Six meter birdies.

[n7ws]

I'm still playing with my new K3 and finally got around to listening on 6-meters.  There are so many birdies as to make it unusable.

At first I thought they might be external, and some were generated in my Lenovo laptop, but shutting it down and terminating the K3 antenna port with a load doesn't eliminate them.

When listening to the same frequencies with an Icom IC-R10 with a whip antenna next to the K3 I don't hear a thing.

Ideas?

Wes  N7WS


     
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[KD7PY]

I replaced my Orion 2 + Elecraft XV50 xverter with the K3, and I find I  DO NOT  have any extra birdies that the Orion combo & a Icom IC751A + Microwave modules xverter had...& also on a Pro3
don't know if you are new to 6 meters but in the city there are a few between 50.115 - 50.120 and a couple lower in the band..
you might post the freq of the birdies you have and i'll check with my K3

Ed K7WIA

[Ken Kopp-3]

FWIW, my K3 (S/N 56) with a PR6 preamp has no 6M
birdies of any significance either ...

73! Ken Kopp - K0PP
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[Julian, G4ILO]

Ken Kopp-3 wrote

FWIW, my K3 (S/N 56) with a PR6 preamp has no 6M
birdies of any significance either ...

I think you have all missed the point that he can't hear the birdies on another receiver, and he can hear them on his K3 with only a dummy load.

Perhaps the screening panel is not grounded to the case as well as it should be?

[Enno, PF5X]

Hi Wes,

Make sure the little TMP coax cables are plugged in correctly and COMPLETELY. Also, if you have a KRX3 make sure to follow the manual wrt routing the TMP cables. I have only one birdie on 6 (~50.045) related to the KRX3/TMP cables.

-- Enno, PF5X

Wes Stewart wrote

I'm still playing with my new K3 and finally got around to listening on 6-meters.  There are so many birdies as to make it unusable.

At first I thought they might be external, and some were generated in my Lenovo laptop, but shutting it down and terminating the K3 antenna port with a load doesn't eliminate them.

When listening to the same frequencies with an Icom IC-R10 with a whip antenna next to the K3 I don't hear a thing.

Ideas?

Wes  N7WS


     
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[Matt Zilmer]

testing
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[Geoffrey Mackenzie-Kennedy]

Wes Stewart N7WS wrote:

> I'm still playing with my new K3 and finally got around to listening on
> 6-meters.  There are so many birdies as to make it unusable.
>
> At first I thought they might be external, and some were generated in my
> Lenovo laptop, but shutting it down and terminating the K3 antenna port
> with a load doesn't eliminate them.
>
> When listening to the same frequencies with an Icom IC-R10 with a whip
> antenna next to the K3 I don't hear a thing.
>
> Ideas?
>
> Wes  N7WS

----------------------------------------------------------

Wes,

>From what you have said these birdies are being generated inside the K3, if
I am right to assume that only the power supply and nothing else except the
dummy antenna load is connected to your K3, and that turning your Icom
IC-R10 on or off makes no difference to any birdies' level or frequency.

I do wonder if you have a fault in your K3 when you say 'so many birdies', I
get the impression that something is unstable on 6m but perhaps not on the
lower frequency bands. There might be a poor solder connection to a bypass
capacitor for example, which could result in problems on 6m but not on the
lower frequency bands certainly if two or more capacitors are used in
parallel,or some SMD capacitor has failed due to mechanical stress. It might
be worthwhile to troubleshoot.

Some of these internal birdies that you are hearing are probably legitimate
members of the birdie family created by the receiver's spurious response(s)
hearing one or more of the receiver's oscillators, or their products. The
frequency of these birdies can be predicted and their level can vary greatly
between identical receivers, also the routing of internal cables can become
"fussy" if shielding is inadequate or RF grounds 'float'. However this
latter issue is best left to the designer.

73,
Geoff
GM4ESD







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[oe9fwv]

hi all,

I am also suffering from birdies especially (but not only) on 6m.
I have them on the main receiver and on the subreceiver, but on different
frequencies. (found them on 40m and 20m too)
Many of them are low volume and don't bother me in real life, but some are
really loud (up to S6) and show a microfonic effect when I tap on the cover
of the K3. On the loudest one I can also hear a ticking sound when I turn the
VFO back and forth over the birdie reagion. The intensity can be tuned with
touching or taping on the synthesizer board and sometimes touching the
koax cables makes a difference.

Two friends of me with K3's also have similar birdies, one worse, one less.
One K3 from another ham friend does not show them.

Of course all my coax cables are connected, the shield of the cables is ok
and all screws of the K3 housing are tight. Different routing of the coax
cables does not help, and btw, with the limited space after adding the KRX3
there are not so many possibilities left to route the cables.

On 7 Jan 2009 at 13:01, Geoffrey Mackenzie-Kennedy wrote:

> Wes Stewart N7WS wrote:
>
> > I'm still playing with my new K3 and finally got around to listening
> > on 6-meters.  There are so many birdies as to make it unusable.
> >
> > At first I thought they might be external, and some were generated
> > in my Lenovo laptop, but shutting it down and terminating the K3
> > antenna port with a load doesn't eliminate them.
> >
> > When listening to the same frequencies with an Icom IC-R10 with a
> > whip antenna next to the K3 I don't hear a thing.
> >
> > Ideas?
> >
> > Wes  N7WS
>
> ----------------------------------------------------------
>
> Wes,
>
> >>From what you have said these birdies are being generated inside the
> >>K3, if
> I am right to assume that only the power supply and nothing else
> except the dummy antenna load is connected to your K3, and that
> turning your Icom IC-R10 on or off makes no difference to any birdies'
> level or frequency.
>
> I do wonder if you have a fault in your K3 when you say 'so many
> birdies', I get the impression that something is unstable on 6m but
> perhaps not on the lower frequency bands. There might be a poor solder
> connection to a bypass capacitor for example, which could result in
> problems on 6m but not on the lower frequency bands certainly if two
> or more capacitors are used in parallel,or some SMD capacitor has
> failed due to mechanical stress. It might be worthwhile to
> troubleshoot.
>
> Some of these internal birdies that you are hearing are probably
> legitimate members of the birdie family created by the receiver's
> spurious response(s) hearing one or more of the receiver's
> oscillators, or their products. The frequency of these birdies can be
> predicted and their level can vary greatly between identical
> receivers, also the routing of internal cables can become "fussy" if
> shielding is inadequate or RF grounds 'float'. However this latter
> issue is best left to the designer.
>
> 73,
> Geoff
> GM4ESD
>
>
>
>
>
>
>
>
>

--  
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MasterCard.



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[wayne burdick]

Some birdies are unavoidable in a high-dynamic-range, down-conversion
design. We worked very hard to keep them out of the ham bands, and in
the case of 6 m, we focused on keeping them out of the portion of the
band typically used for weak-signal work. (The Orion has a similar
conversion scheme to the K3's, but doesn't provide 6 meter coverage.
That simplifies things  ;)

Up-conversion transceivers generally have fewer spurious signals on 6
m, but they also typically have very weak receivers, due to the use of
wide first I.F. filters, as well as very high-frequency 1st LOs with
much worse minimum phase noise than the K3.

Birdies usually result from VHF or UHF harmonics of the K3's high-level
signal sources, mixed with another signal source, internal or external.
In both cases, they may not actually be on the band you think they are;
they could be on an image band, circumventing the filters. External VHF
or UHF signals could be getting in through other I/O besides the
antenna jack, and every receiver will respond differently to them.

So, while a given VHF receiver with a whip doesn't pick them up, that
doesn't mean they aren't there--they could just be well outside the 6-m
band, and mixing to produce a response in the K3. The only way to tell
for sure is to put the unit under test in a screen room.

It's possible to eliminate every last portal for such signals, but to
do so would take many pound's worth (and $ worth) of additional
shielding, bypassing, and filtered connectors. That's just not possible
within the K3's budget or package size, so we aimed for the best
possible compromise.

All that said, there are things we can do on an individual K3:

1. Make sure that the screw from the left side panel into the front
shield is tight. If a birdie drops a lot in amplitude when you wedge a
knife blade between these two panels, near the screw, then the panels
aren't making good electrical contact. We're considering whether to add
a small piece of copper EMI tape here so that the screw tension isn't
so critical.

2. EMI tape can be applied in various places within the cabinet,
typically along seams where panels join. This tape is very expensive.
Some experimentation may be in order here to see were we can get the
most bang for the buck (dB for the inch?).

3. Specific birdies due to VHF harmonics can sometimes be shifted out
of harm's way just by shifting the passband (SHIFT control) or
selecting a different crystal filter. The reason for this is that it
moves the synthesizer (1st LO).

4. If all else fails, try turning on the notch filter. You can use
auto-notch in voice modes, but in CW mode you're limited to manual
notch.

If you still feel that your K3 has excessive 6-m birdies, or that
they're causing specific operating problems, please contact me directly
and I'll try to help work out a solution.

73,
Wayne
N6KR


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[giuliano-8]

I had some birds using a switching Power supply.I have no birds, with a
linear Power supply.
 I have also noted some birds if cover has removed.
73
Giuliano I0CG
K3 # 1814

-----Dr. Werner Furlan wrote:-----------------------


hi all,

I am also suffering from birdies especially (but not only) on 6m.
I have them on the main receiver and on the subreceiver, but on different
frequencies. (found them on 40m and 20m too)
Many of them are low volume and don't bother me in real life, but some are
really loud (up to S6) and show a microfonic effect when I tap on the cover
of the K3. On the loudest one I can also hear a ticking sound when I turn the
VFO back and forth over the birdie reagion. The intensity can be tuned with
touching or taping on the synthesizer board and sometimes touching the
koax cables makes a difference.

Two friends of me with K3's also have similar birdies, one worse, one less.
One K3 from another ham friend does not show them.

Of course all my coax cables are connected, the shield of the cables is ok
and all screws of the K3 housing are tight. Different routing of the coax
cables does not help, and btw, with the limited space after adding the KRX3
there are not so many possibilities left to route the cables.


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[wayne burdick]

wayne burdick wrote:

> 3. Specific birdies due to VHF harmonics can sometimes be shifted out
> of harm's way just by shifting the passband (SHIFT control) or
> selecting a different crystal filter. The reason for this is that it
> moves the synthesizer (1st LO).

I forgot to mention that in CW mode, a birdie due to high VHF/UHF
signal mixing can often be moved or eliminated altogether by switching
to CW REV (CW reverse, i.e. opposite-sideband-CW). The K3 works just as
well either way, but CW REV moves the LOs and thus may move the birdie.

73,
Wayne
N6KR

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