[OZAPRS] Brave new Move!!

[Tony Hunt]

Gday Norm.. I guess your down on 40m still .. I will QSY the radio in a
while and check it out ..

On the subject of RF on HF getting into things .. I recently managed to
solve a huge problem .. The RF was getting back into the PTT line and into
the radio ..

I allready had a audio transformer on the Mic audio input .. This helps
alot
.. Some radios have a separate earth/Gnd connection for the Mic in as
opposed to PTT ground.. The idea is to DC isolate the Mic inputs.. Often
just using a series
capacitor acheives nothing except to pass the RF to the Mic input .. The
cheap audio transformers 3k-1k or even a pair of back to back 1k-8ohm are
lousy at passing RF but reasonable with audio ..

I too tried alot of clipon ferrites etc here and there but didnt win much
with that approach.. I disconnected the PTT input and manually keyed the
radio to find that it cleared the problem. The best fix was a 1mH RF Choke
in series with the PTT line near the radio.. I tried all sorts of RF
bypass
and this did basically nothing in comparison to the RFC .. I can now run
100w out as compared to 5w out before the RFC mod ..

This is a TS680 radio with a PK232 TNC and a 40m long OCF dipole ..

Tony VK5AH

----- Original Message -----
From: "Norm McMillan" <njmcmillan at bigpond.com>
To: "OZAPRS" <ozaprs at marconi.ics.mq.edu.au>
Sent: Friday, November 26, 2004 5:56 PM
Subject: [OZAPRS] Brave new Move!!


> G'day all,
> I'm going to leave the HF  and VHF digis running overnite. This is a
> brave move as I'm not sure how reliable the rigs, computer and mains
> supply is! (are?) It has to be done eventually I guess
>
> The VHF digi is currently on 144.700, the old ARRG APRS frequency,
> absent crystals for 145.175 for the 828. Work in progress.
>
> The mobile and Tinytrak 3 in my ute has a problem. Extreme noise on the
> tx audio. Sounds like alternator whine but not present on Rx audio! Same
> is true for UHF CB in the ute. It is bad enough to b----r up the packet
> tones!
>
> I have reduced it with ferrites etc on the power lead but obviously more
> to be done. Suggestions are canvased
>
> 2002 Rodeo V6 EFI
> Yaesu FT480-R
> ICOM IC 215
> Electrophone TX472S
>
>
> --
> Norm, VK2XCI,
> Voice of The Edge of The Outback.
> QF27wd
> _______________________________________________
> ozaprs mailing list
> ozaprs at marconi.ics.mq.edu.au
> http://marconi.ics.mq.edu.au/cgi-bin/mailman/listinfo/ozaprs
>

_______________________________________________
ozaprs mailing list
ozaprs at marconi.ics.mq.edu.au
http://marconi.ics.mq.edu.au/cgi-bin/mailman/listinfo/ozaprs