I've spent some time using the MFJ-1026 noise canceler. It took some effort
to get it to work, I had to come up with a much better noise antenna. I
bought one of those 8' crappie poles from local big chain and spiral
wrapped about 50' of wire on it. I mounted it in the clear as close to my
neighbors houses. It takes some practice to null noise out but it's really
worth the effort. I'm on the west coast outside of San Diego and during
2015 WPX CW contest, I worked D4C on 160. Granted that station is in the
elite status but my IC-7410 with 100 watts into a 36' vertical and a 40M
loop as a caphat, I was able to log the contact. I'm on a small lot with
the longest dimension about 80'. I've been able to put down 2 ~200' radials
that go around the perimeter of my property. Definitely though, SNR is
king. I keep the AF gain at max and ride the RF gain. The sensitivity of
modern rigs is rather amazing but that also means more noise is also
received.
73! Mark KA6WKE
4NEC2 The Definitive Guide <https://leanpub.com/4nec2definitiveguide>
Website: http://www.ka6wke.net
On Fri, Dec 23, 2016 at 1:12 AM, vk3io <vk3io@iinet.net.au> wrote:
> 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/crysta
>> l-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
>>>>
>>> _________________
>>> Topband Reflector Archives - http://www.contesting.com/_topband
>>>
>>>
>>>
>>> ----- End forwarded message -----
>>>
>>> _________________
>>> Topband Reflector Archives - http://www.contesting.com/_topband
>>>
>>> _________________
>> Topband Reflector Archives - http://www.contesting.com/_topband
>>
>> _________________
>> Topband Reflector Archives - http://www.contesting.com/_topband
>>
>>
> _________________
> Topband Reflector Archives - http://www.contesting.com/_topband
>
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
|