Hi all. Very interesting "thinking out loud" topic.
With regards to the 403 crystal front end unit system (it seems not yet
available), it will obviously be quiet expensive, even much more than
the Yaesu uTune system.
With 15 or 30, 1 Khz bandwidth segments or 15 or 30, 3Khz bandwidth
segments and it seems with relatively low insertion loss, I can see it's
performance would be much better than the uTune units, in some
circumstances.
Firstly I presume you would want two units, one for cw and one for ssb?
Secondly, being CAT controlled, I presume they will handle split
frequency operation?
Thirdly, these units seem to mostly only desirable by contest
operations. Probably essential when running multi-multi mode. These
multi-multi contest operations are most likely big radio clubs and so
would be happy to pay for such a device, regardless of the expense, as
they do for their antenna farms.
When chasing a rare dx stations who are working wide splits, it would be
my luck I did'nt have the 1Khz or 3Khz segment I need.
As for me, I have never experienced my FTdx3000 being overloaded by
strong in-band signals at my QTH in Australia, (not even with my
previous FT950) and I don't have any nearby broadcast stations, so is it
reasonable to say, I would not benefit from such a device or the Yaesu
uTune system?
73's, from Ron. vk3io.
On 23/12/2016 6:16 PM, Mirosław Paczocha wrote:
Hi,
In my opinion, a high selectivity device at the front end will help
regarding noise and QRM only in case of relatively poor IM3 receiver.
73, Mirek
SP5ENA
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Matt
Murphy
Sent: Thursday, December 22, 2016 11:19 PM
To: k1fz@myfairpoint.net
Cc: Topband <topband@contesting.com>
Subject: Re: Topband: "Thinking out loud"
This appears to be the 4O3A unit. I hadn't realized these existed, so I'm
glad you posted the question:
http://www.4o3a.com/index.php/products/ham-radio-gear/crystal-front-end-unit
/
On Thu, Dec 22, 2016 at 3:47 PM, K1FZ-Bruce <k1fz@myfairpoint.net> wrote:
Thanks Mirko,
Very Good information. What is needed is to reduce noise more (lower)
than signals.
73
Bruce-k1fz
On Thu, 22 Dec 2016 22:36:30 +0100, S57AD wrote:
As far as I recall, Inrad sells front-end xtal filters. Some 25
years ago when I lived in Belgrade, at YU1EXY we had two six-pole
filters for SSB part of 40M band but I can't recall and difference
with or without those filters. Beside those two xtal filters we used 8
pole Cohn LC filter with 4-gang variable capacitor and with very step
curve (I think it was 600 or
800 Hz at -6 dB), which drastically reduced noise and QRM. We could
hear 3rd or even 4th layer of callers in 40m pile-ups.
As for xtal front end filters, I think 4O3A produces such a filters to
be used at in-band stations, but didn't have chance to try & use them...
73, Mirko, S57AD
2016-12-22 21:57 GMT+01:00 K1FZ-Bruce :
Tim,
My single crystal was in the 1950's.
A crystal lattice could take in much of the 160 meter band and be
pratical.
Thanks for your input.
73
Bruce
On Thu, 22 Dec 2016 15:49:12 -0500, Tim Shoppa wrote:
Bruce - It has long been rumored that the big EU multi-multis have a
crystal filter at their run frequency receivers. e.g. if they are
running
on 7003.4, they have a crystal filter in front of their receiver for
7003.4. have never observed that in my visits but maybe in decades
past, when receivers had less damage range, it would've made sense.
Also a good reason to put up a fight for ownership of YOUR run
frequency HI HI
I believe EMRFD has a schematic for a single-frequency receiver,
maybe not exactly like you described but similar in principle. Let
me see if I can dig it up.
Tim N3QE
On Thu, Dec 22, 2016 at 3:41 PM, K1FZ-Bruce wrote:
We know that limiting the noise pick up from more directions of an
antenna
we can usually hear better. We also know if we limit the noise from
a receiver IF we can hear less noise, and better yet, if we have a
roofing filter earlier in the receiver we can eliminate even more
noise in relationship to the wanted signals.
What if we take it a step further, could we limit the band-with of
the antenna signal with a crystal lattice for 160 meters before the
receiver.
Years ago I played around with a single crystal at the input of an
old tube type receiver. It was remarkable what I could hear on 40
meters, on what seemed to be one frequency.
73
Bruce-k1fz
http://www.qsl.net/k1fz/beverage_antenna.html
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