This is the first one of these transmitters that I have installed. This particular unit is analog only, but there is lots of room left over for an HD exciter if need be.
The size of a 10 KW FM transmitter these days is pretty small, basically taking up the equivalent of one rack. This is a relatively small transmitter room, the old tube transmitter basically took up the entire room. With this unit, there is room to install a full power spare, if that was desired.
RF modules use LDMOSFET devices, each module has a power output of approximately 1,600 watts.
There are eight power amp modules and seven switching power supplies.
One issue at this site, there is no reliable three-phase power available. There was a three-phase open delta, but man, that thing scares me a little bit. Since this is a single-phase setup, I was curious to know what the current draw on each leg was at full power. I measured with my clamp-on ammeter; 54.3 Amps at 120 volts, or 6516 watts per leg. Overall power draws 13,032 making the AC to RF efficiency 65.2%. VSWR calculates out to 1.21, which is not great. I think the antenna could use a little bit of tuning love.
We have few of those transmitter up here in Quebec, and they are working great, nice product, easy to operate, seems reliable. Well, will see in the future.
Regards
Smart move, avoiding that open delta. They’ll run industrial motors OK but can be murder on solid state devices. Harris products used to have warranty issues on open delta supplies, I don’t know if they still do.
Open-Delta is a transmitter killer. We recently ordered a BE AM-6 transmitter will 220 VAC single phase power rather than deal with the 3 phase open-delta at our site. Local Electric Supplier wanted $15K to close the delta… we passed on that idea.
Wow, that 77w reflected surprised me, all right. Agree, antenna could use just
a bit of TLC…
Keep up the good work! 73 Don K4ZA
Installed a Fax-20 four years ago just runs and runs
have never had a problem. Running it at 16.5kw.
I have a FAX20 running in IBOC only mode, on air for 3-4 years now….It runs.
I put a FAX40 on air almost one year ago, running 24kW analog -14dbc IBOC. Likewise—It runs. It got confused during a thunderstorm last spring, but came back up making 2600 watts. I feared the worse when I saw nearly every PA module “red” inside. But it only wanted a reset, and away it went.
Just be sure you have enough HVAC if you lose a power block in the FAX 20 or higher…they will dump a bunch of hot air in the room! (Hot air is not format dependent…..)
We have two FAX40’s and a FAX30 here in Tampa. The FAX40’s are both running -14db HD common amplification. 35kw FM plus 1.4kw HD. 48 years in the business and these are the best transmitters I’ve ever laid hand on. Very simple and Very reliable.
Just installed a Fax 5 last week for Yale university running a 4.1K analog only so far problems
Sounds great.
I should have said running at 4.1kw analog only
with no problems.