We’re running a couple GatesAir FAX 3K, 3KW transmitters, one at only 1250 watts, and one at 1950 watts. The PA efficiency at full 3KW is a bit over 70 percent, but at 1250 watts is only 50 percent. At 1950 watts the PA efficiency is 63 percent. I haven’t seen any charts, but these are my real measured values, Output Power/PA Volts X Amps. Have been able to improve the lower power efficiency a bit by reducing the adjustable supply voltage, and doing a re-bias procedure.
From: Kevin Kidd [mailto:email@example.com]
Sent: Wednesday, May 09, 2018 10:52 AM
Subject: Re: [CRTech] Can you run a Nautel Xmtr at 110%?
Just curious, is there a chart or curve available to check out for the various products efficiency vs tpo and the max recommended power? Most of my client's Nautel TX's are running close to nameplate power but some aren't.
On Wed, May 9, 2018 at 12:00 PM, Gary Liebisch <firstname.lastname@example.org> wrote:
We get that question all the time and you can certainly run it at 110%. In the days before software was used to limit power, it was common for folks to use all kinds of modifications and tricks to "juice up" tube transmitters beyond their rated power. But now software is the gate keeper on excess dissipation, and our components are conservatively rated. You get best efficiency on a solid state transmitter when it is run at rated power or above. If your licensed TPO is 5500 w and you follow the advice of buying the next larger transmitter (a 7.5) then you are taking a double hit on efficiency, not running it near rated power, not to mention that a 7.5 is really a 10 internally anyway, so you're only at about 50%. We may not talk you out of doing that, though, because it puts more commission in our pockets! :)