On 05/11/2018 08:20 PM, RADIO DOCTOR wrote:
What remote control switches are being used for AM nowadays? Shielded
for coax or open relay(s) on a panel/board? Controllers? Automatic?
Kintronic's RF contactors have been the standard for years, both at the
ATU/LTU and in phasors, and you've already gotten a pointer to those.
Kintronics has a wide variety of controllers and can custom build pretty
much anything related to AM antenna systems, including dummy loads.
The transmission line is a 1/2" late 1980's version of the current
1/2" CableWave (RFS) LCF12-50J.
1/2 inch at 5kW? Well, CableWave does rate the 2013 version of this
cable for 38kW average at 1MHz and 38kW peak; with AM you have to take
into account the peak, not average, power, which for 5kW at 100%
positive modulation is 20kW (peak voltage at 100% 1kV; the cable is
rated 1.95kV) . Should be ok, although I have always recommended 7/8's
for 5 and 10kW.
What's best for jumpers? Should I bother with connectors or just wire
it up? Transmitter will probably be 7/8" EIA output, but DIN
connectors might be nice for hooking everything together. Is there a
7/8" EIA to appropriate size DIN adapter. I've never used DIN
At 5kW I'd use 7/8's flanges everywhere. They're easy enough to work
with, and it's just a few bolts to decouple when you need to do so. In
this case it's not the voltage but the current that becomes the primary
concernt; your connector needs to handle 10 amps with dead carrier and
20 amps at 100% modulation (and 1kV at 100% positive peaks). This is
hard to do with connectors smaller than 7/8's flanges, although the 7/16
DIN is a really good and rugged connector.
Being an FM Guy, I've rarely dealt with real AM. Always tried to keep
AM at least 50 dB down :)
AM is a completely different beast in many ways. You're solidly down in
lumped constant territory, but distributed constant stuff keeps showing
up..... AM directionals are my favorite; love negative resistance
towers..... :-) You're also into real loudness-war territory, since
with an AM your effective maximum listenable distance is directly
related to positive modulation percentage.