James,
If we were speaking about radios in general, and all radios ever built, then
your statement would be technically correct.
But since we are listing radios here which are touted to be among the top
amateur transceivers available, then it basically all boils down to weak
signal performance in the presence of many strong signals on neighboring
channels. NO receiver with upward conversion is in the league here with the
good radios with downward conversion. There will be a least 10 to 15 dB
difference.
An upward conversion loses out EVERY TIME because it is not possible to
build Xtal filters on the high IF frequencies with attenuation slopes as
steep as you can with filters on much lower frequencies. It has to do with
the fractional bandwidth of the filter.
Therefore I state once again that the downward conversion gives superior
performance on the ham bands, by (in general) 15dB or better.
NOW I DID MAKE ONE MISTAKE:
I put the FT-3000 in the class with upward conversion second receivers.
Well it does not even have a second RX. It only has one. My mistake. So
it belongs in the group just below, with all the Icoms. However what it
does have is inferior performance like most rigs with upward conversion. So
this shows that your statement is also partly correct, but not in a positive
way. If you don't get all your ducks lined up properly, even a radio with
downward conversion will not be a top performer, despite its "Heritage"
(hi). In the case of the FT-3000, it is the cheap, noisy synthesizer that
degrades performance.
FINALLY, the Orion's second receiver has already been indirectly compared to
the RX366. Long ago Rob Sherwood compared the performance of the Orion's
second RX to its first RX. We'll have to look back in some old files to
find the exact numbers, but the first RX was significantly better. If I
recall correctly, about 15dB better BDR3 with close spacing.
Since the RX366'sis roughly the same as the Orion's first RX, then it is
clear that it is also significantly better on the ham bands than the
original 2nd RX in the Orion.
73
Rick, DJ0IP
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Richards
Sent: Sunday, May 19, 2013 4:09 AM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] RX366
On 5/18/2013 6:12 PM, Rick - DJ0IP / NJ0IP wrote:
> WELL DONE, BARRY!
>
> Let's see, what have we learned from this?
>
> "Radios with a 2nd RX using upward conversion won't work as well on
> the ham bands as receivers using downward conversion!"
Er... um... Not necessarily.
That would be true only if the upward - downward
conversion was the only difference in the two
receivers. If there are other differences in
the two receivers, it could be some of those
other differences, or the combination of all
differences, makes one better. Unless the
conversion direction is the only difference,
you cannot just say that is the only reason
one might work better than the other.
This is, at least, one logical construct.
> Hmmmm, seems I remember a few other radios whose 1st RX uses downward
> conversion, but 2nd RX uses upward conversion:
You left out the TS-590s, which uses down conversion
on some bands as long as your DSP bandwidth is
2700 Hz or less.
> <> Yaesu FT-5000
> <> Yaesu FT-3000
> <> Kenwood TS-990 (uses it on WARC bands + 15 and 10m)
>
> Ten-Tec has one big problem . . . and Randy Dangerfield described it:
> "I can't get no respect!"
Rodney, Ol' man... Rodney...
He gets so little respect nobody can
remember his name !!! ;-)
But the thought is what counts !!!!!
> Maybe that will improve with the Rebel.
> The "open" design is out of this world . . .
> As in "One small step for a man, one giant step . . ."
Too cute. ;-)
> *VERY* WELL DONE, TEN-TEC!
Regardless of how the Rebel thing does
in the market place, it is a bold step
in a fresh, new and timely direction.
AT least they are stoking an active fire.
======================= JHR ====================
/
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