[UK-CONTEST] Amplifier Advice ACOM 2000's

[Don Field]

Interesting comment about  "inadequate close-in dynamic range" etc. for
radios like the 817/857/897.  Arguably, those radios are eminently fit for
purpose, but are too often used for purposes for which they were never
designed or intended. I well recall the editor of the Japanese CQ magazine,
who I met some years ago at Visalia, commenting on how surprising it was
that so many European amateurs insisted on using mobile radios for base
station use. These radios were designed for the large mobile market in
Japan - it is huge, as so many JA hams are unable to operate from home (big
apartment blocks in cities like Tokyo). The radios therefore have high
sensitivity but, almost by definition, will cave in when put on a home
station antenna.

Unfortunately, European dealers tend not to make this clear - they are more
interested in shifting kit and not everyone can afford a hi-spec base
station transceiver.

The good news is that, with improved RF devices and DSP chips, even the
cheaper, smaller radios nowadays are showing better and better performance.

Don G3XTT


On 26 January 2012 11:07, David <g3yyd at btinternet.com> wrote:

> Ian
>
> I agree with you also about RX performance. I would not like to be running
> a
> FT857 in a major contest (I use one in the car) its close in performance is
> terrible makes a perfect transmission a wide one due to its inadequate
> dynamic range. Many RXs in use are of similar inadequate performance to the
> FT817/FT857/897 series in a strong signal environment. Even the FT1000MP
> has
> inadequate close in dynamic range and in RTTY and CW contests I used to
> hear
> phantom signals created by intermodulation products of multiple contest
> signals.
>
> It is for this reason that a significant number of major contesters now use
> the Elecraft K3. If you hear a wide signal on a K3 it is the TX that is the
> problem. Also the K3 PA IMD is around -40dB below PEP at 100 watts and
> lower
> at 40-50 watts. Most popular rigs are -30dB or worse.
>
> The cause of wide signals using FSK is inadequate filtering of the TX
> signal.
>
> 73 David
>
>