On 4/25/2017 1:05 PM, Bill Turner wrote:
> What do you call "dirty as heck"? Haven't they passed FCC acceptance?
> Is that not good enough?
The FCC has absolutely no specifications for IMD in amateur service.
Unfortunately, ARRL refuses to "call out" transceiver and amplifier
manufacturers who produce products with high levels of IMD (as well
as transmit phase noise) and have let garbage slide for 20 years or
more.
Lest there be any question, SPE's own test documents filed for approval
of the 1.3K-fx lists third order IMD much worse than -30 dB *at 800 W*.
They do not even provide IMD data for the amplifier's specified "full
power" level. The documents are still available from the FCC's server.
Of course if you insist on parking your signal right next to a 30 dB
over 9 signal, you may have a problem. The answer to that IMO is not
tighter IMD specs, but rather to QSY.
When amplifiers have 7th, 9th and higher order IMD products less than
-40 dB down - and many do (look at the test data supplied to the FCC
for approval or ARRL's product review testing) even 5 to 10 KHz away
from some of the S9+30 dB grunge buckets is not far enough.
No amplifier should be dirty enough to prevent any amateur anywhere
from working within -3 KHz/+6 KHz of a USB signal (or -6 KHz/+3 KHz
of a LSB signal) unless that signal is literally next door (within
1 km).
73,
... Joe, W4TV
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