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Old October 31st 05, 11:09 PM
Lazy Senior
 
Posts: n/a
Default Old Xmtrs, "Ancient Modulation" and Amps

Edward Knobloch wrote:
Hi,

No real pitfall with a modern amp, as long as you get one
rated for continuous duty a.m. operation.
You need tubes with a lot of plate dissipation rating,
since a.m. linear is inefficent, maybe 25% carrier efficiency.
Look for a linear with ceramic tubes, a big blower
and a heavy-duty power supply.

You may need an rf power attenuator between the Ranger
and the linear. Most modern linear amps
produce 1500W peak output with only about 65w peak drive.
Your Ranger will produce 160W pep output in a.m. mode
(at 40W carrier). The linear will be producing 375W carrier,
at legal limit, so it will be almost 10dB more output
than the barefoot Ranger. With no modulation,
the linear's power input will be about 1,500 Watts
(assuming 25% efficiency).
A lot of heat will be dissipted from the linear's plates,
about 1,125 Watts.

A T-network made of 3 each 100W lightbulbs may be an OK
rf attenuator at the linear's input, so you don't overdrive it.

73,
Ed Knobloch

Ed
Thanx - this is one of the most usefull replys I have gotten on this
subject.

Lazy Senior