[SBE] Harris HT40 TV transmitter question

[Jon Frank]

We had a 33Kw low band Harris Platinum and we did run in to that problem if we had to take a module out for service.   The PA fault light is turned on due to the lack of a jumper that connects two pins through the module mating plug. When a module is plugged in to a transmitter chassis slot, the jumper completes a circuit that tells the logic that the module is properly seated.

In our case we had talked to Mike Finley (The Platinum guru) and suggested an idea for a dummy module that we could install in the place of a module we had removed.  He had it built and sold it to us for very low money.  The module had a jumper on the mating plug and also served the purpose of filling the hole so that the proper air flow was maintained around the other modules. I believe Mike may have retired at the end of NTSC and I'm not sure Harris makes these available, but you could ask.  You could try just buying the mating plugs and soldering a jumper wire on.

Another idea would be to modify the old aural modules by simply opening the dc power connections inside of the modules,  then installing those modules back in to their old slots.

Jon Frank
WGBH
Boston
________________________________
From: sbe-bounces at sbe.org [sbe-bounces at sbe.org] On Behalf Of Curt Yengst [cyengst at star991fm.com]
Sent: Tuesday, June 22, 2010 4:20 PM
To: sbe at sbe.org
Subject: [SBE] Harris HT40 TV transmitter question


I'm not a TV engineer, nor do I play one on TV; but I'm currently assisting at a local TV station.  We've installed a Harris HT40 which was purchased second-hand.  Everything works great except for one thing.....

We're not using the stock exciters, nor are we using the aural modules in the PA cabinets.  Since the station is digital, we're using an after-market digital exciter and using the visual PA's to amplify that signal.  We've disconnected the aural modules from the power supplies, and the stock exciters are completely removed.

We now get, as can be expected, module fault alarms and exciter alarms on the display in the control cabinet.  The exciter alarms are not the big issue here, but the module alarms are.  We know the alarms are caused by the fact that the aural modules are disconnected.  The problem comes if and when we have a legitimate visual module fault.  There's no way to tell.  This prevents us from connecting the module fault alarm to our Burk remote system.

Has anyone else been through this configuration already, and could you suggest a way to "fool" the transmitter into seeing good aural modules, or even getting it to just ignore the disconnected modules?

Curt
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