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Old 26th Jun 2018, 8:16 am   #8
Join Date: Jun 2018
Location: Schoonebeek, The Netherlands
Posts: 1
Default Re: Trio TS711 low or no RF power output

Hello Simon,

Had also trouble here last week with my TS711.
After not used for 3 years, I finally found the time to start back my HAM hobby.
Then I discovered the set did not had any output on the power-meter. I connected a more sensitive meter and got only 50mW.
It did transmit at the correct frequency and RX was still OK.
I checked the PA-module which turned out to still amplify 24dB or so.

I found your thread and because I had no further ideas were to start the repair, I simply changed all the capacitors in the first table you posted (from cereamics to NP0 SMD because I had these in all values in stock).
NO LUCK....not improvents, still 50mW.

Then I measured the 'HET' signal which is mixed with the 'TIS' signal and found the 'TIS' suspiciously low in amplitude. This 'TIS' signal is is controlled in amplitude by a FET in the IF-Unit. I checked and adjusted the DC control signal at this FET but still no improvement.

Following the adjustment procedure in the service manual, I skipped the PLL part and jumped into the adjustment of the IF_Output level as described under chapter TS-711 A/E TX Section;
I adjusted pot VR7 to maximum which increased the power of the tranceiver to 150mW. Then I slowly adjusted L6 and L7 which were already close to the maximum, but as I adjusted L8, L9 and L10....the output of the transceicer was way up to 30W or so! To limit the output power back to the desired 25W I quickly closed VR7 potmeter.

What I mean to say with this: Possibly after 7 hours you may loose some output due to L8, L9 and L10 not exactly at the correct adjustment anymore.
In my case I returned from 50mW back to 25W by simply re-adjusting these.
I almost start the search for another tranceiver to replace mine, but luckely it was just a matter of tuning the cores in the TX section of the IF-board.

Let me know if this was helpful to you...
At least I could make 2 new initial EME QSO's last night now the old trusty TS-711 is back in action.

Gerrie, PA3EXV
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