Re: U3S output fets
toggle quoted messageShow quoted text
The U3A by itself doesn’t have enough drive to make more than 500 mw output from the RD15HVF1 … BUT if you drive the RD15HVF1 with one BS170 on the U3A (at about 150 mw), it should make at least 12 watts… I home brewed one (before Hans put out his kit) and mine certainly will put out that much power and more depending on the power source voltage. The nice thing about using the RD15HVF1 is that it puts out a good amount of power above 20 mhz… well into the 200 MHz range… whereas the IRF510 (depending upon the quality of the device in manufacturing) quits at about 20 mhz. But if you stay below 10 MHz, the IRF510 part is cheaper and will work fine.
You only need to use ONE part in any event!!!!!
Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ
Owner - Operator
Big Signal Ranch – K9ZC
Owner – Operator
Villa Grand Piton – J68HZ
Soufriere, St. Lucia W.I.
Rent it: www.VillaGrandPiton.com
From: QRPLabs@groups.io [mailto:QRPLabs@groups.io] On Behalf Of ian liston-smith
Sent: Saturday, February 04, 2017 9:58 AM
Subject: [QRPLabs] U3S output fets
Has anyone had any success getting about 500mW (on 40) on a U3S with a 12V supply from one (or two) RD15HVF1 devices?
I have a U3S running three BS170 fets with a PA voltage of 12V. The bias set so that without drive, total U3S current was about 50mA, and R5 adjusted until it rose to about 53mA.