That is kind of correct.
It has a receiver preselector, but it is not like those we are accustomed to
in our ham band transceivers.
We hams expect a dedicated preselector (bandpass filter) per band, just
slightly wider than the ham band.
The 6300 has several BPFs in its front end but they are all several MHz
wide.
So it basically is a barn door, open wide.
The problem is, there are commercial applications (and Government
applications) conflicting with our ham band applications.
We are generally interested in listening within our own bands and we want to
reject everything outside of it. The other guys often want to monitor
several MHz of frequency at once and a BPF would be detrimental. In order
to please both worlds, you would need filters for both applications. This
is only available in the more expensive version (i.e. 6500 and 6700), but
not in the entry level 6300.
This is an age old problem.
All the way back in the 1950's and 60's, OEMs such as National and
Hallicrafters were faced with this problem... shall we optimize for ham band
only or for general coverage (GC)? As a result they often built two models
of each receiver design, a GC and a Ham-Band-Only. Obviously the
ham-band-only was better for our use but we didn't have GC.
Throughout the late 1960's and 1970s, our hybrid transceivers were all
ham-band-only.
They all used downward [IF] conversion.
About 1980 saw the emergence of ham radio transceivers with GC receivers
within. In order to accomplish this, they switched to upward conversion
(i.e. IF usually 45 MHz or higher).
The result was a 3rd order dynamic range about 20dB worse than the previous
generation of transceivers... but nobody knew it.... except perhaps Ten-Tec
who refused to go down that detour street. The Corsair and Omni V and VI
continued to be ham-band-only with downward conversion ande were much better
than all of the JA radios, especially with our European problem with
shortwave broadcast stations.
With the Orion the term roofing filter was introduced and the world once
again became aware of the virtue (for us hams) in downward conversion. The
past 10 years has seen all JA brands except for Icom migrate back to
downward conversion.
Then the SDR (direct conversion, not heterodyning like the Orion) came onto
the market and the world immediately jumped on its ability to receive a
broad frequency range simultaneously. This new feature apparently fogged
over the eyes of most hams. Though they saw merit in the ability to have a
broadband receiver and display, then failed to realize that once again they
were compromising ham band performance.
All of that translated into plain vanilla English: Seems we still can't
have our cake and eat it too. Unless we're willing to spend a lot of money,
we're going to have to accept compromise (i.e. ham-band only instead of
broadband - or broadband with lesser performance instead of ham-band-only).
What we need: direct conversion from hf to baseband (af) but with darn good
ham-band bandpass filtering... in our first RX, and then a second RX with a
wide BPF for monitoring multiple MHz.
73 - Rick, DJ0IP
(Nr. Frankfurt, Germany)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of terry
foskey via TenTec
Sent: Friday, April 29, 2016 10:37 PM
To: tentec@contesting.com
Cc: terry foskey
Subject: [TenTec] Sherwood Reports
I had a Flex 6300, one thing that I didn't like the idea of was it had a
different receiver front end than that of 6500 and above...seems like I
recall it had no preselector, never tried it in a heavy RF environment but
it would be interesting to evaluate in a contest station environment or
Europe.
Terry
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