what is the minumin amount of power, flex Amp

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What the least amount of power you drive into the Flex Amp and still work?
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Bill -VA3WTB

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Posted 1 year ago

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Mike - W8MM

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Power Genius XL?

The amp is linear with an FCC-limited gain of no more than15 dB.  That's 31.6 to 1, max.   Let's back away from the FCC limit to 30:1.

It follows that what ever drive amount you have will come out the other end about 15 dB, or 30 times, stronger.

Examples:

a) 50 watts drive = 1500 watts output

b) 5 watts drive = 150 watts output

c) 1 watt drive = 30 watts output

d) +7 dBm drive = +22 dBm output

One could probably use the Amp for a really high dynamic range receiver pre-amp with 15 dB gain, but it might not have a very good noise figure for 6 meter work depending on whether it uses a resistive pad to lower the gain for FCC compliance ;~}
(Edited)
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Ria - N2RJ, Elmer

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Official spec is 50 watts for 1500 out.
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Bill -VA3WTB

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Ok, so as low as 1 watt? in, and the amp will work ok?
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Tim - W4TME, Customer Experience Manager

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This isn't a common question because most people use a 100W exciter, so it is taking a little time to get the answer.
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Ria - N2RJ, Elmer

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As low as 1 watt in you'll get some amplification. You won't get 1500 watts out but you'll get something higher than 1 watt. The whole reason for this as mentioned is the FCC 15dB gain rule. Without the mandatory input attenuator LDMOS devices can produce full output with as little as 1-2w.

What are you trying to do? 
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Ken - NM9P, Elmer

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Assuming that the attenuation is in line...
50 Watts to 1500 Watts is a gain multiplier of 30.
Assuming that the amp is linear...
25 Watts in should get you 750W out.
and 1 Watt should get you 30 Watts out.

Ken - NM9P
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Mike - W8MM

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Similar to my first response of this thread.

OP needs to define terms.
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Tim - W4TME, Customer Experience Manager

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So here is the best answer I can provide at this time.  First off, Ria is correct that a small amount of exciter drive will produce a lot of power from an LDMOS type amplifier.  You can drive the amp with as little as a watt.  The amount of output is another matter altogether.

For amps sold in the US, in order to be compliant with the current FCC regulations related to the limited gain of no more than15 dB, there is a 10 dB input attenuator in the amp (50W drive = 1500W).  For the EU model, the attenuator will be bypassed, so 5 watts of drive can generate full legal limit power.
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Ria - N2RJ, Elmer

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Honestly if you can't wait for the FCC to realize it's not the 1970s anymore, you can probably buy the EU version overseas and import it yourself. That's what I did with my SPE 1.3K-FA (which I have now sold). 8 watts gave me full output. I ran it at 5 watts for about 1kw out. 
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Richard McClelland, AA5S

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Probably a more cogent point, why would anyone purchase a $7k plus amplifier to use with a $579 transceiver?  I think I'd upgrade to a Flex 6700 first and save the difference.
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Tim - W4TME, Customer Experience Manager

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Maybe.  I do not think that the spectral purity of a 1500 exciter at full power is what you want to drive any LD amp.  But certainly, you could easily have a 1000W 1500.
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VE7ATJ

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Hmmm, I don't believe Industry Canada has the same gain limitation, so what about amps sold to owners in Canada?? Most time, we get them from the US, but will there be some way to bypass the attenuator?
(Edited)
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Ria - N2RJ, Elmer

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I'm curious about that as well. I'm hoping that when the FCC rule is finally rescinded that we can remove the attenuator, or do so as an end user mod (which is perfectly legal here). I enjoy running my exciter cool. The only issue would be warranty. 
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Mike - W8MM

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It would be handy to know the original poster's definition of "work OK" or "still work".  There would seem to be an implied (but not revealed) exact question.

"What the least amount of power you drive into the Flex Amp and still work?"

"Ok, so as low as 1 watt? in, and the amp will work ok?"

My answer to both questions is another question:  What do you mean by that?
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Dale Neace

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Please reread Tim's answer he says one watt will drive it!
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Bill -VA3WTB

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I think, and I may be wrong, that there are some amps on the market that will not work well at 1 watt or below input,,this was asked to me by a friend, I didn't have the answer.
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WH6HI - Pat

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Why would you want to.....?
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AC9S

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Easy - I do this with my 6700 / 8410 to get 200 watts on 30 meters.

Keith - AC9S