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FM Exciters

S

speakerman

I know this topic can be answered in many ways including objective and subjective however I am interested in a general consensus as to which FM exciter does not color the sound. This should be very difficult to determine since there are so many different receiver designs out their. The transfer function has to be different if one were to compare all detector vs modulator designs. I'm looking for a common denominator (if it exists).

We know bass is better with dual-loop phase lock loop modulators due to the lower pole of the 2nd lock. What about the pure digital exciters? The specs look great however are their dynamic distortions (similar to SID and TIM) that may make some exciter sound worse than others?

I'm an analog guy that still feels analog can be as good or better than digital in some cases. Digital processors have done a great job of constraining the dynamic range of the program material...does the exciter also make a difference in the perceived sound by the listener?
 
The Continental 820D and D1 are about as clean and quiet as it gets. The FX 60 series BE is also. I've not played with the Nautel produict, but it gets good comments from folks whose opinions I trust.
Ogonowski modified some BE FX30 boxes to the point they sounded excellent, but the mod slowed the AFC loop down to the point it took forever to lock. We ran ours on a UPS to overcome this. If he still offers that service, it would be a very cost effective way to get really nice spund.
 
I've been working on an upgrade for a local LPFM. The plan is to go completely digital (they actually have a budget). We are upgrading to digital consoles and Omnia processing. The problem that I am finding is that there are only a few exciters/transmitters that are LPFM certified. I'm in search of an LPFM transmitter/exciter which is transparent as possible. I've compared Bext against BW and the BW (to my ears) won. I really don't need the built in processing/stereo generator in the BW.

In the spirit of this thread, I'm also in search of the best sounding exciter that is certified for LPFM in accordance with Section 73.1660(a)(2)
 
My guess is BW would be the winner for your LPFM. It's too bad the FCC in their infinite stupidity came up with such a strict certification rule for LPFM while the rest of us just have to use stuff that's compliant. It makes no sense at all... (sort of like their new "Broadband Plan"!) RF is RF, unless the FCC bureaucrats are involved.
 
In case it's not clear or apparent - BW Broadcast transmitters are FCC certified for LPFM.

I'm looking forward to seeing some of you at NAB. We are at booth C3034. Our customers are also welcome to attend our cocktail party. www.bwbroadcast.com/nabparty

Regards
Scott
 
I am using a Norcom exciter on WLRE which is an LPFM. Norcom was produced by Leo Ashcraft and was LPFM certified. I tried three different exciters and the Norcom along with my Orban 8100a had the best sound. The Nicom exciters are basicly the same make as Norcom and are still being produced.
 
I've heard some horror stories about some of the more modern Nicom exciter stuff. I have one of their amps that seems to work perfectly OK, but I'd be pretty leery of their exciters based on word-of-mouth from others...
 
For about what something like the Nicom would cost you can get a good used BE FX-50, or, with some looking around, a Continental 802B.

On one station I have an FX-50 paired with a Nautel transmitter. Just inherited a site with an ECO-4 and an Energy-Onix (e.g.--an RVR) exciter. A rebuilt 802B is going in there shortly, with an 802A as a back-up.
 
Looking for my first exciter ever. Want it to be LPFM compliant. Already have a 250 watt transmitter donated. The donor will send it, just before I sign on. (That's his stipulation) (Gotta be 99.9% built before I can claim this gift) Once I get the exciter, then I can start building out my new LPFM radio station and get the transmitter. If you or know of anyone that has one they want to get rid of or donate, let me know. This is Dan from WPJB-LP Selma Alabama and I approve this message.

Dan <><
 
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Beyond coloring the audio; I'd stay away from BE FX-30 and Continental 802 (A or B) exciters. Their filters are pretty bad and the Continental 802's in particular, have poor signal to noise and prone to micro-phonics.
 
You should make sure the "transmitter" you are getting does not already have an exciter built-in. If it does, you'll need to spend money on an audio processor, not an exciter.
 
I assume you know how much power out of the transmitter is required to make the licensed ERP. The next question would be how much power from the exciter is required to make the transmitter output requirement. You don't want to overdrive the transmitter - that could be an expensive scenario.
 
You also want to make sure the exciter and transmitter are accepted for LPFM use, so your likely looking for a new exciter as your primary. You can use a non LPFM certified transmitter as a backup though.
 
I'm making sure the exciter is compliant with the LPFM set up. I think I've found one. Will keep you posted and let you know how things turn out on it.

Dan <><
 
Here's some more info on the transmitter, that's been donated to me.

Dan <><

This is Bext/ RVR RF amplifier, 250 watt, solid state. Any 20-30 watt exciter will work, if it meets FCC specs...and must accept composite stereo or have stereo audio inputs if you want to
broadcast in stereo.
 
Just found an Exciter for the radio station. Mr. Leo Ashcraft's LPFM store is where I'm getting it from. Once I get it, then we can start building. Hope to be on by Mid January 2017.

Dan <><
 
R.D.P. said:
Just found an Exciter for the radio station. Mr. Leo Ashcraft's LPFM store is where I'm getting it from. Once I get it, then we can start building. Hope to be on by Mid January 2017.

Dan <><
Click to expand...

I could be incorrect, but my understanding is that every part of the RF chain has to be type certified for LPFM use. So a type certified exciter married to a type verified amplifier (and vice-versa) would not be legal. Meeting FCC specifications is different than being certified. Type Verified is not the same as Type Certified. There are also older standards, now obsolete, called "Type Approved" and "Type Accepted" floating around. Most modern broadcast equipment is "type verified". Type verified equipment has been tested by the manufacturer or an independent testing lab and found to be compliant with the FCC's emissions standards. Type Certified equipment has gone through the same process, but the testing data has been submitted to the FCC, or an FCC approved lab. The FCC has then issued a certification number that must be permanently affixed to the equipment. So, equipment that works perfectly and passes all emissions tests, but has not been "type certified" is still not legal to use. In one case, a manufacturer started out making "type verified" equipment and later got that same model "type certified". Units made before they were certified are illegal to use in the LPFM service, even though nothing changed except the labelling.

Also, it is true that the FCC rules appear to allow emergency transmitters in any service to be non-certified, provided that they are not used more than 720 hours in a year (30 continuous days). However, an LPFM station in Florida got into big trouble and drew an initial $12,000 fine (later reduced) when their main transmitter failed and they borrowed non-certified equipment as a backup. Unfortunately for them, there was a spur in the aircraft band that interfered with an air dispatch channel. There was a bit more to the story, but the owner told me that his station got a visit from the FCC, US Marshalls, Dept of Homeland Security, local sheriff, and FAA all at the same time. Pretty scarey stuff.

A summary can be found at:
http://www.radioworld.com/article/lpfm-fine-reduced-in-faa-interference-case/211392
 
Kmagrill said:
I could be incorrect, but my understanding is that every part of the RF chain has to be type certified for LPFM use. So a type certified exciter married to a type verified amplifier (and vice-versa) would not be legal. Meeting FCC specifications is different than being certified. Type Verified is not the same as Type Certified. There are also older standards, now obsolete, called "Type Approved" and "Type Accepted" floating around. Most modern broadcast equipment is "type verified". Type verified equipment has been tested by the manufacturer or an independent testing lab and found to be compliant with the FCC's emissions standards. Type Certified equipment has gone through the same process, but the testing data has been submitted to the FCC, or an FCC approved lab. The FCC has then issued a certification number that must be permanently affixed to the equipment. So, equipment that works perfectly and passes all emissions tests, but has not been "type certified" is still not legal to use. In one case, a manufacturer started out making "type verified" equipment and later got that same model "type certified". Units made before they were certified are illegal to use in the LPFM service, even though nothing changed except the labelling.

Also, it is true that the FCC rules appear to allow emergency transmitters in any service to be non-certified, provided that they are not used more than 720 hours in a year (30 continuous days). However, an LPFM station in Florida got into big trouble and drew an initial $12,000 fine (later reduced) when their main transmitter failed and they borrowed non-certified equipment as a backup. Unfortunately for them, there was a spur in the aircraft band that interfered with an air dispatch channel. There was a bit more to the story, but the owner told me that his station got a visit from the FCC, US Marshalls, Dept of Homeland Security, local sheriff, and FAA all at the same time. Pretty scarey stuff.

A summary can be found at:
http://www.radioworld.com/article/lpfm-fine-reduced-in-faa-interference-case/211392
Click to expand...

Was not aware of the rule that allows a non cert transmitter for emergency use. Have a be-fx 50 and a Tepco 250 transmitter that are not certified and have wondered how safe it would be to temporarily use them if needed. Where is the rule you are referring to?
 
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