Thanks for the info George. I have watched your video….very FB indeed. Using the 74HC244 line driver/buffer as a PA is a great idea. I had heard of this idea before, but never found a circuit. Jim, WA9VEZ put me on to this design which gives good detail and output matching ideas. https://circuitsalad.com/2015/07/23/1-watt-qrp-rf-amp-using-74ac240-or-74ac04-inverter/ <https://circuitsalad.com/2015/07/23/1-watt-qrp-rf-amp-using-74ac240-or-74ac04-inverter/> It’s great to get detail from someone who has already built up the circuit and done the experimenting. This will be a fun project for the next few weeks.
This fellow, Ray Ring has an amazing blog with a gold mine of circuit ideas and design. He is bookmarked on my computer now! https://circuitsalad.com/ <https://circuitsalad.com/> 73, de steve ve6wz > On May 3, 2021, at 7:17 AM, GEORGE WALLNER <[email protected]> wrote: > > Hello Steve, > > I have built exactly what you are looking for: a small 200 mW transmitter > that can be attached to a drone (including battery). > > For the "PA" stage a I used a 74HC244 buffer, with all the gates paralleled, > feeding a resonant tank wound on a ferrite rod, which is also the antenna. > The battery is a single 3.7 V 500 mAhr LiPO. My -30 dBi two element loaded > loop array can "hear" it from about half a mile, far enough to do RX antenna > pattern measurements. > > See : https://www.youtube.com/watch?v=JMujut_5FdY > <https://www.youtube.com/watch?v=JMujut_5FdY> > > GL and 73, > > George > > AA7JV/C6AGU > > > > > > On Sun, 2 May 2021 18:46:49 -0600 > > VE6WZ_Steve <[email protected]> wrote: > > For field testing, I’m looking for some ideas for a very small RF amplifier > to boost the output from a HCMOS 1.843 MHz oscillator. > > These oscillators will give me about 20 mW max, but I need a bit more since I > plan to mount it on my small drone and will need a bit more range. > > My drone can lift up 130 grams, so I’d like it to run on a 5v supply. (maybe > a 9v battery with regulator or 3 AAA cells) > > > I considered something like a Mini Circuits PHA-13ln 21 dB monolithic amp, > but not sure thats such a good idea. > > A 2N5109 base amp is a current pig and too heavy. > > > Any ideas? > > > 73, de steve ve6wz > > > > _________________ > > Searchable Archives: http://www.contesting.com/_topband > <http://www.contesting.com/_topband> - Topband Reflector > > _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
