There are *NO* hardware mods to the transmit section of my rig (TS-950SDX)
whatsoever. It will allow me to select its 6k IF filter for TX, and the 4k BW
is SW limited in the DSP. If I had an external DSP unit, I could transmit 6k
of SSB. Which, by the way, is a phasing method of SSB generation -- extremely
clean. The Kenwood TS-850 with its external DSP-100 is an example of a rig
that can also do that, and at 6k. The Flex Radio can transmit full Hi-Fi
(20-20k), but nobody does that. Why would anyone? Your logic assumes the
worst case scenario, which is not the case. I can legally home-brew a rig (AM
or SSB for that matter) that would do whatever BW I choose today. As can
anyone, yet nobody does. In fact, I know a couple guys using converted AM
broadcast transmitters on AM that have purposely limited their audio BW. Why
do you think that is?
There is no verbage in Part 97 remotely resembling the term "Toll Quality" in
terms of SSB or AM BW. We are allowed any SSB BW that we deem as "necessary",
and I say it's 4k. Others say 6k, band loading conditions permitting.
Trashing the band with harmonics and spurious is already against the rules. So
is 2k of SSB if you plop yourself down too close to an ongoing QSO. So, I ask
again -- what is your logical reason for limiting Amateur Radio BW to 3k? And
what does that buy us?
Joe, N3JI
----- Original Message ----
From: "Joe Subich, W4TV" <w4tv@subich.com>
To: Joe Isabella <n3ji@yahoo.com>; amps@contesting.com
Sent: Monday, July 3, 2006 11:23:33 AM
Subject: RE: [Amps] Maximum RF output in practical application: 4-250A
N3JI writes:
> Really Joe?? So how many rigs do you have with an "ISB" button?
> None of mine do. It does however have an AM button, as well as
> 4k+ (at -6dB) of SSB right out of the box.
Modern radios will only do 4K+ of SSB if you bypass the if filter
which is generally 2.7 to 3.0 KHz wide at the - 6dB point or use
outboard equalization techniques to "make up" for the losses on
both filter skirts. Both techniques are bad engineering practice
and can result in additional distortion and/or interference to
adjacent users.
> The justification for BW greater than 3k is exactly the reason
> you stated -- this is Amateur Radio, and we should be free to
> experiment as such.
Nonsense ... that argument would have amateur radio returning to
unfiltered and unshaped spark signals. The rules already call for
using no more bandwidth that necessary ... for voice circuits that
bandwidth is "toll grade" audio.
> That said, mis-tuned amps, slamming ALCs, etc. (in other words, a
> lot of contesters & DX'ers) should be admonished for their operating
> behavior, as well as anyone else that thinks "all knobs & meters
> to the right" is the way to operate.
I'm not defending the "all knobs to the right" crowd. Their behavior
is also wrong.
> In other words, "Good audio is an Amateur Radio Tradition, not a
> Crime" (borrowed tag line from another Amateur).
There is nothing wrong with good (clean) audio. However, those
who bypass or replace 2.7 KHz filters with 4 to 6 KHz filters or
preemphasize audio into the microphone input of a rig in order to
generate SSB signals from 4 to 6 KHz wide or 10 KHZ+ wide AM
signals are "passing gas" in church.
73,
... Joe, W4TV
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