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Simon_V · 20th May 2018, 11:35 pm

I think I can finally call this fixed!

Feeling like a bit of a twonk because I lost sight of something really important.

If your power supply voltages are not right then pretty much nothing else will be either.

I did originally set all the voltages but as I have increased the power coming from the RF board I had not re-checked them and as the current being drawn has increased the closer the RF board came to giving the correct 0.3 W so the 9T (9 volts) rail was not able to maintain a steady regulated 9 volts on this rail. I did a few tests and its pretty easy to loose 10 watts in the blink of an eye if you reduce this rail to 8.5 volts.

If you have got up to where I was with 25 watts from cold that falls away without the radio in TX but just switched on then change C10 - 100uF 16v in the AVR unit. Something else I discovered that is important, if your messing around with the RF board (something I have done a lot of) each time you test make sure you have put the 6 screws back in this board and they are tight, the board does some strange things if it's not earthed.

This was not the root cause of the problems. As I said I bought this radio knowing it had an RF power issue and I started out with well under 1 watt. Changing all the ceramics I have listed (which potentially could be 30 years old) has given gradual increases in RF output.

So my final measurements tonight, with the radio far warmer than I would like any radio to be, full power 22.5 watts and stable. cooled down naturally and with a room temperature of 67 deg F 26 Watts and rock stable.

Onwards and upwards, I will start new topics for these. The previous owner complained that the radio was deaf and was using it with a pre-amp. I don't find that to be so, I can hear a Repeater that is some 60 miles away OK. It doesn't move the S meter but it does break the squelch. My friend Don GW0PLP who is some 30 miles away just about lifts the S meter to S2, on my Yaesu FT7900 on the same antenna he shows S7. We have an SSB net here on Thursday evenings and I know I am off frequency by about 4 or 5 KHz on SSB on RX & TX.

Regards

Simon - GW6TKK

20th May 2018, 11:35 pm	#7
Simon_V Retired Dormant Member Join Date: Feb 2014 Location: Pembrokeshire, UK. Posts: 52	Re: Trio TS711 low or no RF power output I think I can finally call this fixed! Feeling like a bit of a twonk because I lost sight of something really important. If your power supply voltages are not right then pretty much nothing else will be either. I did originally set all the voltages but as I have increased the power coming from the RF board I had not re-checked them and as the current being drawn has increased the closer the RF board came to giving the correct 0.3 W so the 9T (9 volts) rail was not able to maintain a steady regulated 9 volts on this rail. I did a few tests and its pretty easy to loose 10 watts in the blink of an eye if you reduce this rail to 8.5 volts. If you have got up to where I was with 25 watts from cold that falls away without the radio in TX but just switched on then change C10 - 100uF 16v in the AVR unit. Something else I discovered that is important, if your messing around with the RF board (something I have done a lot of) each time you test make sure you have put the 6 screws back in this board and they are tight, the board does some strange things if it's not earthed. This was not the root cause of the problems. As I said I bought this radio knowing it had an RF power issue and I started out with well under 1 watt. Changing all the ceramics I have listed (which potentially could be 30 years old) has given gradual increases in RF output. So my final measurements tonight, with the radio far warmer than I would like any radio to be, full power 22.5 watts and stable. cooled down naturally and with a room temperature of 67 deg F 26 Watts and rock stable. Onwards and upwards, I will start new topics for these. The previous owner complained that the radio was deaf and was using it with a pre-amp. I don't find that to be so, I can hear a Repeater that is some 60 miles away OK. It doesn't move the S meter but it does break the squelch. My friend Don GW0PLP who is some 30 miles away just about lifts the S meter to S2, on my Yaesu FT7900 on the same antenna he shows S7. We have an SSB net here on Thursday evenings and I know I am off frequency by about 4 or 5 KHz on SSB on RX & TX. Regards Simon - GW6TKK