Rick Wrote:
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Date: Mon, 12 Sep 2016 09:26:30 +0200
From: "rick@dj0ip.de" <Rick@DJ0IP.de>
To: "'Discussion of Ten-Tec Equipment'" <tentec@contesting.com>
Subject: Re: [TenTec] Scads of used Icom IC-7300
Message-ID: <000e01d20cc6$fc534820$f4f9d860$@de>
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FLEX 6500 vs 7300
1. The 6500 has dedicated ham band BPFs for each band, the 7300 does not.
2. The stage gain of the 7300 was not designed specifically for the needs
of an SDR but rather just copied off of the (analog) 7100.
3. There is a problem with the 7300 that when you switch on IP+ which adds
the dither, it also raises the noise floor by 10 dB. That should not
happen.
4. The 6500 costs about 3x as much, has been on the market longer and many
bugs have already been fixed.
73 - Rick, DJ0IP
(Nr. Frankfurt, Germany)
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1. The 7300 has band pass filters. A boat load of them. The 40m band falls
inside a 1.5MHz wide BPF. "Outboard pre-selector" is not a dirty phrase.
(See Lenny Bruce 'words')
2. With the pre-amp off, there is no amplification between the antenna and
the A/D.
3. Dither is there to allow digitization of a signal that is of the order
of a LSB. It's appropriate for weak signals on a very quiet band. 10dB is a
reasonable amount of noise to be adding to accomplish this.
4. More bugs require more fixes ;-)
In the $1500 and lower price range for 100W radios, I only see three worth
having. right now. Eagle, TS590SG,, IC7300.
A quick aside to "scads". The scads of 7300's on QRZ. There people are
posting WTB 7300 and radios offered at $1300 are selling quickly
I predict we will soon be comparing DDC receivers based clock stability,
processing speed, and linear signal handling capacity of the passive
components preceeding the A/D. Ferrites in filters, PIN diodes, that sort
of thing. An outboard, high Q, pre-selector can be a big help with overload
with almost any receiver. For the rich guys we can makes it a 'tracking'
pre-selector so they do not have to be bothered turning a knob.
The trade off in using a pre-selector as opposed to a band wide filter is
that one can not see the entire post filter band at once. Sometimes two
radios make more sense.
Reference:
https://www.dropbox.com/s/58rh4i19rmwkuim/IC-7300_Schematic_Diagram.pdf
Some more prediction. Multiple receivers that are phase coherent coupled
with receive only antenna arrays to transfer the signals into 2 and
eventually 3-D at the operators ears. Instead of turning a beam or
struggling to dig out of the noise with a vertical, one would just turn his
head to hear signals arriving from a different direction or to ignore noise.
I'm actually considering a pair of vertical with $22 softrocks and a
phasing knob in the shack. A problem with the soft rocks is that even with
the same clock, they won't necessarily start up in the same phase. My
cheap-O solution to this is a calibration signal for the control knob.
73, -Bob
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