Just what the world needs...another dirty 13.8v...oops 12vdc mobile
amp.
They don't need to be dirty ... the problem is that it takes so many
"pills" to make the power that designers tend to use the 60, 80 or
100W rated transistors right up to their saturated output rather than
limit each pair of devices to 50 - 60% of PEP output. For example ...
the MRF-421 is rated as a 100W transistor but third order IMD is
minimized around 50-55W. An "eight pill" design could make 900W in
saturated mode but in order to keep it clean, the output would need to
kept to 500 W PEP. This, in spite of the fact than Communications
Concepts sells a 2 x MRF-421 board set as a "180 Watt HF amplifier"
(Motorola AN-762).
73,
... Joe, W4TV
On 2014-12-13 10:29 AM, Gary Gregory wrote:
Gee whizz
Just what the world needs...another dirty 13.8v...oops 12vdc mobile amp.
Why do folks need to run so much power mobile?...oh yeah, i forgot....silly
me.
Gary
Vk1ZZ
K3, KX3, KPA500-FT, KAT500-FT,P3.
On 14/12/2014 1:02 AM, "Joe Subich, W4TV" <[email protected]> wrote:
On 2014-12-13 9:31 AM, Dan Baker wrote:
My feature request is for a 500 W mobile version of the KPA500.
That's difficult due to the 12V requirement. To do it right using 12V
capable transistors/FETS would take at least two and probably four
amplifier boards similar to the KPA500 with associated splitters and
combiners. *Without tuner and power supply* would put the price
somewhere north of the KPA-500 just because of all the controls, heat
sinks, etc. There is a reason that 12V capable transceivers do not
run more than 100W output (typically 2 x 60W or 2 x 80W transistors
in push-pull).
73,
... Joe, W4TV
On 2014-12-13 9:31 AM, Dan Baker wrote:
My feature request is for a 500 W mobile version of the KPA500. I think
the Mississippi company is the only one making a 500 watt mobile amp now.
Seems like there is an opportunity to be had. I would gladly donate my
ALS-500 to Wayne and Eric so they could see how not to build one.
Dan KM6CQ
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