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P3 RFI

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KD7PY

P3 RFI

FWIW

This morning we had a very good opening on 6 meters to the east coast Maine down to Florida from the PNW,
When the band died, I thought it would be a good time to go out and snoop the neighborhood for the line noise source that bugs me, So i got out my MFJ Line Noise Meter, put it on the desk to put in a new battery. I turned it on and what a racket. so I snooped the shack and found it comes from the P3.
turn the power off on the P3 and silence, I could get 30 feet away before I could not hear it any more.
I don't hear any of the RFI on any band 160<>6. So I don't know if it is there on 2 meters, The MFJ receives on the Aircraft band around 137 MHZ. so I don't know if would effect 2 meters or not.

Ed K7WIA

Stephen G4SJP

Re: P3 RFI

Ed,

Listening on a TH-D72 on about 137MHz, yes the noise from the P3 is indeed
loud. However, by the time I have more than a metre or so separation
between the P3 and the handie, the noise drops below the handie's squelch
threshold, so for me at least, it's a very localised phenomenon.
The interference is also present on 2m, but would certainly be inaudible
with an antenna placed well outside of the shack.

73 Stephen G4SJP

On 6 July 2011 21:20, K7WIA <[hidden email]> wrote:

> FWIW
>
> This morning we had a very good opening on 6 meters to the east coast Maine
> down to Florida from the PNW,
> When the band died, I thought it would be a good time to go out and snoop
> the neighborhood for the line noise source that bugs me, So i got out my
> MFJ Line Noise Meter, put it on the desk to put in a new battery. I
> turned
> it on and what a racket. so I snooped the shack and found it comes from the
> P3.
> turn the power off on the P3 and silence, I could get 30 feet away before
> I
> could not hear it any more.
> I don't hear any of the RFI on any band 160<>6. So I don't know if it is
> there on 2 meters, The MFJ receives on the Aircraft band around 137 MHZ. so
> I don't know if would effect 2 meters or not.
>
> Ed K7WIA
>
> --
> View this message in context:
> http://elecraft.365791.n2.nabble.com/P3-RFI-tp6555879p6555879.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
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John Ragle

Re: P3 RFI

List...

I am using a K3 with an XV144 to a TE brick, to a 5 el beam at 35
'. The P3 is atop the K3. There is no discernible change in receiver
noise level at the K3 listening on 50.100 when the P3 is on vs. off. I
also have an ICOM 910H sitting about 1.25 feet from the P3, and
listening on 144.200 there is no discernible change in noise level
between P3 on and off.

Be reassured...

John Ragle -- W1ZI

=====

On 7/6/2011 4:29 PM, Stephen Prior wrote:

> Ed,
>
> Listening on a TH-D72 on about 137MHz, yes the noise from the P3 is indeed
> loud. However, by the time I have more than a metre or so separation
> between the P3 and the handie, the noise drops below the handie's squelch
> threshold, so for me at least, it's a very localised phenomenon.
> The interference is also present on 2m, but would certainly be inaudible
> with an antenna placed well outside of the shack.
>
> 73 Stephen G4SJP
>
> On 6 July 2011 21:20, K7WIA<[hidden email]> wrote:
>
>> FWIW
>>
>> This morning we had a very good opening on 6 meters to the east coast Maine
>> down to Florida from the PNW,
>> When the band died, I thought it would be a good time to go out and snoop
>> the neighborhood for the line noise source that bugs me, So i got out my
>> MFJ Line Noise Meter, put it on the desk to put in a new battery. I
>> turned
>> it on and what a racket. so I snooped the shack and found it comes from the
>> P3.
>> turn the power off on the P3 and silence, I could get 30 feet away before
>> I
>> could not hear it any more.
>> I don't hear any of the RFI on any band 160<>6. So I don't know if it is
>> there on 2 meters, The MFJ receives on the Aircraft band around 137 MHZ. so
>> I don't know if would effect 2 meters or not.
>>
>> Ed K7WIA

John Ragle

sorry, typo..

In reply to this post by KD7PY

My previous message garbled. I was listening with the K3 and XV144 on
144.200 not 50.100 as advertized.

John Ragle -- W1ZI
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Jim Brown-10

Re: P3 RFI

In reply to this post by John Ragle

On 7/6/2011 1:39 PM, John Ragle wrote:
> I am using a K3 with an XV144 to a TE brick, to a 5 el beam at 35
> '. The P3 is atop the K3. There is no discernible change in receiver
> noise level at the K3 listening on 50.100 when the P3 is on vs. off.

Unless something is badly broken (bad cable shield, poor shielding, poor
design, like Pin One problems), what matters is the distance between the
noise source and YOUR RECEIVING ANTENNA. So to do a meaningful test of
noise originating in your shack, you would need to connect a short piece
of wire into the ANT input the rig and probe around for noise.

73, Jim K9YC
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Jim Brown-10

Re: P3 RFI

On 7/6/2011 5:10 PM, John Ragle wrote:
> Sorry, but your "test" is a test that has NO meaning whatever. Does a
> tree falling the forest make a noise if no one is there to hear it?

No, it is considerable meaning. The question was, is the P3 a noise
source? The test I described is a good way to learn that. Your test
(listen through the station antenna) is only useful if the station
antenna is very close to the P3. The fact that your antenna, at
considerable distance from shack, doesn't mean much to a guy whose
antenna is very close to his shack. I've had it both ways.

73, Jim K9YC
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John Lemay

Re: P3 RFI

In reply to this post by Stephen G4SJP

Good morning all

I raised the issue of noise coming from my P3 several months ago.

It is noticeable on 2m, using an EME array that is about 50ft from the rig.
There is a combination of azimuth and elevation in which the array "looks"
directly at my shack and under those circumstances the noise level on 2m
rises several dB.

I was advised to put chokes on the cables at the P3 end, and to revisit the
cleaning of metal panels on the P3 where they meet. I've done this till I'm
blue in the face, but it doesn't help because the P3 radiates a small amount
of hash from the display screen. It's not practical to screen this !

Regards

John G4ZTR

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Stephen Prior
Sent: 06 July 2011 21:29
To: K7WIA
Cc: [hidden email]
Subject: Re: [Elecraft] P3 RFI

Ed,

Listening on a TH-D72 on about 137MHz, yes the noise from the P3 is indeed
loud. However, by the time I have more than a metre or so separation
between the P3 and the handie, the noise drops below the handie's squelch
threshold, so for me at least, it's a very localised phenomenon.
The interference is also present on 2m, but would certainly be inaudible
with an antenna placed well outside of the shack.

73 Stephen G4SJP

On 6 July 2011 21:20, K7WIA <[hidden email]> wrote:

> FWIW
>
> This morning we had a very good opening on 6 meters to the east coast
Maine
> down to Florida from the PNW,
> When the band died, I thought it would be a good time to go out and snoop
> the neighborhood for the line noise source that bugs me, So i got out my
> MFJ Line Noise Meter, put it on the desk to put in a new battery. I
> turned
> it on and what a racket. so I snooped the shack and found it comes from
the
> P3.
> turn the power off on the P3 and silence, I could get 30 feet away before
> I
> could not hear it any more.
> I don't hear any of the RFI on any band 160<>6. So I don't know if it is
> there on 2 meters, The MFJ receives on the Aircraft band around 137 MHZ.
so

> I don't know if would effect 2 meters or not.
>
> Ed K7WIA
>
> --
> View this message in context:
> http://elecraft.365791.n2.nabble.com/P3-RFI-tp6555879p6555879.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

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database 6271 (20110706) __________

The message was checked by ESET NOD32 Antivirus.

http://www.eset.com

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database 6271 (20110706) __________

The message was checked by ESET NOD32 Antivirus.

http://www.eset.com

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Stephen G4SJP

Re: P3 RFI

Hi John,

I wasn't including EME antennas in my observations! That's a real nuisance.
Maybe a few atoms thickness of metal (Ni comes to mind) vacuum deposited on
the acrylic panel covering the display would help - in a former life I could
have done it for you!

It's worth a thought if it's that troublesome. Maybe Elecraft could look
into it.

73 Stephen G4SJP

On 7 July 2011 08:06, John Lemay <[hidden email]> wrote:

> Good morning all
>
> I raised the issue of noise coming from my P3 several months ago.
>
> It is noticeable on 2m, using an EME array that is about 50ft from the rig.
> There is a combination of azimuth and elevation in which the array "looks"
> directly at my shack and under those circumstances the noise level on 2m
> rises several dB.
>
> I was advised to put chokes on the cables at the P3 end, and to revisit the
> cleaning of metal panels on the P3 where they meet. I've done this till I'm
> blue in the face, but it doesn't help because the P3 radiates a small
> amount
> of hash from the display screen. It's not practical to screen this !
>
> Regards
>
> John G4ZTR
>
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Stephen Prior
> Sent: 06 July 2011 21:29
> To: K7WIA
> Cc: [hidden email]
> Subject: Re: [Elecraft] P3 RFI
>
> Ed,
>
> Listening on a TH-D72 on about 137MHz, yes the noise from the P3 is indeed
> loud. However, by the time I have more than a metre or so separation
> between the P3 and the handie, the noise drops below the handie's squelch
> threshold, so for me at least, it's a very localised phenomenon.
> The interference is also present on 2m, but would certainly be inaudible
> with an antenna placed well outside of the shack.
>
> 73 Stephen G4SJP
>
> On 6 July 2011 21:20, K7WIA <[hidden email]> wrote:
>
> > FWIW
> >
> > This morning we had a very good opening on 6 meters to the east coast
> Maine
> > down to Florida from the PNW,
> > When the band died, I thought it would be a good time to go out and snoop
> > the neighborhood for the line noise source that bugs me, So i got out
> my
> > MFJ Line Noise Meter, put it on the desk to put in a new battery. I
> > turned
> > it on and what a racket. so I snooped the shack and found it comes from
> the
> > P3.
> > turn the power off on the P3 and silence, I could get 30 feet away
> before
> > I
> > could not hear it any more.
> > I don't hear any of the RFI on any band 160<>6. So I don't know if it is
> > there on 2 meters, The MFJ receives on the Aircraft band around 137 MHZ.
> so
> > I don't know if would effect 2 meters or not.
> >
> > Ed K7WIA
> >
> > --
> > View this message in context:
> > http://elecraft.365791.n2.nabble.com/P3-RFI-tp6555879p6555879.html
> > Sent from the Elecraft mailing list archive at Nabble.com.
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:[hidden email]
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> >
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
> __________ Information from ESET NOD32 Antivirus, version of virus
> signature
> database 6271 (20110706) __________
>
> The message was checked by ESET NOD32 Antivirus.
>
> http://www.eset.com
>
>
>
>
> __________ Information from ESET NOD32 Antivirus, version of virus
> signature
> database 6271 (20110706) __________
>
> The message was checked by ESET NOD32 Antivirus.
>
> http://www.eset.com
>
>
>

gm3sek

Re: P3 RFI

In reply to this post by John Lemay

John Lemay wrote:

>Good morning all
>
>I raised the issue of noise coming from my P3 several months ago.
>
>It is noticeable on 2m, using an EME array that is about 50ft from the
>rig. There is a combination of azimuth and elevation in which the array
>"looks" directly at my shack and under those circumstances the noise
>level on 2m rises several dB.
>
>I was advised to put chokes on the cables at the P3 end, and to revisit
>the cleaning of metal panels on the P3 where they meet. I've done this
>till I'm blue in the face, but it doesn't help because the P3 radiates
>a small amount of hash from the display screen. It's not practical to
>screen this !
>
>Regards
>
>John G4ZTR

It seems rather unlikely to be a radiating EM field launched directly
out of the panel cut-out of the P3. The aperture is too small to act as
an efficient radiator at a wavelength of 2 metres, and the internal
noise source is unlikely to be driving it efficiently either.

It seems more likely to be starting out as conducted interference -
internal RF currents escaping perhaps through that hole or through other
defects in the shielding (which unfortunately are endemic in this 'flat
pack' style of construction). Those RF currents will then flow over the
outer surfaces of the metalwork and the connecting cables, and that
could be where the radiation is actually taking place.

Have you checked which of the cables are actually carrying the noise
currents? A clamp-on ferrite bead with a 10-turn secondary winding is a
very good diagnostic tool, coupled into a spectrum analyser or a totally
independent VHF receiver with an S-meter. Another option to use with the
clamp-on transformer is W7ZOI's AD8307 microwattmeter, which is so
sensitive it's scary.

An interesting experiment would be to blank off the entire screen
aperture with a metal plate, solidly grounded to the front panel, just
to see what difference it really makes. It obviously isn't a solution,
but it could be a useful as a diagnostic.

--

73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek
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Jim Brown-10

Re: P3 RFI

On 7/7/2011 3:19 AM, Ian White GM3SEK wrote:
> It seems rather unlikely to be a radiating EM field launched directly
> out of the panel cut-out of the P3.

I tend to agree with Ian's advice, and with that you received from
Elecraft. Following up on it -- suitable RF chokes for 2M would be Fair
Rite #43 cores, either solid cylinders or clamp-ons. Use the longest
parts you can find, do NOT wind multiple turns, but DO use multiple
cores in series on EVERY cable. Don't forget to choke the POWER cable.

73, Jim Brown K9YC
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