开云体育

The IRF510 can work dependably, Allison reports years of success with HF amps at 40W push-pull,
surviving everything from accidental open antenna connections to dead shorts.
In posts to this forum from several years ago, Allison went into plenty of detail.
She even used them on 6m at several hundred watts (with bunches of them in parallel).

The QSX amp from qrp-labs uses IRF510's in push-pull, does a consistent 10W from 3 to 30mhz.
?https://www.qrp-labs.com/linear.html
Clean and linear even when operating from 12v, tolerates any antenna condition.
A product of collaboration between Hans and Allison.? ?Cost of $26 USD for the kit, a steal.
If I were building a rig like the sBitx from scratch, I would start with that amp for a PA,
perhaps add PIN diode TR switching with the HV supplied by rectified RF.
HFsignals could steal that PA design for the sBitx-v2, give Hans $5 for every unit if feeling guilty.

Using the IRF510 for RF power amps takes careful design.?
Especially heat sinking, as the IRF510 is not very good at getting heat from the die to the TO220 tab.?
The IRF510 prefers more like 24vdc for higher power and reduced distortion.
Improper design can blow the gate due to exceeding Vgs max spec momentarily
Needs more drive than an RD16HHF1 to get similar power levels due to moderately high gate capacitance.

However, Vds max is much higher for the IRF510 than it is for the RD16HHF1,
so for cases of high Vds the IRF510 would survive a high SWR better than the RD16HHF1.
Allison was of the opinion that moving to the RD16HHF1 on the uBitx would not help much.

Reading from??https://www.vu2ese.com/index.php/2022/07/20/the-sbitx-the-sdr-for-the-homebrewer/
"The power amplifier of Figure 6 is a conventional power chain, probably a little sub-optimal. Two stages of pre-driver amplification with metal 2N2222As boost the signal level from -15 dBm to a little above 100 mW"
For "sub-optimal" we could substitute "inexpensive".? One necessary change if wanting somewhat even power output all the way up to 30mhz would be an additional stage of amplification.? Gong from -15 dBm to +20 dBm (100mW) in two stages of 2N2222's is 35 dB of gain, or 17.5 dB per stage.? That's pushing it,? Though as we saw on the uBitx, optimizing a power amp is complicated, especially when doing it for a low budget product.?

If NFET's seem too hard to use and just too dang complicated, an 807 or 6146 should do fine with any SWR when operating at 40W.? ?;-)
Names could be shorter 80 years ago, they didn't have 10 gazillion different electronic parts to keep track of.

Jerry, KE7ER