Elecraft

8 pole vs 5 pole..I knew this would happen

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KK7P

Re: 8 pole vs 5 pole..I knew this would happen

> Given that I hardly ever, but maybe now and then operate SSB, and would
> like to try other digital modes, what would suggest as a reasonable
> approach to filters?

I'd start with the default 2.7 kHz filter. It'll handle the new, wider
digital modes like Olivia, and handle SSTV and digital voice, for
example. If you operate mostly CW or mostly narrow digital modes, I'd
add the 400 Hz or 500 Hz filter. Then operate the radio for a while and
see what else you'd like/want/need.

73,

Lyle KK7P

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Geoffrey Mackenzie-Kennedy-2

Re: 8 pole vs 5 pole..I knew this would happen

In reply to this post by N8LP

With respect Larry I must disagree about the term "roofing filter" being
misleading. I completely agree that a narrow filter at the first IF is
desireable if not essential, and it could be identified as a roofing filter
in some instances - see below. This approach has been the norm in the design
of certain classes of high performance receiver for some time, and obviously
this filter's bandwidth must be compatible with the receiver's operating
mode.

I think that the confusion in understanding the meaning of the term "roofing
filter" started in the amateur community sometime after commercial double
conversion receivers began to appear on the amateur market, and appears to
be increasing. Because these receivers used very wide roofing filters, and
many still do, the myth arose that roofing filters were always wide and were
only used in double conversion receivers. In turn this gave birth to other
myths about the poor performance of double conversion receivers vs single
conversion receivers, which often can be traced back to poor design and poor
electro-mechanical construction. The term "roofing filter" was intended, and
has since when correctly used, to identify the first narrow bandwidth IF
filter appearing in a receiver's signal path after the first signal mixer,
but *only* in those cases where additional IF filtering was introduced
further down the IF chain for the purpose of establishing the overall RF /
IF selectivity - as found in many amateur double conversion receivers and
early single conversion ISB receivers for example. In the ISB receivers with
which I was involved in the 1950s, the typical bandwidth of the roofing
filter was slightly greater than twice the required traffic bandwidth of
each of the following USB and LSB filters i.e.roughly speaking 7 kHz for a
basic two channel at baseband receiver, not tens of kHz. In later years a
variety of roofing filters, some wide some very narrow have crossed my path.
The term does *not* and was *not* intended to imply that that the receiver's
architecture is double conversion nor that the bandwidth of the roofing
filter is by default wide, and is not used to identify any filter outside of
the IF cascade. Although it is tempting to identify the roofing filter as
the 1st IF filter, this could imply that there were other IFs used elsewhere
in the receiver in question e,g dual conversion or triple conversion, and is
usually avoided.

In the case of a straightforward single conversion receiver using a single
set of filters (or variable bandwidth in the case of the K2) the IF filter
should not be identified as a roofing filter.The small filter prior to a
product detector to attenuate unwanted sideband IF generated noise does not
count as a second filter, because according to the "rules" the same result
can be achieved by using an image reject mixer as a product detector On the
other hand if for some strange reason a single conversion comms receiver did
employ a widish bandwidth IF filter close after the mixer and narrow
bandwidth IF filters further down the IF chain, at the risk of questionable
IMD performance if the cascade between the filters is weak, it would be
correct to identify the first filter as a roofing filter.

In my opinion if a filter is performing the role of a roofing filter its
identity should not be changed from "roofing filter", which is a well
established term both inside and outside of the amateur community.

73,
Geoff
GM4ESD

On Friday, May 04, 2007, at 2:11 AM, Larry Phipps wrote:

>I think the term "roofing filter" is misleading. A narrow filter at the
>first IF protects a receiver even better than a "roofing filter", so there
>is nothing inherently distortion reducing in using a wider filter at the
>first IF and then a narrower one later. The ideal situation for IMD would
>be a pair of matched narrow filters at both IFs. The real reason for a
>"roofing filter" it seems to me, is to allow passband or slope tuning. This
>compromises IMD and AGC performance for the sake of a feature... which may
>or may not be valuable to the user.
>
> Therefore, the "roofing filter" should be termed the "passband tuning
> enabling filter", or "PBTE" filter ;-)
>
> Thankfully, I think Elecraft has done a brilliant job of giving us the
> options we want without compromises. By tying the DSP bandwidths and PBT
> functions to the "roofing filters", we have the ability to have the
> combination of 1st and 2nd IF BW we want,,, and with the variable "roofing
> filters", I think we will be able to almost set the relative BWs between
> the two... allowing a window for PBT or not as we choose. This is an
> exciting development, and will be copied by many companies over the next
> year. Kudos to the design team on this.
>
> 73,
> Larry N8LP

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Eric Swartz - WA6HHQ

Re: So, How Many K3 Orders?

Administrator

In reply to this post by Paul Clay-2

Hi Paul,

Absolutely! Much earlier than that. We have increased our first runs to
accommodate the order rate.

73, Eric
-------

Paul Clay wrote:

> Hi!
>
> I'm wondering; if order my K3 today (paying half down)
> will I receive it by Christmas '07? ;=) I seem to
> recall seeing the question posed, but missed seeing
> the answer; how many K3s does Elecraft expect to be
> producing/delivering each month?
>
> - Paul
>

dj7mgq

Re: So, How Many K3 Orders?

> Absolutely! Much earlier than that. We have increased our first runs to
> accommodate the order rate.

I knew it... The pre-paids are going to break the 200 (or 220 depending on which
file you read), meaning to keep the promise of serial number of under 200 (or
220), Elecraft will have to do something like this:

20
21
22
..
197
198
199aa
199ab
199ac
..
199zz
200

Like I suggested to Wayne several days ago, Elecraft could offer vanity numbers,
e.g. I wouldn't mind 199td.

Only joking... I think...

Best 73s

Toby

PS: ... Money for nothing and my rigs are three ...
--
DD5FZ, 4N6FZ
K2 #885, K2/100 #3248, K3 #<200
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N8LP

Re: 8 pole vs 5 pole..I knew this would happen

In reply to this post by KK7P

Yes, again reinforcing my point, Lyle, although you always seem to state
it better. The more I learn about this rig the more I want to play with it.

73,
Larry N8LP

Lyle Johnson wrote:

>> Yes, that is exactly the point I was trying to make! You can have it
>> as you like it (I am speculating a bit about the control options in
>> the firmware, of course). Some people like a wider width at the first
>> IF to hear signals approaching, even if it opens the window for AGC
>> blocking or desense. Others would want the two passbands to be
>> exactly aligned and as narrow as possible, which would provide the
>> best IMD and AGC performance, but then the signals will drop off the
>> cliff as you tune. What you appear to have done is allow nuance in
>> these adjustments, which I think is quite clever and well thought
>> out. I can't wait to play with it.
>
> One other feature you're sure to like, then, is the CW "context" or
> "PB2" filter. Set this one as wide as you like -the crystal filter
> selection will be driven by this. Then set a "suppression level"
> maybe down 10 or 20 or 30 dB. Overlay this with the narrow filter you
> want and presto! You can hear the context from nearby stations, but
> at reduced amplitude, while the signals in the narrow filter you are
> working (or trying to work :-) are emphasized and drive the AGC level.
>
> 73,
>
> Lyle KK7P
>
>
> .
>

N8LP

Re: 8 pole vs 5 pole..I knew this would happen

In reply to this post by Geoffrey Mackenzie-Kennedy-2

Hi Geoff. My post was somewhat tongue-in-cheek, and it's mostly
semantics, but I would say that the K3 filter would be a roofing filter
or not depending on your settings. I guess my opinion is that if it's
set for the same BW as the 2nd IF, then its not a roofing filter, and if
it's set wider then it is. At any rate, it's a roofing filter since that
what they decided to call it, and would usually be used that way. The
beauty of the design is that it doesn't have to be.

One other bit of semantics... if the DSP filter is set wider than the
roofing filter (if the firmware even allows this), then the term roofing
filter would definitely not be correct, and the DSP filter would then be
an "image reject filter" or something similar ;-)

I think I will coin another term for Elecraft... FDR, for Firmware
Defined Radio ;-)

73,
Larry N8LP

Geoffrey Mackenzie-Kennedy wrote:

> With respect Larry I must disagree about the term "roofing filter"
> being misleading. I completely agree that a narrow filter at the
> first IF is desireable if not essential, and it could be identified as
> a roofing filter in some instances - see below. This approach has been
> the norm in the design of certain classes of high performance receiver
> for some time, and obviously this filter's bandwidth must be
> compatible with the receiver's operating mode.
>
> I think that the confusion in understanding the meaning of the term
> "roofing filter" started in the amateur community sometime after
> commercial double conversion receivers began to appear on the amateur
> market, and appears to be increasing. Because these receivers used
> very wide roofing filters, and many still do, the myth arose that
> roofing filters were always wide and were only used in double
> conversion receivers. In turn this gave birth to other myths about the
> poor performance of double conversion receivers vs single conversion
> receivers, which often can be traced back to poor design and poor
> electro-mechanical construction. The term "roofing filter" was
> intended, and has since when correctly used, to identify the first
> narrow bandwidth IF filter appearing in a receiver's signal path after
> the first signal mixer, but *only* in those cases where additional IF
> filtering was introduced further down the IF chain for the purpose of
> establishing the overall RF / IF selectivity - as found in many
> amateur double conversion receivers and early single conversion ISB
> receivers for example. In the ISB receivers with which I was involved
> in the 1950s, the typical bandwidth of the roofing filter was slightly
> greater than twice the required traffic bandwidth of each of the
> following USB and LSB filters i.e.roughly speaking 7 kHz for a basic
> two channel at baseband receiver, not tens of kHz. In later years a
> variety of roofing filters, some wide some very narrow have crossed my
> path. The term does *not* and was *not* intended to imply that that
> the receiver's architecture is double conversion nor that the
> bandwidth of the roofing filter is by default wide, and is not used to
> identify any filter outside of the IF cascade. Although it is tempting
> to identify the roofing filter as the 1st IF filter, this could imply
> that there were other IFs used elsewhere in the receiver in question
> e,g dual conversion or triple conversion, and is usually avoided.
>
> In the case of a straightforward single conversion receiver using a
> single set of filters (or variable bandwidth in the case of the K2)
> the IF filter should not be identified as a roofing filter.The small
> filter prior to a product detector to attenuate unwanted sideband IF
> generated noise does not count as a second filter, because according
> to the "rules" the same result can be achieved by using an image
> reject mixer as a product detector On the other hand if for some
> strange reason a single conversion comms receiver did employ a widish
> bandwidth IF filter close after the mixer and narrow bandwidth IF
> filters further down the IF chain, at the risk of questionable IMD
> performance if the cascade between the filters is weak, it would be
> correct to identify the first filter as a roofing filter.
>
> In my opinion if a filter is performing the role of a roofing filter
> its identity should not be changed from "roofing filter", which is a
> well established term both inside and outside of the amateur community.
>
> 73,
> Geoff
> GM4ESD
>
>
> On Friday, May 04, 2007, at 2:11 AM, Larry Phipps wrote:
>
>> I think the term "roofing filter" is misleading. A narrow filter at
>> the first IF protects a receiver even better than a "roofing filter",
>> so there is nothing inherently distortion reducing in using a wider
>> filter at the first IF and then a narrower one later. The ideal
>> situation for IMD would be a pair of matched narrow filters at both
>> IFs. The real reason for a "roofing filter" it seems to me, is to
>> allow passband or slope tuning. This compromises IMD and AGC
>> performance for the sake of a feature... which may or may not be
>> valuable to the user.
>>
>> Therefore, the "roofing filter" should be termed the "passband tuning
>> enabling filter", or "PBTE" filter ;-)
>>
>> Thankfully, I think Elecraft has done a brilliant job of giving us
>> the options we want without compromises. By tying the DSP bandwidths
>> and PBT functions to the "roofing filters", we have the ability to
>> have the combination of 1st and 2nd IF BW we want,,, and with the
>> variable "roofing filters", I think we will be able to almost set the
>> relative BWs between the two... allowing a window for PBT or not as
>> we choose. This is an exciting development, and will be copied by
>> many companies over the next year. Kudos to the design team on this.
>>
>> 73,
>> Larry N8LP
>
>
>
>

N8LP

Re: So, How Many K3 Orders?

In reply to this post by Eric Swartz - WA6HHQ

I hope you guys aren't planning any time off this year! (Actually I hope
you are or you will lose your sanity). After Dayton and an ARRL product
review, you will probably have a 12 month backlog ;-)

73,
Larry N8LP

Eric Swartz - WA6HHQ, Elecraft wrote:

> Hi Paul,
>
> Absolutely! Much earlier than that. We have increased our first runs
> to accommodate the order rate.
>
> 73, Eric
> -------
>
> Paul Clay wrote:
>> Hi!
>>
>> I'm wondering; if order my K3 today (paying half down)
>> will I receive it by Christmas '07? ;=) I seem to
>> recall seeing the question posed, but missed seeing
>> the answer; how many K3s does Elecraft expect to be
>> producing/delivering each month?
>> - Paul
>>
> _______________________________________________
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> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
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>
>