Re: ARLA/CLUSTER: Novos testes aos equipamentos pelos Laboratórios da ARRL em Outubro.

[Carlos Mourato]

Hummmm!!!!..Acho que fiz uma boa escolha, ao comprar esse IC7200, igualinho
ao da foto!...Com pegas e tudo!!!..Foi por causa desses numeros que aparecem
aí e pelo aspecto militar, que eu me decidi!!!!...Até agora considero a
escuta do 7200 comparável, senão mesmo melhor do que a do FT1000 MPMKV. pena
não ter FM para "reinar" um pouco nos 10m!..
73 de CT4RK


2009/9/21 João Gonçalves Costa <joao.a.costa  ctt.pt>

>  New product review tests to begin in October QST
>
> When you peruse the October issue of *QST*, you may notice a few extra
> lines in the Product Review data.
>
> "Here at the ARRL Lab, we strive to make our test procedures relevant to
> current technology and to new
> features common on today's transceivers," said ARRL Test Engineer *Bob
> Allison, WB1GCM*.
>
> "We continue to research ways to improve our testing and to develop new
> tests that will benefit our members. I hope you will find these new
> measurements useful in evaluating and comparing transceivers."
>
> ** Receiver Sensitivity (MDS) at 137 and 505 kHz*
> Several countries now give amateurs permission to operate at and around 137
> and 505 kHz. In the US, there is activity on 495 to 510 kHz by more than 20
> stations around the country operating under the ARRL sponsored WD2XSH
> experimental license. In addition, there are other Part 15
> experimental licensees operating in this range. The WD2XSH stations are on
> the air regularly, gathering propagation data. They are always looking for
> signal reports.
>
> Allison said that with many of today's transceivers and a suitable antenna,
> you can listen for these experimental stations and submit reception reports
> via the Web site: "The new Product Review tests will help identify
> transceivers suitable for use on these frequencies. With equipment built
> over the last 25 years ago or so, I've noticed a wide variety of available
> sensitivity, from terrible to quite good. Many
> receivers tune to 137 and 505 kHz; not all are proficient at receiving
> signals there. For you 'lowfers,' this measurement is for you."
>
> ** Spectral Sensitivity*
> Spectral sensitivity is the weakest signal that can be "seen" on a visual
> display of spectrum above and below the operating frequency. Often called a
> spectrum scope or panadapter, this feature is included on many mid-range and
> high-end transceivers. "This data represents the level, in dBm, at which the
> operator can see a signal poke up out of the display noise floor," Allison
> explained.
>
> "Although the measurement is somewhat subjective, it works out to be about
> 3 dB above the noise floor at the bottom of the display when the scope is
> adjusted to show 100 kHz of spectrum. With software-defined receivers
> (SDRs), such as the FLEX-3000, the sample rate is set to the highest
> setting."
>
> ** Audio Output THD at 1 V RMS*
> Allison said that one of the ARRL Technical Advisors posed the question,
> "Who ever listens to their receiver at full volume?" Allison explained that
> audio output power and THD (total harmonic distortion) at the specified load
> impedances as specified by the manufacturer have been tested and reported.
>
> "Generally, the specification is at or near the maximum audio output the
> receiver is capable of," he said. "If severe hearing loss isn't an issue, we
> normally listen with the volume control set to around the 9 o'clock to 11
> o'clock position on most transceivers and not with the control cranked to
> maximum."
>
> Allison explained that distortion at normal listening levels is an
> important factor, especially when you are listening for an extended period
> of time: "High levels of distortion can make signals more difficult to
> understand and add to fatigue. We'll continue to measure and report how
> audio output power and THD compare to manufacturers' specifications, but we
> have added a new test intended to show distortion
> at more typical volume levels."
>
> After testing several radios for comfort, Allison picked 1 V RMS as an
> output level for the new test. "It's an easy figure to remember," he said.
> "We will now also report THD at this level. Note that this test will appear
> with the next transceiver reviewed because the FLEX-3000 has only a
> low-level audio output and is dependent on external, user-supplied devices
> to amplify the audio to normal listening levels."
>
> Look for these new tests beginning with October's QST Product Review
> featuring the FLEX-3000.
>
> Fonte: The American Radio Relay League <http://www.arrl.org/>
>
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>
>


-- 
Best 73 from: regards from: CT4RK Carlos Mourato - Sines - Portugal

Save the Radio Spectrum! Eliminate Broadband over Power Line. Salve o
espectro electromagnético!. Não use a rede electrica para transmitir dados.
Os "homeplugs power line" e a tecnologia "power line" causa fortes
interferencias noutro serviços sem voce se aperceber. Diga não à tecnologia
power line. Proteja o ambiente
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