[OZAPRS] Fwd: [VK2-APRS] APRS interference issue

[vk5ex.andrew]

Good to see you up on the list Grant ,

Long time no hear.

catch up with you sometime ..

cheers .. Andrew .. VK5EX


----- Original Message ----- 
From: "Grant (VK5ZWI)" <vk5zwi at bigpond.com>
To: "Australian APRS Users" <ozaprs at aprs.net.au>
Sent: Friday, August 22, 2008 8:49 AM
Subject: RE: [OZAPRS] Fwd: [VK2-APRS] APRS interference issue


> That may be almost incurable. We had it here in Adelaide years ago
> and had to put it down to rusty bolts in the tower - as it came and went
> when we shook it (it was a 120ft free standing job).
>
> You will be very hard pressed to control it without one or other of the
> services changing frequency as anything non-linear on the site that can
> act as a diode can produce the mixing effect and have it reradiate around
> the site.  (I am assuming at this point that your WICEN repeater, UHF
> repeater and APRS digipeater are all colocated?)
>
> The case we had years ago was 147.575 mixing with 147.000 to produce
> 146.425 - only 25KHz above the repeater input. We ended up moving the 
> packet
> to 144.925 to get away from the problem.  Your mix is a little more
> complicated
> but being only first and second order can still be fairly easy to produce.
>
> Regards,
> Grant VK5ZWI
>
>
> -----Original Message-----
> From: ozaprs-bounces at aprs.net.au [mailto:ozaprs-bounces at aprs.net.au]On
> Behalf Of David Hardy
> Sent: Thursday, 21 August 2008 9:13 AM
> To: ozaprs at aprs.net.au; VK2-APRS at yahoogroups.com
> Subject: RE: [OZAPRS] Fwd: [VK2-APRS] APRS interference issue
>
>
>
>
> All,
>
> The cause of the issue has been found. It is a local intermod of our
> UHF repeater 438.075 - (2 x APRS) 290.350 = 147.725 our WICEN repeater
> input.
> Now the task is to find out where it is coming from!
>
>
> Dave
>
>
> (Receivers and Managers Appointed) (Administrators Appointed
>
> -----Original Message-----
> From: ozaprs-bounces at aprs.net.au [mailto:ozaprs-bounces at aprs.net.au] On
> Behalf Of Damien Gardner Jnr
> Sent: Wednesday, 20 August 2008 4:59 PM
> To: Australian APRS Users
> Subject: [OZAPRS] Fwd: [VK2-APRS] APRS interference issue
>
> Forwarded to ozaprs, as I dont' think anyone uses the vk2-aprs list ;)
>
> Begin forwarded message:
>
>> From: "vk2ydh" <vk2ydh at terrigal.net.au>
>> Date: 20 August 2008 4:54:17 PM
>> To: <VK2-APRS at yahoogroups.com>
>> Subject: [VK2-APRS] APRS interference issue
>> Reply-To: VK2-APRS at yahoogroups.com
>>
>> Hi,
>>
>>  I'm from the Central Coast ARC and we are getting APRS packets on our
>
>> WICEN VHF Repeater 147.125 TX and 147.725 MHz RX at Somersby.
>>
>>  The packets are mainly 07:45 - 08:15 and 4:45 - 5:15PM and
>> intermittent through the day and night.
>>
>>  We are receiving a strong signal at Somersby on 147.725 MHz (repeater
>
>> input) it can't be heard at Kanwal and we are attempting to track down
>
>> the source.
>>
>>  Can people  check to make sure they are not inavertantly txing on out
>
>> repeater input?
>>
>>  Regards,
>>
>>  Dave Hardy
>>  vk2jdh
>>
>>
>>  Sample packet dump of rx.
>>
>>  Mon Aug 18 08:13:01 2008 - 4700 recv:
>>  KISS: Port 0 Data
>>  AX25: VK2INT-5->APU25N v VK2RAG-1* INETNC UI pid=Text  0000
>> }VK2RBX-1>APNU19,TCPIP,VK2INT-5*:!3412.65SS14215.84E#PHG5330/W2
>>  0040  APRS Digi - Mildura - (2).
>>
>> [Non-text portions of this message have been removed]
>>
>>
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>
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