Ideas for "reach"....

[AKLes]

Station for which I do volunteer engineering has, for years, used CRL MBL-100 limiters (more about the plural in a moment). The idea is to hold the bandwidth down to around 4 kHz and push hell out of the signal. Audience is mostly 75 miles or more beyond the 25-kW single tower, folded unipole, transmitter site (AM). Audio quality is a remote secondary consideration to "reach" 'cause most folks listening are using cheap plastic radios.

The CRL's work really well. Thing is, the power supplies in 'em are trouble; life expectancy of 1-4 years. Hence there are two CRL's in parallel with only one having power at any given time. Always kept a spare power supply on hand so that when one failed at 3am during a blizzard I could just use the remote to switch over and then swap the supply when convenient. Now there are no more power supplies available and these are not repairable by any normal means. CRL is trying to find a vendor for a direct replacement but with no luck so far.

So....

Someone has suggested an Omnia as a direct replacement. It seems like overkill for the purpose and I haven't been able to determine if it has the ability to restrict the BW as much as we like. Of course wider bandwidth would be OK but only if it didn't also restrict "reach". The important thing is maximum signal at the greatest distances because these are places with no other signals available and highly dependent on the station for weather, news, generally keeping in touch with 'civilization', such as it is.

Frank, are you out there?

Ideas?

 

[littlejohn]

Surely the voltages and required currents are known? Build a 'brute force' supply, and go about your business. You ought to be able to gin one up with a multi voltage transformer, or a center tapped one, and a handful of three terminal regulators and a buncha caps. Put a multiconductor plug on the box, and outboard the power supply.
I subscribe to, if the box I got is doing the job, why look for another.

 

[mr_elbows]

Got any info on the PS ?

It can't be THAT complex.

Gary

 

[AKLes]

Replying to Gary first....

The bad power supply was dumped when the good spare was put into service so I don't have any info on it at hand. The CRL units are over 1,000 miles from here but I would imagine I could have somebody fax over the manual or parts of it. More below:

Surely the voltages and required currents are known? Build a 'brute force' supply, and go about your business. You ought to be able to gin one up with a multi voltage transformer, or a center tapped one, and a handful of three terminal regulators and a buncha caps. Put a multiconductor plug on the box, and outboard the power supply.
I subscribe to, if the box I got is doing the job, why look for another.

I'm hoping to not have anything "hanging off" the units and am not in a rush to get a replacement 'cause there are two working units there right now. If, after a reasonable time, CRL doesn't come up with one that'll fit inside the box I may have to go that route. It's what I'm trying to avoid.

The idea of the Omnia was suggested to the manager of the station by the manager of another station who is using one but is non-technical. He makes some nice claims about the Omnia so the question arises of whether it's worth the effort and cost to change over. Unless there is some compelling reason to go to the Omnia I agree that keeping the CRL boxes running is the best way and, if I have to, I'll build something.

Getting too old and lazy to be fabricating/modifying stuff if I can get a replacement that fits as intended.

Thanks for the thoughts!

 

[Sgeirk]

I was on a budget, used a CRL amigo and a vintage Audimax...whoo hoo that 1kw BE solid state xmtr sound niiiiice. Not the best I've ever heard, but for what was spent? No brainer.

Reasonably loud, very listenable, good coverage, and dirt stinkin' cheap.

CRL's AM stuff rocks, in my book.