Re: Topband: Front End Filters

[Raoul Coetzee via Topband]

surely it is important to have the correct loading on the crystal,  just 
connecting a crystal in the antenna path is not so good?It seems good loading 
is around 1-3k.
Merry Christmas to all.Raoul ZS1C 



  From: K1FZ-Bruce 
 To: topband@contesting.com; Dave  
 Sent: Saturday, December 24, 2016 7:48 AM
 Subject: Topband: Front End Filters
   
 
The one they are  developing for marketing 'can' have 1 KHZ segment 
crystals channels.. 
 
I would encourage anyone to insert a single crystal in their receiver 
antenna input to see the
difference before considering a purchase.  (Careful not to transmit 
into the experiement)
40 meters is a good test  band as usually has many signals after dark.. 
 
73
Bruce-k1fz
 
 

On Fri, 23 Dec 2016 17:56:07 -0700, Dave  wrote:

      About 15 years ago I built a switchable front end crystal filter, I was
going to market it but it was too expensive for the Ham market. It covers
1800 to 1850 in 5kHz segments with a slight overlap so that there are no
gaps, each section is a half lattice, the insertion loss is about 6dB but
that isn't a problem because I always have about -15dB of attenuation in the
receive path input. Nose bandwidth is 5kHz and about 8kHz at -20dB. Lack of
noise blanker performance is not a problem because big signals make the
blanker useless anyway. I used it during contests when my rig was an IC781,
since changing to a more modern rig, an IC7851, the filter provides no
significant improvement. For working DX on a crowded band it is useful if
your rig does not have a good roofing filter. 

HNY /MX

Dave AA0RS

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Topband: Front End Filters

[K1FZ-Bruce]

 
The one they are  developing for marketing 'can' have 1 KHZ segment 
crystals channels.. 
 
I would encourage anyone to insert a single crystal in their receiver 
antenna input to see the
difference before considering a purchase.  (Careful not to transmit 
into the experiement)
40 meters is a good test  band as usually has many signals after dark.. 
 

73
Bruce-k1fz
 
 

On Fri, 23 Dec 2016 17:56:07 -0700, Dave  wrote:

  About 15 years ago I built a switchable front end crystal filter, I was
going to market it but it was too expensive for the Ham market. It covers
1800 to 1850 in 5kHz segments with a slight overlap so that there are no
gaps, each section is a half lattice, the insertion loss is about 6dB but
that isn't a problem because I always have about -15dB of attenuation in the
receive path input. Nose bandwidth is 5kHz and about 8kHz at -20dB. Lack of
noise blanker performance is not a problem because big signals make the
blanker useless anyway. I used it during contests when my rig was an IC781,
since changing to a more modern rig, an IC7851, the filter provides no
significant improvement. For working DX on a crowded band it is useful if
your rig does not have a good roofing filter. 


HNY /MX

Dave AA0RS

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Re: Topband: (no subject)

[JC]

DON’T OPEN THE LINK IT NOT FROM ME. IT MAY BE  A VIRUS!

 

 

From: 'topband' [mailto:topband@contesting.com] 
Sent: Friday, December 23, 2016 8:33 PM
To: n...@comcast.net
Subject: 

 

"Re: Topband: Radio World; Noise Floor; Where do we go from here?" 

JC doc 

  

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Topband: Front End Filters

[Dave]

About 15 years ago I built a switchable front end crystal filter, I was
going to market it but it was too expensive for the Ham market. It covers
1800 to 1850 in 5kHz segments with a slight overlap so that there are no
gaps, each section is a half lattice, the insertion loss is about 6dB but
that isn't a problem because I always have about -15dB of attenuation in the
receive path input. Nose bandwidth is 5kHz and about 8kHz at -20dB.  Lack of
noise blanker performance is not a problem because big signals make the
blanker useless anyway. I used it during contests when my rig was an IC781,
since changing to a more modern rig, an IC7851, the filter provides no
significant improvement. For working DX on a crowded band it is useful if
your rig does not have a good roofing filter.

 

HNY /MX

 

Dave AA0RS

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Topband: "Thinking out loud" - Something else to Think About (REV)

[Dave Bowker via Topband]

Crystal filters are nonlinear passive devices by nature of the characteristics 
of the crystal(s).  The motional characteristic of a quartz crystal is a 
function of the level of the signal applied to it, known as drive level 
dependence or (DLD) in engineering terms.  Crystal filters can contribute 
inter-modulation when a strong out-of-pass-band signal is present, whether the 
undesired signal is immediately adjacent to the pass band frequency or removed 
some distance in frequency from it.

Another concern of placing a narrow bandwidth filter in the RX input is the 
effect it has upon the receiver impulse noise blanker.  A narrow bandwidth 
filter stretches the noise pulse bandwidth by many orders of magnitude and can 
render the NB ineffective and contributes IMD products.  For this reason, in 
modern day receivers, the noise blanker sampling/processing is placed ahead of 
the narrow band IF filters.  

Placing a narrow bandwidth filter at the input of the RX will cause IMD if the 
NB is in use.

In a contest operation the input filter will be subjected to MULTIPLE nearby 
strong signals that are not in the pass band of the filter.  This condition is 
accentuated in a multi-multi operation.

Dave, K1FK
Fort Kent, ME
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Topband: "Thinking out loud" - Something else to Think About

[Dave Bowker via Topband]

Crystal filters are nonlinear passive devices by natureof the characteristics 
of the crystal(s).  The motional characteristic ofa quartz crystal is a 
function of the level of the signal applied to it, knownas drive level 
dependence or (DLD) in engineering terms.  Crystal filters can 
contributeinter-modulation when a strong out-of-pass-band signal is present, 
whether theundesired signal is immediately adjacent to the pass band frequency 
or removedsome distance in frequency from it.

Another concern of placing a narrow bandwidth filter inthe RX input is the 
effect it has upon the receiver impulse noiseblanker.  A narrow bandwidth 
filter stretches the noise pulse bandwidth bymany orders of magnitude and can 
render the NB ineffective and contributes IMDproducts.  For this reason, in 
modern day receivers, the noise blankersampling/processing is placed ahead of 
the narrow band IF filters.  

Placing a narrow bandwidth filter atthe input of the RX will cause IMD if the 
NB is in use.
In a contest operationthe input filter will be subjected to MULTIPLE nearby 
strong signals that arenot in the pass band of the filter.  This condition is 
accentuated in amulti-multi operation.
Dave, K1FKFort Kent, ME
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Re: Topband: "Thinking out loud"

[Mark Schoonover]

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  
Website: http://www.ka6wke.net


On Fri, Dec 23, 2016 at 1:12 AM, vk3io  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-boun...@contesting.com] On Behalf Of Matt
>> Murphy
>> Sent: Thursday, December 22, 2016 11:19 PM
>> To: k...@myfairpoint.net
>> Cc: Topband 
>> 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  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 

Topband: Fwd: RTTY Beacon

[Joe Galicic]

Response from Warren below. He was very strong so it was not a harmonic. He was 
there on purpose. Not sure if we have experimental frequencies below 160 meters 
? 

- Original Message -


Joe, 
Thanks for the report! 
Running abt 75W into an inverted L 
73 Warren 

On 12/22/2016 4:55 AM, Joe Galicic wrote: 
> Heard WH2XDE\3 beacon 0950Z on 1790.9KHZ Very loud S9 plus. -Joe N3HEE 


--- 
This email has been checked for viruses by Avast antivirus software. 
https://www.avast.com/antivirus 


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Re: Topband: "Thinking out loud"

[vk3io]

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-boun...@contesting.com] On Behalf Of Matt
Murphy
Sent: Thursday, December 22, 2016 11:19 PM
To: k...@myfairpoint.net
Cc: Topband 
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  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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