@@rfburns3472 Yes i will probably upload a video when i get it.. Im building an portable QRP rigg with a small T9 keypad for writing morse code and a Morse code encoder. Will use the malachite SDr for recieving signals and a si5351 VFO to generate the signal... But one worry i have is how much power do I need to use this amp? How much power do you feed it with, with your signal generator? i Think my VFO can give around 8mW max.. Im going to aim for the 30m band.. not sure yet.
@@JimCoupeTQ Looking forward to your video Silvanus. Regarding the drive required from you VFO, here is what the manual states. RF PA mode "The operating frequency of the power amplifier is 5MHz‐9MHz, the input power is 0dBm." That would only be 1 mW. So your VFO should work just fine.
I agree. I followed the kit's instructions for winding the 2 toroidal output transformers and ended up with the same results (twice) for 40 meters. I have not tried raising the supply voltage beyond 13.8. I might try 15.0 as maximum. 73's
Nice simple design and interesting video series. Thanks for posting. You are using the IRF530. Did you think about using the IRF510. That is a somewhat lighter FET and although you might think a lighter FET will run warmer, it may actually stay cooler. A lighter FET has lower capacitances and at higher frequencies gives you lower switching losses. Your output power won’t benefit much but when I see a heatsink like that with a fan for just a few watts I think there is certainly room for improvement in losses. One other thing which comes to my mind is the output low pass filter. When it symmetrical in C and L values on input and output the impedance will be the same (50 ohm) at the antenna and FET side. The FET side has its voltage swing as dictated by the supply voltage and the 50 ohms. That gives you a certain power level. If you make your filter asymmetrical it can offer a different input and output impedance. Say you change the filter in such a way that the FET side sees 25 ohms. With the same voltage swing you get a higher power. You noticed that already when you played with the C values but you could use some design rules or tools and optimize this.
Thanks for upload.. i just bought one assembled for my project.
YW .... Almost bought the assembled unit myself. Please let us all know how it performs.
@@rfburns3472 Yes i will probably upload a video when i get it.. Im building an portable QRP rigg with a small T9 keypad for writing morse code and a Morse code encoder. Will use the malachite SDr for recieving signals and a si5351 VFO to generate the signal... But one worry i have is how much power do I need to use this amp? How much power do you feed it with, with your signal generator? i Think my VFO can give around 8mW max.. Im going to aim for the 30m band.. not sure yet.
@@JimCoupeTQ Looking forward to your video Silvanus.
Regarding the drive required from you VFO, here is what the manual states.
RF PA mode
"The operating frequency of the power amplifier is 5MHz‐9MHz, the input power is
0dBm."
That would only be 1 mW. So your VFO should work just fine.
output filter has to be tuned to the band you use to.. Have you tried over volting it to get more output?
I agree. I followed the kit's instructions for winding the 2 toroidal output transformers and ended up with the same results (twice) for 40 meters. I have not tried raising the supply voltage beyond 13.8. I might try 15.0 as maximum. 73's
Nice simple design and interesting video series. Thanks for posting.
You are using the IRF530. Did you think about using the IRF510. That is a somewhat lighter FET and although you might think a lighter FET will run warmer, it may actually stay cooler. A lighter FET has lower capacitances and at higher frequencies gives you lower switching losses. Your output power won’t benefit much but when I see a heatsink like that with a fan for just a few watts I think there is certainly room for improvement in losses.
One other thing which comes to my mind is the output low pass filter. When it symmetrical in C and L values on input and output the impedance will be the same (50 ohm) at the antenna and FET side. The FET side has its voltage swing as dictated by the supply voltage and the 50 ohms. That gives you a certain power level.
If you make your filter asymmetrical it can offer a different input and output impedance. Say you change the filter in such a way that the FET side sees 25 ohms. With the same voltage swing you get a higher power.
You noticed that already when you played with the C values but you could use some design rules or tools and optimize this.
Thanks Robert. Great comments like this are truly appreciated!
Hi again :) what input power?
I will take a look at that Jim and let you know. Glad you got one built.