[TheList] T500 TX issue

Thu Mar 25 07:39:21 AEDT 2010

Morning Neill,

We have to keep scheming...no point getting out of bed if we don't.
S curve is tracked at the FM detection point...generally the processor
changes to that mode after AGC conditions are met. 
Looks for zero crossing on the ratio detector and then tracks that...

Have to find a can that has no first IF built in as it will be way to wide
for our type of work...200Khz for wide fm work if I recall...

Shane.

-----Original Message-----
From: thelist-bounces at radiowiki.org.nz
[mailto:thelist-bounces at radiowiki.org.nz] On Behalf Of Neill Ellis
Sent: Tuesday, 23 March 2010 7:14 a.m.
To: thelist at radiowiki.org.nz
Subject: Re: [TheList] T500 TX issue

Hi Shane,

I keep meaning to acquire some 76-90MHz jap import radios to get the 
tuner modules out of them. Intention being to build a dual receiver 
based around them. The S meter may be a challenge as I doubt they will 
have any form of AGC.

It's in it's dying days but I'm still schemeing.

Most Motorola stuff 10 years ago was based on a 14.4 MHz reference, so 
seeing 7.2 doesn't surprise me.

Regards,

Neill.

Shane V wrote:
> Awesome report...This makes for great reading....Thanks Neil..
>
> Auckland is lucky in one advent I guess, being last to move
> digital...Listening in for some light back ground chatter will be
> missed by me also...Still have fire and ambo chatter for the time being I
> guess
>
> Auckland has a colourful life on the edacs trunking channels from what I
> recall...may have to resurrect my 800 MHz antennas..
>
> My tech time is with domestic tuners...everything is processor controlled
> with a PLL being controlled by AGC feedback and s curve
> tracking for final lock...One rock on 7.2 MHz to look after everything to
do
> with tuning.
>
> I have a RCA portable in front of me that used to be police many moons
> ago...I can't bring myself to pass it on or throw it out..
> It still has a label with Rotorua Temp on it.  All D band channels I seem
to
> recall.
> It is set up with crystals RX and TX for the eight possible channels...It
> still works too....
>
> Nice to see us flare up again 
>
> Cheers guys..
>
> -----Original Message-----
> From: thelist-bounces at radiowiki.org.nz
> [mailto:thelist-bounces at radiowiki.org.nz] On Behalf Of Neill Ellis
> Sent: Sunday, 21 March 2010 9:30 a.m.
> To: thelist at radiowiki.org.nz
> Subject: Re: [TheList] T500 TX issue
>
> You are obviously lucky enough to not be familiar with them. There is a 
> multichannel kit that can scan, but there weren't many made and it's a 
> painfully slow scan as the PLL doesn't lock very quickly. I don't know 
> of any voting on T500's except perhaps the control channel antics on the 
> T555TR.
>
>
>
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>   

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