Topband: "Thinking out loud"

Fri Dec 23 04:12:53 EST 2016

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 at contesting.com] On Behalf Of Matt
> Murphy
> Sent: Thursday, December 22, 2016 11:19 PM
> To: k1fz at myfairpoint.net
> Cc: Topband <topband at 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 at 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
>