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R: Question about interaction between separate rigs for Mode U/V sat ellite operations



Hi Jim, N8AU

Ray is using his 2 meter rig for receiving OSCAR-7 at 145.950 MHz
in Mode-B and  the 3rd harmonic of his TX at 432.150 MHz been higher in
frequency cannot fall belove at 144.950 MHz

What you states would be correct transmitting in 2 meters and receiving
in 70 cm wich is not the case because Ray is working mode V/U with
Fuji-OSCAR-29 without any interaction.

Best 73" de

i8CVS Domenico

----- Original Message -----
From: Reicher, James <JReicher@hrblock.com>
To: i8cvs <domenico.i8cvs@tin.it>; Fritts, Raymond C. (CONTR) (L)
<rfritts@jiatfs.southcom.mil>; Lau, Zack, W1VT <w1vt@arrl.org>; amsat bb
<amsat-bb@AMSAT.Org>
Sent: Thursday, December 02, 2004 8:12 PM
Subject: RE: [amsat-bb] Question about interaction between separate rigs for
Mode U/V sat ellite operations


> I would better believe that Ray is experiencing interference from his
> own rig due to the fact that 432.15 is the 3rd harmonic of 144.05.  His
> 2 meter receiver just can't reject the signal.
>
> Ray, have you tried a low-pass filter on your 2M rig and a hi-pass
> filter on the 70 cm rig?
>
> 73 de N8AU, Jim in Raymore, MO
>
> -----Original Message-----
> From: owner-AMSAT-BB@AMSAT.Org [mailto:owner-AMSAT-BB@AMSAT.Org] On
> Behalf Of i8cvs
> Sent: Thursday, December 02, 2004 8:20 AM
> To: Fritts, Raymond C. (CONTR) (L); 'Lau, Zack, W1VT'; 'amsat bb'
> Subject: R: [amsat-bb] Question about interaction between separate rigs
> for Mode U/V sat ellite operations
>
> Hi Ray, KA8SYX
>
> From your story of the "hot spots" it seams that your 2 meter coax cable
> is connected to an antenna wich dipole has not a good balun so that in
> this condition the radio frequency flows also over the external surface
> of the braid of the coax cable wich in turn functioning as an unwanted
> antenna pick up a lot of signals from everywere even from the case of
> your FT 290 R
>
> Please disconnect the 2 meters coax cable from the antenna dipole and
> replace the 2 meters antenna with a good 50 ohm termination and see if
> the interference disappear or not.
>
> If  you are still receiving the interference than connect the 50 ohm
> termination directly to your 2 meter receiver and see what happens
> particularly looking if the "hot spots" if they are still present have
> the
> same strenght with your hands engaged as before.
>
> Hopefully the above simple procedure will permit you to identify
> step by step a little more about the source of your problem.
>
> Best 73" de
>
> i8CVS Domenico
>
> ----- Original Message -----
> From: Fritts, Raymond C. (CONTR) (L) <rfritts@jiatfs.southcom.mil>
> To: 'Lau, Zack, W1VT' <w1vt@arrl.org>; 'amsat bb' <amsat-bb@AMSAT.Org>
> Sent: Wednesday, December 01, 2004 4:21 PM
> Subject: [amsat-bb] Question about interaction between separate rigs for
> Mode U/V sat ellite operations
>
>
> > Hi, Zack,
> >
> > Thanks for your reply and suggestions.  I realize this may not be the
> > proper avenue to continue this discussion because "Ask the Doctor" is
> > basically a one-question-at-a-time forum, but wanted to inquire
> further
> > about my problem.  I also hope that you do not mind if I open it up to
> > discussion on AMSAT BB.  I can use all the advice anyone might have.
> >
> > Taking your advice re: notch filters I stopped off at the local RS in
> Key
> > West on the way home from work last night and picked up a BNC T
> adapter
> > and short plug-equipped RG-58 jumper.  I attached the T to the input
> of
> > the 2M 3-el portion of my Arrow II crossed dual band Yagi, clipped the
> > RG-58 jumper to what I'd calculated (Vf of .66 and 234 as the
> denominator
> > of the freq/n equation for deriving physical length of a 1/4 wave) as
> the
> > 1/4wave length for 432.15 (AO-7 uplink band center, worked out to be
> about
> > 109mm,) left the far end open and connected it to one side of the T,
> the
> > feedline to the 2M receiver to the other side of the T and the male
> bottom
> > of the T to the Yagi as described above.  I fired the whole business
> up
> > and transmitting 2.5W PEP from the 70cm rig, still heard the
> interference
> > on the 2M receiver.  No reduction whatsoever.
> >
> > Some things I noticed about the whole issue that I didn't lay out in
> > earlier email:
> >
> > -It's not an issue in FM, only in phone and CW.  On CW, the
> interference
> > is a clicking sound on key make but not break and no tone heard.
> > -My HT, transmitting into the 70cm Yagi on 70cm FM, has no effect.
> > -No matter whether the frequency difference between my 70cm
> transmissions
> > and 2M receptions is, and regardless of changing one rig's
> frequency/mode
> > or the other during transmission, the pitch and quality of the
> > interference as received on the 2M receiver remains unchanged.
> > -There are "hot spots" on the 2M receiver's case where the received
> > interference signal is much stronger.  Of course, this is with the
> 70cm
> > mike in one hand, PTT engaged, with headphones from the 2M receiver on
> my
> > head and the other hand on the hot spot; I'm trying to duplicate the
> > operating condx during normal satellite use.  The hot spots are on the
> > mobile mounting brackets of the 2M receiver to either side and
> slightly
> > behind the front panel.  I touch those while transmitting and I cannot
> > hear anything in the headphones except the interference.  But I cannot
> > remove them during use because that same bracket is where the clip-on
> > linear amps attach.
> > -When I purchased the 70cm rig, used, it had a single wire dangling
> from
> > the case through a small hole drilled in it; it was the result of a
> mod
> > the first owner had installed to enable CTCSS because he didn't have
> the
> > Yaesu model and used an external CTCSS coder box.  Thinking the
> exposed
> > wire was radiating the interference from the location in the rig's
> > circuits to which it was attached, I clipped it at it's junction; I
> don't
> > care one bit about CTCSS for this rig; strictly weak sig stuff was why
> I
> > got it.
> >
> > Anyway, that's the story.  If you have any other suggestions/advice,
> I'm
> > awfully glad to hear it.  Again, thanks!
> >
> > Vy 73, Ray Fritts KA8SYX
> > Big Pine Key, FL
> >
> > -----Original Message-----
> > From: Lau, Zack, W1VT [mailto:w1vt@arrl.org]
> > Sent: Monday, November 29, 2004 3:56 PM
> > To: rfritts@jiatfs.southcom.mil
> > Subject: RE: Question about interaction between separate rigs for Mode
> U/V
> > satellite operations
> >
> >
> > Hi Ray,
> > Mike Tracy fowarded your puzzler my way.  Sorry for the delay in
> > replying--I was
> > on vacation last week.
> >
> > I suggest attempting to obtain another 2M receiver or another 70
> > cm transmitter.
> > The 70 cm transmitter could be an FM handie talkie.  This may allow
> you
> > to determine
> > whether the problem is the receiver or the transmitter.  As it stands,
> > it could be either.
> > You could need
> >
> > My guess is that the 2M receiver is the culprit.  The 2M antenna
> > is also resonant
> > on 70 cm, so it picks up 70cm signal with little attenuation.
> > Typically, receiver
> > input circuits are designed for maximum sensitivity--spurious
> responses
> > aren't unusual.
> > I suggest putting a notch filter for 70 cm--with a Tee connector add a
> > quarter wave open
> > stub cut to 70 cm.
> >
> > http://www.ifwtech.co.uk/g3sek/swxfiltr/swxfiltr.htm
> > more complicated notch filters
> >
> > 73--Zack Lau W1VT
> >
> >
> > > -----Original Message-----
> > > From: Tracy, Michael, KC1SX
> > > Sent: Wednesday, November 24, 2004 3:16 PM
> > > To: TIS Unsorted
> > > Subject: FW: Question about interaction between separate rigs for
> Mode
> > > U/V satellite operations
> > >
> > >
> > >
> > > -----Original Message-----
> > > From: Fritts, Raymond C. (CONTR) (L)
> > > [mailto:rfritts@jiatfs.southcom.mil]
> > > Sent: Monday, November 22, 2004 10:52 AM
> > > To: TIS Unsorted
> > > Cc: 'ka8syx@arrl.net'
> > > Subject: Question about interaction between separate rigs for
> > > Mode U/V satellite operations
> > >
> > >
> > > Dear Doctor -
> > >
> > > I'm hearing transmissions from my 70cm allmode rig (Yaesu
> > > FT-790R MkII,) used to attempt uplinking to AMSAT-OSCAR-07,
> > > on my 2M downlink rig (Yaesu FT-290R MkII.)  I've tried a
> > > number of experiments, including the use of a homebrewed
> > > 432.1MHz Yagi physically separated from my 2M downlink Yagi,
> > > oriented to minimize interaction, running the rigs with
> > > different power supplies (batteries v. mains, separate
> > > batteries, etc.), physically separating the radios by a foot
> > > or so, separating the antennas, running the 70cm rig at 1/10
> > > the power, and/or into a dummy load.  Thinking that the
> > > problem may be caused by interaction between the 70cm and 2M
> > > elements on my Arrow II crossed dual-band Yagi, I even tried
> > > removing the 70cm elements and just used the 2M elements
> > > alone along with the homebrewed "cheap Yagi."  To a greater
> > > or lesser extent, the interference was still there no matter
> > > what I tried.  It intensifies when I have my hand on or in
> > > close proximity to my transmitting 70cm rig.  Over the past
> > > few months I've become increasingly familiar and successful
> > > at operating on the Mode V/U sat, Fuji-OSCAR-29, with no
> > > interaction whatsoever on that mode; I'm fortunate; I've not
> > > even experienced problems with desensing in the receiver.
> > > But this interaction between my 70cm uplink and 2M downlink
> > > in Mode U/V was totally unexpected, and it prevents me from
> > > finding my downlink signal, even when my pass predictions
> > > suggest that, for all of the predicted attributes, I should
> > > be in the ballpark and hear myself.  What is causing this
> > > problem?  Is there a cure?  If so, what must I do to correct it?
> > >
> > > Thanks very much, and 73,
> > > Ray Fritts, KA8SYX
> > > Big Pine Key, FL
> >
> > [demime 1.01d removed an attachment of type
> application/x-pkcs7-signature
> which had a name of smime.p7s]
> > ----
> > Sent via amsat-bb@amsat.org. Opinions expressed are those of the
> author.
> > Not an AMSAT member? Join now to support the amateur satellite
> program!
> > To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
> ----
> Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
> Not an AMSAT member? Join now to support the amateur satellite program!
> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
> ----
> Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
> Not an AMSAT member? Join now to support the amateur satellite program!
> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
----
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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