Handling tube with handles....

[W7TFO]

Here area couple shots of my endeavors last night.  I know, it isn't AM.  At least not much AM by plan.   

The old girl is a Harris HT-35 in HD analog service at KJZZ in Phoenix.  About 34K TPO, somewhat less as this is high-level combined hybrid digital into a 12-bay ERI antenna.  I didn't show the digital side.

The last photo is a triple bandpass cavity on 91.5 mHz used on site.

More to come.

[N3DRB The Derb]

"old girl"  how old actually? late 80's (guess)

[W7TFO]

The Harris is relatively new, I installed it in July '08.

[ke7trp]

Nice Dennis.  Any chance I can get a Tour sometime?  I would love to check out the station in person sometime. 

Did the old tube die?

C

[Bill, KD0HG]

The Harris HT-35 FM XMTR is a hell of a terrific box.

I bought one 10 years ago and never regretted it. 575 watts of drive and 32 KW out- Piece of cake. That 4CX20,000D is one heck of a jug.

The HT-35 is a derivative of the Harris low band analog TV transmitters.

I get around 18 months out of a PA tube at 8,300' elevation...
the air blower is lacking when the air is thin.

There's a pair of Harris
HT-30s on Squaw Mountain, west of Denver, at around 12,500' . Owned by KXPK-FM. Squaw is sometimes impossible to get to in the winter..
a snow cat is advised. So they've got a pair of 30s combined, where they only need 30 KW TPO. If one craps out, they're still up to full power.

That's the only site I've been up to where there's Oxygen masks and tanks. You get really whacky working on Squaw Mountain unless you've got 20 year old lungs. In the summer, you will enjoy the lightning up there..

The radio site is the stone residence of a 1940s-1950s Forest Service firespotter there in Roosevelt National Forest.  He happened to be a ham.

Eventually, some people bought his place and turned it into a broadcast -communications site. Denver's KXPK and KYGO moved there, Each are 100 KW ERP from 12,000+ feet.

The elevation and power for those Class C FMs  hardly seems fair. You can get both of those stations 300 miles out of Denver.

[W7TFO]

Anytime one of you is in town, look me up and get a tour of the crazy transmitter site that is South Mountain.  In the most competitive market in the US, with over 40 carriers (AM, FM, TV) for a metro of 4 million. 

South Mountain has over 280 users at the present time, I wouldn't want the job of plotting a 3rd-order intermod chart.

The original Eimac tube got only some 8500 hours on it before death, we'll see what the new Econco rebuild does.  I suspect it will run twice as long.

Here is a shot of the mains ammeter.  It runs that, 24/7/365, on all three legs @ 480 Volts.  Glad I'm not paying for it....

[N3DRB The Derb]

damn, I've never seen a power draw like that. 

[KB3RRX]

hate to see a short in something with that kind of draw
Cool pics though thanks for posting em
bet it keeps things warm

Wayne
KB3RRX

[W2PFY]

The original Eimac tube got only some 8500 hours on it before death

There are 8760 hours in one year. Do they run that thing at full bore? What would be a reasonable normal life span for a tube like that? I know of a FM station in Maine that uses a 4CX300 as a driver and it will only do one year before it starts dropping off in power. The 4CX10000D final lasts a few years.  I know another owner in the Syracuse are that has been using Chinese 4CX15000 tubes in FM service and he says he having very good luck with them.