There are suggestions to set the FT817 to get the maximum possible output of 15 Watts from an FT817, but I consider this similar to believing in Santa Claus – do you really believe that Yaesu would overdesign the Filters, Relays and Power feeds to cope with THREE times as much power as they advertise the unit for ?
The 15 watt mod also totally disables the DC current limiting. Expect to see charred coils, DC filters and PC board next time you look inside your rig – a fan on the heatsink won’t stop this. For a rig that has no over-temperature indication or protection of any sort, tripling the power level is designing for disaster.
This procedure here will increase power to 10 watts on HF bands only, but ensures that the DC Over-current protection will reduce power into abnormal loads that the SWR detector cannot detect. SWR bridges are a only a compromise at detecting reflected power – that’s why Yaesu went to the effort of building in DC Over-current protection as well as high-SWR protection.
Here is the recommended procedure, you will need a Dummy Load and a Wattmeter or RF Voltmeter. Make a note of your original calibration settings so you can go back to the standard setting later – the easiest way to do this is to use FT817 Commander freeware. It is also easy to accidentally change a value by bumping the Dial knob, and you need to be able to get back to the original setting.
If you have a Key connected, set the VFO to CW on 1.8, 7 and 21 MHz bands – if you don’t have a Key, then set them to PKT and you will be able to get full carrier using Mic PTT but with no modulation going out.
Turn the radio off. Press and hold the three A, B, C buttons and press the PWR button. To change to a different Menu item turn the small SEL knob. To change the value of the item, turn the large Dial knob. Be careful not to bump the Dial knob so you don’t accidentally change settings..
- Increase HF1-IC to 150.
- Increase HF1-HI for an output of 14 watts - you will need at least 12 volts input.
- Decrease HF1-IC until you get 12 watts output
- Now set HF1-HI for 10 watts output.
- Repeat for HF2 and HF3
You could also change HF1-L3 to 5 watts to save battery drain when 10 watts isn’t needed.
If you are using an RF Voltmeter the readings are 0.5W=5v 1W=7v 2.5W=11v 5W=16v 10W=22v 12W=24v 14=26v.
To avoid de-calibrating the Voltmeter, set your supply to 13.8 volts – otherwise if you just flick over the DC volts position (Item 17 - VCC) you will recalibrate it.
To save these changed settings, hold the F button for two seconds when finished.