Bad Filters

[kd1na]

Jerry,

When I got my K3 I found the FM filter was open (no signals). When Electaft Support sent me a replacement I could only get 1.5 watts out through the filter (verses 100 watts through a ,001 UF capacitor) on FM.

When I again contacted Support, I suggested that they plug the FM filter into a K3 and test it before they send it to me. When I got the replacement FM filter (My second replacement) it worked fine.

To answer your question, I don't think they test all filters.

73
Dave KD1NA
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[Eric Swartz - WA6HHQ]

We do now!

Originally all 8 pole filters were supposed to be 100% tested at INRAD's
supplier. When we discovered some bad ones had gotten through, we added
100% testing at Elecraft and at INRAD in Aptos.

73, Eric   WA6HHQ

_..._



David Robertson wrote:

> Jerry,
>
> When I got my K3 I found the FM filter was open (no signals). When Electaft Support sent me a replacement I could only get 1.5 watts out through the filter (verses 100 watts through a ,001 UF capacitor) on FM.
>
> When I again contacted Support, I suggested that they plug the FM filter into a K3 and test it before they send it to me. When I got the replacement FM filter (My second replacement) it worked fine.
>
> To answer your question, I don't think they test all filters.
>
> 73
> Dave KD1NA
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[Arie Kleingeld PA3A]

That Elecraft is testing the filters now is a good thing!

I remember a post from Elecraft a few months ago, that said that I
should not use the 8.2M IF filters that were intended for Yaesu's FT1K
because the filters for the Elecraft K3 were specially selected to get
top performance.

The recent messages of bad filters, 8-pole and 5-pole, seem to
contradict that. Or do filters break down during transport?

Anyway, awaiting my new K3 with several filters within a few weeks from
now, I expect that my filters are thouroughly tested for flatness, good
imd-performance and are handpicked for top performance.... As promised.

Or is this an impossible, strange question? Then please say so.


73
Arie PA3A
K2 36..something


(BTW, I've  got four 8.2M IF filters in my FT1K)






-----Oorspronkelijk bericht-----
Van: [hidden email]
[mailto:[hidden email]] Namens Eric Swartz WA6HHQ -
Elecraft
Verzonden: zaterdag 21 juni 2008 5:00
Aan: David Robertson
CC: Elecraft
Onderwerp: Re: [Elecraft] Bad Filters


We do now!

Originally all 8 pole filters were supposed to be 100% tested at INRAD's

supplier. When we discovered some bad ones had gotten through, we added
100% testing at Elecraft and at INRAD in Aptos.

73, Eric   WA6HHQ

_..._


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[David Cutter]

I find it difficult to believe that a filter will go bad between
manufacturer and customer.  Perhaps the odd one in 1000 might get past the
manufacturer's test regime.  Modern surface mount components and hybrids are
very sturdy and no postal service could impart sufficient vibration or shock
to these devices to cause damage, particularly as these are soft-packed to
absorb shocks.  It's even more improbable that it could change the
performance by just a few dB that all but the best test equipment could
reveal.

I am not able to test that the filters I purchased are up to spec, but if
there have been significant numbers of failures (and the extraordinary
failure of one in a reviewer's sample), I'm coming to the conclusion that
filters should be returned to be re-tested, since the recent history
indicates a faulty test and / or manufacturing regime.

INRAD is a well-respected manufacturer, so, for Elecraft to re-test their
work (with all the calibration problems that engages) is a plus for our
confidence in the final product but a distinct fear that those filters
produced prior to this time are statistically more likely to have failures
amongst them.

Eric, is this something Elecraft could offer?

David
G3UNA

> That Elecraft is testing the filters now is a good thing!
>
> I remember a post from Elecraft a few months ago, that said that I
> should not use the 8.2M IF filters that were intended for Yaesu's FT1K
> because the filters for the Elecraft K3 were specially selected to get
> top performance.
>
> The recent messages of bad filters, 8-pole and 5-pole, seem to
> contradict that. Or do filters break down during transport?
>
> Anyway, awaiting my new K3 with several filters within a few weeks from
> now, I expect that my filters are thouroughly tested for flatness, good
> imd-performance and are handpicked for top performance.... As promised.
>
> Or is this an impossible, strange question? Then please say so.
>
>
> 73
> Arie PA3A
> K2 36..something
> >
>
> We do now!
>
> Originally all 8 pole filters were supposed to be 100% tested at INRAD's
>
> supplier. When we discovered some bad ones had gotten through, we added
> 100% testing at Elecraft and at INRAD in Aptos.
>
> 73, Eric   WA6HHQ
>

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[Julian, G4ILO]

David Cutter wrote

I am not able to test that the filters I purchased are up to spec, but if
there have been significant numbers of failures (and the extraordinary
failure of one in a reviewer's sample), I'm coming to the conclusion that
filters should be returned to be re-tested, since the recent history
indicates a faulty test and / or manufacturing regime.

INRAD is a well-respected manufacturer, so, for Elecraft to re-test their
work (with all the calibration problems that engages) is a plus for our
confidence in the final product but a distinct fear that those filters
produced prior to this time are statistically more likely to have failures
amongst them.

Eric, is this something Elecraft could offer?

David
G3UNA

If nothing is obviously wrong with the radio, I can't see the point of returning filters to Elecraft for testing, especially all the way from the UK (and at whose expense?) and being without a working radio for a couple of weeks, in all likelihood to prove that nothing is wrong with them.

Normal component variations will account for slight differences in the performance of individual radios in any case. Some of us will have a radio that is at the low end of certain specification ranges, and others will have one at the high end. Some may have a slightly better performing receiver but a slightly worse performing transmitter, or vice versa. But I very much doubt if you could tell the difference between them if they were side by side, without the aid of a lab full of test equipment. These test results just encourage people to obsess over differences in performance that probably can not be discerned in actual on-air operation.

As far as I am concerned, if my K3 seems OK to me then it *is* OK.

[David Cutter]

Well, the radio seems ok, but there will be occasions, such as operating
near to very strong in-band signals when it may perform less than
satisfactorily and it is hard to identify what is happening.  There may well
be artefacts that are disturbing and only heard on odd occasions such as
this and reduce the effectiveness of the radio in a contest for instance,
and it is difficult to reproduce those conditions on the bench, ie multiple
very strong signals near a weak one.  I know someone who receives 55-60dB
over 9 bc signals on 40m and the K3 probably cannot cope with this.

I think the point about making standardised measurements is that they are
standard, but most of the time you wouldn't notice if you were compliant or
not.  In days of old when assessing military radios returned for service, it
was established that >60% failed the spec and were not reported by the
operator for those failures.  So, I think I would like to know that my radio
is compliant with its spec then I can look elsewhere when a problem occurs.

David
G3UNA>>

>
> If nothing is obviously wrong with the radio, I can't see the point of
> returning filters to Elecraft for testing, especially all the way from the
> UK (and at whose expense?) and being without a working radio for a couple
> of
> weeks, in all likelihood to prove that nothing is wrong with them.
>
> Normal component variations will account for slight differences in the
> performance of individual radios in any case. Some of us will have a radio
> that is at the low end of certain specification ranges, and others will
> have
> one at the high end. Some may have a slightly better performing receiver
> but
> a slightly worse performing transmitter, or vice versa. But I very much
> doubt if you could tell the difference between them if they were side by
> side, without the aid of a lab full of test equipment. These test results
> just encourage people to obsess over differences in performance that
> probably can not be discerned in actual on-air operation.
>
> As far as I am concerned, if my K3 seems OK to me then it *is* OK.
>
> -----
> Julian, G4ILO  K3 s/n: 222 K2 s/n: 392

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[Geoffrey Mackenzie-Kennedy]

While I agree with you David and Julian's point about shipping costs etc,  I
would suggest that in this case the fundamental questions are whether or not
the filter's specification does include IIP3 minimum limits and what are
they. Because, and understandably so, the dynamic range data published by
the RSGB, ARRL and others reflects the preformance of the receiver as a
whole and not of its filters as stand alone components, I have asked INRAD
whether or not they do include IIP3 in their filter specifications or test
for IIP3 as part of their QC.

Multiple signal dynamic range testing is commonly practiced by some when
developing high performance receivers, and can better unearth the sort of
IMD problems that often arise during a contest or during a 'no-split' pile
up than two signal tests. Many filters fall apart in terms of generated IMD
when subjected to multiple signal tests, and I suspect that many people (I
certainly used to!) think that the IMD products are real signals causing
QRM. The problem gets significantly worse of course if the IF cascade's
dynamic range is 'poor'.

There is no doubt in my mind that if a receiver is expected to dig out weak
signals among close spaced 60-65 db over S9 BC stations, every last db of
close in dynamic range does help.  BC transmitter phase noise is not the
problem that one might expect it to be.

73,
Geoff
GM4ESD


David Cutter wrote on Saturday, June 21, 2008 11:05 AM

> Well, the radio seems ok, but there will be occasions, such as operating
> near to very strong in-band signals when it may perform less than
> satisfactorily and it is hard to identify what is happening.  There may
> well be artefacts that are disturbing and only heard on odd occasions such
> as this and reduce the effectiveness of the radio in a contest for
> instance, and it is difficult to reproduce those conditions on the bench,
> ie multiple very strong signals near a weak one.  I know someone who
> receives 55-60dB over 9 bc signals on 40m and the K3 probably cannot cope
> with this.
>
> I think the point about making standardised measurements is that they are
> standard, but most of the time you wouldn't notice if you were compliant
> or not.  In days of old when assessing military radios returned for
> service, it was established that >60% failed the spec and were not
> reported by the operator for those failures.  So, I think I would like to
> know that my radio is compliant with its spec then I can look elsewhere
> when a problem occurs.
>
> David
> G3UNA

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