>> A well designed amplifier using 8 VRF-2933 or a pair of the Motorola/
>> Phillips 1200W TV transmitter "bricks" could be done commercially at
>
> I don't want a 1200 watt amp that has to be derated for digital.
8 x VRF-2933 or 2 x 1200 W Motorola/Phillips "blocks" are not a 1200W
amplifier. 2 x VRF-2933 do 600W brick on the key in the KPA-500. Both
configurations I listed will do 2 KW CCS with reserve gain given the
proper cooling system design.
> FCC rules mean I have to import a 2KW nominal, 2.5KW PEP amp to have
> an amp that will run the legal limit any mode key down.
Yes, and by law US Customs should impound your amplifier until you can
provide the FCC approval documents for it (it does not fall under the
"one off" exemption since it is a commercial product). Fortunately,
Customs is not designed to look for individuals importing their own
amplifier.
> I can currently go from a 1.1:1 to a 1.3:1 and see no difference in
> output. I could not do that even at 1.2:1 with the SS amp.
Then the amplifier in question was not particularly well designed.
A properly designed solid state amplifier should be able to handle
a modest amount of QSY ... the KPA-500 generally shrugs off anything
under 1.5:1 (or more).
73,
... Joe, W4TV
On 4/29/2012 9:04 PM, Roger (K8RI) wrote:
>
> On 4/29/2012 8:43 PM, Joe Subich, W4TV wrote:
>>> Yes, I prefer SS over tubes *but* I want one that is capable of at
>>> least 2 KW nominal CCS or 2.5KW PEP to run the legal limit on any
>>> mode contest style. To me that would be a valid comparison.
>> No, that's an apples to oranges comparison since you want a solid
>> state amplifier to be capable of 65% "headroom".
> No, it's exactly what I expect out of a tube amp, and I have one that
> will do it. So it's a valid comparison if I want the same thing out of SS.
>>
>> A well designed amplifier using 8 VRF-2933 or a pair of the Motorola/
>> Phillips 1200W TV transmitter "bricks" could be done commercially at
>
> I don't want a 1200 watt amp that has to be derated for digital.
>
>> a price that is competitive with the top of the line Alpha but FCC
>> rules make it very impractical for any US manufacturer to bother to
>> do so.
>
> FCC rules mean I have to import a 2KW nominal, 2.5KW PEP amp to have an
> amp that will run the legal limit any mode key down.
>
>>> BTW I had ah HL1.5KFX for a few months and nary a complaint, *except*
>>> It needed a very low SWR to let it output full power. I replaced it
>>> with a manual tune, amp that will run 2 KW nominal and so far am very
>>> happy with it.
>> Again, apples to oranges ... you would never run your manually tuned
>> amplifier into a high SWR without tuning it for that SWR. Why would
>> you expect an untuned solid state amplifier to handle a high SWR
>> without adding a tuner (either manual or automatic)?
>
> Please note, I said, very low SWR. I can move roughly 70 KHz on 40
> without having to touch the amp or line tuner.
> With the HL1.5KFX I'd have to retune. I can currently go from a 1.1:1 to
> a 1.3:1 and see no difference in output.
> I could not do that even at 1.2:1 with the SS amp.
>
> 73
>
> Roger (K8RI)
>
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