oct 22, 2018.

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  1. KU3X

    KU3X Ham Member QRZ Page

    Baofeng has again come out with an HT that also covers DMR. The old UV-5R did not meet FCC requirements of spurious harmonics being down 60 DB for frequencies above 30 mhz.
    The new Baofeng Professional ( I like that. PROFESSIONAL -RIGHT !) RD-5R is just as bad as the old UV-5R.

    The DR-5R does not meet meet FCC requirements. So keep in mind, "Every time you transmit with one of these you are in violation of the FCC rules here in the USA."

    Barry, KU3X
     

    Attached Files:

    Last edited: Oct 22, 2018
  2. AA5CT

    AA5CT Ham Member QRZ Page

    How did you measure that? Did you attenuate the fundamental, the 2m "carrier"?

    It shows -3.89 dBm in the Peak Table, so I'm thinking you did not notch the fundamental at 145.6333 MHz ... what is the "dynamic range" spec on the Rigol spec an?

    Anytime in the past that we measured harmonic energy "for real" we would notch the fundamental frequency such that we were _not_ near the dynamic range of the spectrum analyzer used to make that measurement.

    Also, did you have any sort of wattmeter inline? Sometimes the diode detectors can create harmonics that are seen 50 some dB down depending on the type and design.

    Need to know the test setup, value of inline attenuators, test procedure.
     
  3. AA5CT

    AA5CT Ham Member QRZ Page

  4. ND5Y

    ND5Y Ham Member QRZ Page

    Testing a cheap chinese radio with a cheap chinese spectrum analyzer. What coud possibly go wrong?
     
  5. KA9JLM

    KA9JLM Ham Member QRZ Page

    I can see the reason for a attenuator, But why the filter when you want to measure all garbage from the radio ?

    Don't sound right to use any filter. Unless you use it in normal operation.

    Using a filter can make any radio pass.
     
    Last edited: Nov 27, 2018
  6. AA5CT

    AA5CT Ham Member QRZ Page

    Think about it. Well, wait, maybe you have ....

    Maybe you are new to electronics, and wireless comms/ RF engineering in particular?

    BTW, that is not MY recommendation, it is ONLY the recommendation of EVERY vendor of spec ans AND every "standards body" (whose responsibility is overseeing standards for spurious and harmonic emissions.

    Maybe you don't understand the physics of solid state devices, what the limitations are on building a front-end wideband mixer, and the challenge that presents in achieving, oh, say over 60 dB of dynamic range in a piece of mass-produced equipment.

    People like Rohde and Schwartz specify the use of filters, as shown in the paper "1EF78_2E.pdf " found here:
    https://www.rohde-schwarz.com/us/ap...m-analyzers-application-note_56280-15467.html

    Motorola specifies the use of filters for measuring harmonics too:
    https://fccid.io/AZ492FT4829/Test-Report/Test-Sepup-Procedures-58415

    A fellow hobbyist discusses his travails in measuring harmonic energy in this post, and describes his use of a filter:
    http://www.amalgamate2000.com/radio-hobbies/radio/measuring_second_harmonic_level_.htm

    Now, given all that, and the previous reference in the book on practical spec an use, maybe I've filled in some of the dark crevices on this subject.

    Oh - and another reference that sites using a filter preceding the spec an, to notch the fundamental, such that the actual harmonic energy may be measured, and not just the limited 'dynamic range' of the spec an:
    https://www.ofca.gov.hk/filemanager/ofca/en/content_401/hkta1046.pdf
     
  7. KA9JLM

    KA9JLM Ham Member QRZ Page

    Sounds good. But all transmitter trash may not be on a harmonic.

    Thank You for the great info. :)
     
  8. KV6O

    KV6O Ham Member QRZ Page

    Besides the questions as to your test setup, and steps taken to test if the harmonics were SA mixer generated, the FCC rules on the matter (47 CFR Part 97 Section 97.307(e)) state:

    (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. - https://www.gpo.gov/fdsys/pkg/CFR-2011-title47-vol5/pdf/CFR-2011-title47-vol5-sec97-307.pdf

    By your own measurement (without further attenuation padding info), the radio passes.
     
  9. KU3X

    KU3X Ham Member QRZ Page


    When I'm wrong, I am wrong! I based my test on the 60 db down as a blanket rule. I did not realize that the rule was different for a power level of 25 watts or less....and now I know.

    2018 ARRL Handbook Page 27.8

    So sorry to all !

    Barry G. Kery, KU3X
     
    KA9JLM likes this.
  10. KV6O

    KV6O Ham Member QRZ Page

    No worries! Not knowing what attenuation you were using, we can't determine the absolute power on the spurious emissions - there might still be an issue with the 25uW spec. But in a practical matter, 25uW into a dummy load for an antenna (which is what they ship with) isn't much of a menace to the airwaves...

    The other question I thought if is the issue of MEAN power. If you're running in DMR TDMA mode, the mean power should be around 1/2 the peak, or 2.5W for a 5W radio. That might buy you another 3db or so on the measurement.
     

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