As some of you know the old DX33HML went out of production on Nov. 2006 and later replaced with the new DX33HP model. The only real changes made was the switch over to IRF520 mosfets, heavier AM modulator (2SB827) and blue leds. One characteristic of the IRF520 mosfet is the higher gain (hFE) at 25-29Mhz over the 2SC1969 bipolar transistors. Here is a tech tip that will increase peak power on the DX33HP models and not void the factory warranty.
This update will allow you to set the max carrier @ 10 watts with peaks of 50+ watts and no flat-topping on the scope.
Locate resistor R178 and replace it with a 1k ohm 1/4 watt.
See thumbnail below.
Next is the lack of a dimmer control on the DX33HP. The next production should have a dimmer control installed. Until then on the current production models you can replace jumper J303 on the channel PCB with a 1k ohm 1/4 watt resistor which works great for both day and night. This update also does not void the factory warranty and is recommended especially for night driving. See thumbnail below for the location of J303.
This update will allow you to set the max carrier @ 10 watts with peaks of 50+ watts and no flat-topping on the scope.
Locate resistor R178 and replace it with a 1k ohm 1/4 watt.
See thumbnail below.
Next is the lack of a dimmer control on the DX33HP. The next production should have a dimmer control installed. Until then on the current production models you can replace jumper J303 on the channel PCB with a 1k ohm 1/4 watt resistor which works great for both day and night. This update also does not void the factory warranty and is recommended especially for night driving. See thumbnail below for the location of J303.