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Old 16th May 2018, 11:04 pm   #6
Simon_V
Retired Dormant Member
 
Join Date: Feb 2014
Location: Pembrokeshire, UK.
Posts: 52
Default Re: Trio TS711 low or no RF power output

Now this is significant so I thought I had better report it.

Something is still ultra temperature sensitive, not talking artificial warming or cooling just the ambient air temperature in the radio produced by being switched on.

I was monitoring the effects of this and writing down the results suspecting the varicap diode D7 which is connected to 9v on TX and CV which is a correction voltage from the PLL and still applies around 2v to this diode even in RX. The CV voltage is rock stable by the way.

While I had the board out I did a job I had been meaning to do which was change the 3 surface mount decoupling capacitors under L14 - L17 which are C29, C35 & C43 all 0.001uF.

The replacements are modern low ESR types and have made a huge difference. After some careful re-aligning I had 25 watts which I expected would reduce to about 10 watts if I left the radio on. Not so, some 7 hours later with all the covers on and I still have 20 watts.

Just need to find where the missing 5 watts are going now!


Regards


Simon GW6TKK
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