It's been my experience (being active two weeks should make me an expert!)
that most non reactive loads for UHF are very expensive if they are
reliable. I don't see a mention of what you used for a load but many have
found similar results using their antenna as the load. However, as you are
well aware, antennas tend to be reactive in various parts of the band. This
can cause misleading results. Also, as many have said, unless it's a Bird
the indications are really only indications.
I have the RFConcepts 4-310 which does put out 110 watts with ~35 watts of
drive. However, when not using the Bird 250E slug/load and using the Diawa
and 18 el yagi, I get similar results to yours. I see the same on 2 and 6.
I expected this because the antennas have high gain which translates into
narrow bandwidth (low reactance).
That's my two cents worth! My wife can make change for you.......
At 08:15 PM 16-06-99 -0500, Jon Ogden wrote:
>
>Hi all,
>
>I have an RF Concepts 4-310 UHF brick. It's spec'd to put out 100 Watts
>with 30 Watts in. However, I get power different from that!
>
>I finally have a power meter for UHF so I decided tonight to check out my
>432 setup and see how much power I was really getting out. On 432.200, I
>found out that I was getting only about 60 Watts out of the amp with
>about 30 Watts of drive. I checked the voltages and opened the amp up.
>Voltage right at the collector choke is around 13 Volts.
>
>The I decided to tune up and down the band. My output power gradually
>increased to around 90 Watts right around 439 MHz. Then in the FM
>portion of the band it dropped down to around 80 Watts.
>
>The amp consists of two MRF648s driven in parallel. At the point where
>the input microstrip splits to go to each transistor's base, there is an
>adjustable cap. Adjusting that tunes the amp so that I can change where
>the power peaks. If I peak the power down in the small signal portion of
>the band, I can get a max of about 80 Watts. This is then the maximum I
>can get out and everywhere else on the band is either the same or lower.
>There are no other adjustments except for a couple of bias pots and the
>pot that controls the release timing of the relays. Adjusting the bias
>pots doesn't seem to do much.
>
>So I am at a loss here. Is this typical behavior for this sort of amp?
>Operating 40 Watts below its specified power in some parts of the band
>and 10 Watts below rated power in others? Or do I have a bad device??
>
>Any help would be appreciated.
>
>73,
>
>Jon
>KE9NA
>
>
>-------------------------------------
>Jon Ogden
>KE9NA
>
>http://www.qsl.net/ke9na <--- CHECK IT OUT! It's been updated!!!!!
>
>
>"A life lived in fear is a life half lived."
>
>
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>
>
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