[Amps] Pre-Distortion Linearizer

[Roger (K8RI)]

On 5/5/2013 3:47 AM, Ian White wrote:
>
> You have a point, Joe; both transmitters and receivers fall into
> different classes of performance depending on the price range. But there
> is still no valid reason for any transceiver to perform significantly
> worse than the comparable "best in class".
>
> Stepping up to a completely different performance class does indeed cost
> money; but improving performance to equal the "best in class" is much
> more often about attention to detail.
>
> Because there has been such a market-driven obsession with "receiver
> numbers" like IP3, the best designers in the development team are
> working on the receivers, while the design of the transmitter is
> apparently being left to the tea boy. There is a real lack of managerial
> - and indeed, moral - imperative to design the best possible transmitter
> that can be produced within the given budget.
>
> Another aspect of the "$900 rig problem" is that most of these
> transceivers were originally designed for the domestic market in Japan,
> which is much more heavily biased towards mobile operation due to the
> population density. Many aspects of performance are sacrificed for the
> sake of compactness as well as low cost; but in addition to that, they
> are specifically designed for operation with relatively inefficient
> mobile antennas. That means the receiver needs to be quite sensitive and
> the transmitted IMD will be 6-10dB further into the noise. But when the
> same radio is used at a fixed station with even a simple wire antenna,
> the receiver becomes overly sensitive and has poor strong-signal
> handling, while the transmitted IMD looks very poor indeed.
>
> Some years ago, the Japanese manufacturers were quite surprised that
> what they thought of as "mobile" transceivers were being marketed in the
> West for fixed-station use; but now these $900 rigs have become a major
> part of the Western market. Beginners reasonably ask why they should pay
> more... and I don't think that anyone is telling them.
>
>
> 73 from Ian GM3SEK
>
>
>> -----Original Message-----
>> From: Joe Subich, W4TV [mailto:lists at subich.com]
>> Sent: 04 May 2013 15:36
>> To: Colin Lamb
>> Cc: Ian White; amps at contesting.com
>> Subject: Re: [Amps] Pre-Distortion Linearizer
>>
>>
>> On 5/4/2013 9:37 AM, Colin Lamb wrote:
>>> The breakthrough may be when one manufacturer begins marketing their
>>> low end transceiver with a -35 db IMD rather than a -25 db one.  That
>>> would give a distinct marketing advantage.
>>
>> The problem is that manufacturers are not going to be able to produce a
>> "low end transceiver" - at least at the low end price point - that has
> all the

You are ignoring what I see as probably the most likely reason for the 
performance difference versus price and that is sales/performance are 
driven by marketing rather than engineering.

Marketing in large corporations normally equates price vs performance 
and having low end performance equal high end performance is anathema to 
marketing.  Instead of just having fewer features, both performance and 
construction suffer at the low cost end for those producing a wide price 
range.  Take a 897D apart and compare the construction to an FTDX5000. 
Look at the jacks and how they are attached as a start.

Yes I would openly accuse all of the large manufacturers of this even if 
-35 db 3rd order IM is not possible at 11 volts.

I agree with your conclusions below, but think the marketing aspect is 
still primary at least for anything other than the $900 rig and 
marketing is still the reason for that $900 rig.

For those willing to settle for other than new there are much better 
rigs available, but they will likely be a bit more than $900 and they 
likely will still be hobbled with the lower voltage finals. Actually, I 
saw a beautiful KWM2A (Round emblem with PS) go for around $1200 last 
week. Wish I'd bid on it.

73

Roger (K8RI)


>> features demanded by the marketplace.  The technology simply does not
>> exist to make a broadband (no tune), 100W output amplifier that runs on
>> 11V (low end of a battery life) and achieve -35 dB in the final and do
> it for
>> even 10% more than the current crop of $900 rigs.
>> Add other requirements like reasonably clean phase noise performance,
>> acceptable (~80 dB) 2 KHz receive IMD, and acceptable ~100 dB) blocking
>> dynamic range and it is simply not possible from a cost perspective.
>>
>> $900 rigs are there for a reason ... that's all that many amateurs will
> pay.
>>
>> 73,
>>
>>      ... Joe, W4TV
>
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