What determines the bandwidth you hear at the loudspeaker? It's not your
roofing filter, despite a continuing notion that it is.
Dave Hachadorian's point in a post a few weeks ago was that you don't need a
1.8 kHz filter to get a 1.8 kHz bandwidth. You're free to set whatever
bandwidth you wan
I completely agree with all of that except for the very last sentence.
Clearly you've never used a 756Pro (first version) in a major CW
contest. I can remember very loud stations 10 or 15 KHz away completely
desensing my receiver to the point that the station I was trying to copy
simply dis
I too think roofing filters are really not well understood. For the
record, I have the stock SSB [2.7 KHz? I don't actually know] and the
500 Hz CW. In 99% of my operating situations, it doesn't matter which
one I use, I set the received BW with the DSP, and I'm a very happy ham.
I do have s
I can remember very loud stations 10 or 15 KHz away completely
desensing my receiver to the point that the station I was trying to
copy simply disappeared. When I switched to the K3 the difference
was astounding.
That is because the 756Pro is a completely brain dead design ... there
is only a
I would take issue with your answer to #1. It really depends on your situation.
For most of the folks on this list your answer very well may be correct. In
areas where there is very high station density, it probably is not. Here in
Silicon Valley there are a LOT of very strong near-by signals. T
ORIGINAL MESSAGE: (may be snipped)
On 5/11/2014 7:25 PM, Fred Jensen wrote:
I too think roofing filters are really not well understood.
REPLY:
A large part of the misunderstanding is due to the name. Whoever chose
the name "roofing" did a great disservice. A better name would simply
On Sun, 2014-05-11 at 22:06 -0700, Bill Turner wrote:
"I have always thought that "roofing" was a marketing ploy to imbue it
with some kind of magical powers."
Bill,
"These aren't the filters you are looking for... Move along..."
Sorry, I just had too inject that at this point in the discussio
Good point. A true roofing filter would be in the antenna line.
Repeaters have "roofing" filters, typically in the form of an extremely high
Q resonant cavity.
Chas
- Original Message -
From: "David Cole"
To:
Sent: Monday, May 12, 2014 8:43 AM
Subject: Re: [El
Well,
You defenitely need those filters in the K3.
When signals are strong and the band is busy, signals coming through the
roofing filter (line S9+20dB) is said to pump the hardware AGC, even if
you have the DSP filtering set to a small BW. Anyway, you can certainly
hear that.
Try it on CW,
net
Subject: Re: [Elecraft] [K3] Roofing filters are misunderstood
ORIGINAL MESSAGE: (may be snipped)
On 5/11/2014 7:25 PM, Fred Jensen wrote:
> I too think roofing filters are really not well understood.
REPLY:
A large part of the misunderstanding is due to the name. Whoever chose
has become corrupted over the years.
> 73 Jerry KM3K
>
>
> -Original Message-
> From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Bill
> Turner
> Sent: Monday, May 12, 2014 1:07 AM
> To: elecraft@mailman.qth.net
> Subject: Re: [Elecraft] [K3] R
sage-
> > From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of
> Bill
> > Turner
> > Sent: Monday, May 12, 2014 1:07 AM
> > To: elecraft@mailman.qth.net
> > Subject: Re: [Elecraft] [K3] Roofing filters are misunderstood
> >
> > ORI
Jerry,
Yes, the term has become corrupted and misunderstood over the years.
That *is* exactly what the K3 filters do (protect the downstream
circuits from strong out of passband signals), but is done using a much
more narrow bandwidth at the 1st IF.
If the operator never encounters signal le
Thank-you, Greg.
Excellent.
Jerry KM3K
_
From: Greg [mailto:a...@cablespeed.com]
Sent: Monday, May 12, 2014 12:52 PM
To: Jack Brindle
Cc: Jerome Sodus; elecraft@mailman.qth.net
Subject: Re: [Elecraft] [K3] Roofing filters are misunderstood
http://www.elecraft.com/K3
>
> *From:* Greg [mailto:a...@cablespeed.com]
> *Sent:* Monday, May 12, 2014 12:52 PM
> *To:* Jack Brindle
> *Cc:* Jerome Sodus; elecraft@mailman.qth.net
>
> *Subject:* Re: [Elecraft] [K3] Roofing filters are misunderstood
>
>
>
> http://www.elecraft.com/K3/Ro
I have two big time dxers/contesters near me - on 160 , one is -8 to -9 dBm
and the other is -10 to -11dBm . Folks , thats in the 50 to 100 mv area at
the poor K3 .(S9+60 to 70 area) Just for fun of it , I can easily see both
on my scope hung on my antenna.
With the 250 hz 8 pole - I could
ORIGINAL MESSAGE: (may be snipped)
On 5/12/2014 9:33 AM, Jerome Sodus wrote:
Hello Bill,
The term "roofing-filter" made sense back in the 1980's when I designed
roofing-filters at 70 MHz.
Bandwidths would be in tens of KHz.
The purpose then was to protect downstream circuitry by rejecti
At least I do, Arie. Maybe those with fewer
"local" signals do not. Dunno.
Phil w7ox
On 5/12/14, 9:23 AM, Arie Kleingeld PA3A wrote:
Well,
You defenitely need those filters in the K3.
When signals are strong and the band is busy,
signals coming through the roofing filter (line
S9+20dB) is
From an older Inrad writeup (and consistent with Wayne's):
"The term “roofing” stems from the fact that it protects the rest of the
radio following it from out of the passband signals."
http://www.qth.com/inrad/roofing-filters.pdf
I like the term "preselector" from my 75S-1, but that doesn't
I have imperfect recollections that the source of the term "roofing
filter" came from the idea that the filter put a "roof" over your
receiver to prevent very strong, off-frequency signals from getting in.
You'll need to crank up your imagination here ... similar to the roof
of your house keep
Bill,
Originally the superhet receivers converted from the signal frequency to
a lower fixed intermediate frequency in order to obtain sufficient
selectivity. IFs went as low as 85kHz until crystal filters became more
widespread. As designs changed ( changed not improved) it became usual
to
Bill,
Like a roof protects the contents of a building, a roofing filter
protects the electronics that follow it from overload.
73,
Don W3FPR
On 5/12/2014 3:01 PM, Bill Turner wrote:
I still don't get it. What does the word "roof" have to do with
bandpass? That's where the confusion comes
There you go!
Well said.
73 Jerry KM3K KX3#6088
Sent from my NOOK
Don Wilhelm wrote:
Bill,
Like a roof protects the contents of a building, a roofing filter
protects the electronics that follow it from overload.
73,
Don W3FPR
On 5/12/2014 3:01 PM, Bill Turner wrote:
>
>
> I still don't get
Roof->upper ... higher ... overhead ... protective ...
There are several fairly intuitive possibilities, none of which are
worth getting confused about in the first place.
Dave AB7E
On 5/12/2014 12:01 PM, Bill Turner wrote:
I still don't get it. What does the word "roof" have
ORIGINAL MESSAGE: (may be snipped)
On 5/12/2014 12:38 PM, Josh Fiden wrote:
"The term “roofing” stems from the fact that it protects the rest of
the radio following it from out of the passband signals."
REPLY:
A roof keeps what falls on it (rain, snow) out. It doesn't pass it
throug
Wasn't the chicken little sky is falling thing popular back when "roofing
filter" originated? We may be luckier than we know that it became known as a
roofing filter.
73 de Dennis KD7CAC
Scottsdale, AZ
On May 12, 2014, at 3:04 PM, David Gilbert wrote:
>
> Roof->upper ... higher ... o
Think of your roof blocking the rain so the ceiling doesn't have to work so
hard.
It's not used for band-pass, it's to let the DSP work less.
Sent from my iPhone
...nr4c. bill
> On May 12, 2014, at 3:01 PM, Bill Turner wrote:
>
> ORIGINAL MESSAGE: (may be snipped)
>
>> On 5/12/20
Actually, a roofing filter does exactly what it says. It protects
against ... i.e., does not allow to pass ... out-of-passband signals
from affecting the ADC or hardware AGC. It's a "roof" against unwanted
energy and a window for desired signals. So would you prefer to call it
a "window?
ORIGINAL MESSAGE: (may be snipped)
On 5/12/2014 4:15 PM, David Gilbert wrote:
So would you prefer to call it a "window?"
REPLY:
I like that! Much more accurate. A roof keeps everything out while a
window lets only certain things such as the desired signal in.
Much more self-expla
On Mon, May 12, 2014 at 8:47 PM, Bill Turner wrote:
> I like that! Much more accurate. A roof keeps everything out while a
> window lets only certain things such as the desired signal in.
>
> Much more self-explanatory.
>
Should rename them to skylight filters.. :) Holes in the roof to let stu
That's a good name.
I like it.
73 Jerry KM3K
Sent from my NOOK
Frank Precissi wrote:
On Mon, May 12, 2014 at 8:47 PM, Bill Turner wrote:
> I like that! Much more accurate. A roof keeps everything out while a
> window lets only certain things such as the desired signal in.
>
> Much more self
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