[TheList] T500 TX issue

Sat Mar 20 18:35:17 AEDT 2010

Good to hear.

If the signal is strong enough, just doing the VCO adjustment will 
possibly be all that's needed. Otherwise, get closer to the signal and 
try the adjustments one at a time. Avoid the coil by the diode matrix 
(frequency) and the VCO coils. otherwise if it's being used just as a 
receiver, if it improves the signal adjust it for best receive. as the 
receive improves reduce the signal buy using a poorer aerial or moving 
further from the transmitter. The adjustments are just in front of the 
transmitter shield at the back of the radio, they run in a line parallel 
to the front of the shield.

Regards,

Neill.

Z-master wrote:
> Hey Neill thanks for the reply,
>
> Yeah mate, was pretty surprised myself haha.  Was more a spur of the 
> moment purchase than anything in all honesty...
>
> I have set the pot for 4.25V, its extremely touchy so thats probably 
> as close as I might get.  Unfortunately I don't know how to 'peak'  a 
> receiver,  sounds technical haha.
>
> Also, that VHF t500 is going extremely well, since you looked at it.  
> Hasn't missed a beat since!!
>
>  Richard
>
> On 20/03/2010 5:00 p.m., Neill Ellis wrote:
>> LOL, Vote or scan mode in a T500 :o)
>>
>> A brand new T500? That's sad, that unit is 20+ year old technology 
>> now and the stopped production well over 10 years ago.
>>
>> the T550 or T555 UHF versions can only do 12.5 kHz steps, so they 
>> can't receive new narrow simplex channels and can't transmit on new 
>> narrow repeater input frequencies.
>>
>> You not only need to clip the diodes, it will also need alignment. 
>> There are three vertical pins between the die cast VCO can on the PCB 
>> and the diode matrix PCB. Measure the voltage on the center pin 
>> relative to ground. You need to adjust the VCO for 4 volts on a 
>> single channel. On Multi channels try to keep the voltage close to 4 
>> volts but not outside the 1 and 7.5V range if it varies a lot. Of 
>> course you'll then need to peak the receiver too.
>>
>> Regards,
>>
>> Neill.
>>
>>
>> Shane V wrote:
>>> You may be seeing one of the LO's ramping if the unit is in vote or 
>>> scan
>>> mode...
>>>
>>> -----Original Message-----
>>> From: thelist-bounces at radiowiki.org.nz
>>> [mailto:thelist-bounces at radiowiki.org.nz] On Behalf Of Z-master
>>> Sent: Saturday, 20 March 2010 3:02 p.m.
>>> To: thelist at radiowiki.org.nz
>>> Subject: Re: [TheList] T500 TX issue
>>>
>>> Sorry team,  stand down.  Seems the units giving out interference 
>>> that I was picking up, it wasn't TXing at all (thankfully)
>>>
>>> Unit still won't RX frequencies so might take it in and get it checked.
>>>
>>> But to answer your other question, it shouldn't be TXing at all as 
>>> i've only snipped the RX1 and 2 diodes.
>>>
>>> Cheers
>>>
>>>
>>>
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>>
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