Hi Richard,
I don't have anything to do with broadcasting, but when I first ran across
their DX line of AM transmitters, it really blew my mind. It seems though,
that it is really hard to find detailed info on them. Do you have a link
that describes what happens in some detail. The best I have been able to
come up with was anecdotal data let to from the WLW web site. There must be
some article that was published in some trade magazine. My questions a

The 50 KW transmitter supposedly has 60 some modules of about 1KW each. How
does this jive with being able to get the 200KW PEP that is required for
100% upward modulation? Does the combiner add voltage or power? Seems like
it would be voltage, but then the impedance a module sees would depend on
how many are active at a given time.

What is the digital sampling rate? Seems to me they need a high power
bandpass filter to get rid of the sampling frequency after the combiner.

BTW, I think a lot of people are going to confuse this with Digital AM.

Tam/WB2TT

"Richard Fry" wrote in message
...
"Richard Clark" wrote about the specs for Harris Broadcast Txs:
As for the specification for output impedance gone missing :-)
MW-10B SPECIFICATIONS
RF OUTPUT IMPEDANCE: 50 ohms, unbalanced.
Other output impedances available on special order.
Harris Platinum Z FM transmitter
100 ohm output impedance (unbalanced)
HARRIS SW-50 A
RF Output Impedance 300 ohms balanced, 2.0 to 1 maximum VSWR
Well, instead of reciting their complete catalogue, it is easier to
simply say I could not find any product that did not specify an output
impedance, much less that others were available on special order.
_____________

I won't try to soften this: your conclusion above doesn't just _appear_ to
be wrong, it IS wrong. 100% wrong. The impedance published by Harris is
the
expected load impedance, not the tx source impedance -- which is the
convention used by all OEMs of broadcast txs (at least).

How do I know? I was the author of all of the brochures and technical
data
sheets for Harris' entire FM product line for the ten years before I
retired. That any published value of impedance applied to the load
impedance expected was/is universal across the product lines: AM/FM/TV.

Your post above showing 100 ohms for a Platinum Z FM tx also is wrong. It
is designed for a 50 ohm load. Here is a link to an on-line brochure for
the current 10kW model:
http://www.broadcast.harris.com/prod.../HAR173569.pdf
Observe the statement at the bottom of the right column on the last page
thereof, which I quote below for your convenience:

"All specifications referenced to any single output frequency
(87.5-108MHz),
nominal rated output power, and 50 ohm, isolated, non-reactive
load."

No other RF impedance spec is given in the very detailed list of specs
contained in these brochures.

Kindly recant your accusations.

RF