Timo, It all depends on how the tri-filar is connected. It's just three parallel windings on a toroid. You could connect all three is series, tap one of the common points and get 9:1 or, you could tie

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Thx Ron, Makes sense and is what I expected. So if bifilar provides a 1:4 impedance step, what would trifilar in the same configuration provide as a impedance step? 73 Timo zr6tm

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Hi Tim. In this case it is providing a 1:4 impedance step up from the 12.5 ohm FET Drain to 50 ohms at the input of the low pass filter. Ron

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Thx Dave and Paul, Looking at the snip I agree that the bifilar winding 1 connects the 12v supply to the drain of the mosfet. Winding 1 then connects to Winding 2 to provide the PA output. Sorry for t

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I presume, because your question is not sufficiently clear, that you are talking about a push pull amplifier, where a bifilar or two winding transformer is connected between the FET Drains and the pow

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IMHO, the reason for trifilar is for tight coupling and balance between the windings. For when "close" isn't good enough! ;-) Paul On 1/29/23 22:54, timo.vandermerwe@... wrote:

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Dear all, On most class C and D amplifiers the IRF510 is followed by a trifilar or bifilar transformer toroid. Can someone please explain what the function of the this type of transformer is. (is it f

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There are people selling these as pulls on Alibaba. I have no idea why they are pulls but they are very cheap as they obviously have to be. I'll send you a PM on this. Another poss is Mini Kits in Ade

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Halden, At 50mhz I use IRF510s, a pair get me about 35W, a 4x4 push pull at 28V does a nice 200W. The idea tha the RD device at 40M is better is myth. I have a pair or irf510 at 28V that doe about 55W

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The RD15HVF1 is nice part for 144mhz otherwise no advantage and bring limits. First he specified gain of the device is not higher than IRF510 and can be lower. The power dissipation is not higher. The

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Hello Halden The 10W Linear. I don't think there is much, if any, advantage substituting a RD15HVF1. The 5W PA output power drops off quickly after 10m. The 50W Amp, I have not tested beyond 20m. The

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Hi Hans, Thanks for your comments. I'm not sure I understand your "Other than the 5W PA..." comment. If I try to use one of the QRP-Labs amplifiers with the original IRF510s on 40 MHz, which of the pr

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I get those from here. https://www.sdr-kits.net/RD15HVF1 Jim. G4EQX

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Hello Halden The idea that substituting an RD15HVF1 will automatically result in an easy improvement in performance is a bit of a myth in my opinion. Particulalry in the 10W Linear. Other than the 5W

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I wish to make an amplifier for WSPR on 8m (40 MHz). RD15HVF1s are likely to outperform IRF510s in the 5, 10, and 50W QRP-Labs amplifiers. These cost $20 each at RF Parts, and Amazon no longer offers

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Bertel your path should be okay. i suggest starting with the kit assembled without the PA, operate it QRP to see that everything is working. at this point you ONLY need a 5 volt supply - the current i

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Hi. I'm about to build the 5W HF PA to go with my U3S transmitter. I hope to be able to fit it behind everything else. I have the U3S board, a LPF relay board and a GPS board. Everything will be tucke

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Phil Tim in ZL back again. As far as the OPT is concerned , I have had a look at optimising it at 80 Mhz as a half way house between 6m and 2m. Type 43 material as per previous is death to RF at such

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Phil for the RD15HVf1 you will have to "twist the pins" on G and S it is I believe . People who have made PCB drafting errors of this type have reported losses at HF NOT VHF of 0.3 dB from this. Error

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IRF510 will work at 6m, but not at 2m. For 2M you need the RD15VHF1. Allison ------------------------------- Please reply on list so we can share. No private email, it goes to a bit bucket due address

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