BE AM 6A Mod

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BE AM 6A Mod

Postby NE8E » Fri Sep 21, 2012 12:50 pm

This could apply to the AM 500A, AM 1A, AM 6A, AM 10A, AM 2.5E, and AM 5E.

Four month’s ago, when our BE AM 6A lost power to Module 2, a quick call to BE indicated the probable cause was a pair of capacitors on the modulator board. Great! They knew what was wrong. The cost for replacement... $80 each! Yikes! Well, we bit the bullet and shelled out the $160 plus shipping. Sure enough, this fixed the problem.

Last week, just 4 monthes later, Module 4 went out. So, another call to BE. This time, they informed me there is a known problem with the caps, and they have a fix. A kit to replace the capacitors. The kit costs $120 per module! Yikes again! That's $720 for the BE AM 6A. That would be $1200 if we had the 10A!

2012-09-20_15-59-22_555 (800x450).jpg


It was time to do some research. The picture of BE's kit showed a tiny pair of circuit boards you attach to the Modulator board, with 2 smaller caps. My guess is they went with a pair of 150uF instead of the larger 330uF. Either way, that seemed like a lot of money for a little board and a couple capacitors. It also looked like those caps are going to be even harder to replace when they go bad in a few years.

According to Cornell Dubilier, the original capacitors are the wide-temperature, high ripple current capacitors for power-supply outputs and UPS battery stiffening. The 3rd lead on those caps have no connection to the circuit. I suspect they are just for better strength to survive shipping abuse. I like the idea, but our transmitter is going to be here until the day it dies. We don't need that third lead anymore.

I combed the big distributors web sites looking for replacements. I wanted HIGH temperature, Long life, high ripple current capacitors, with a diameter no larger than 20mm but preferably 18mm, they must be commonly stocked and IN STOCK. I found exactly what I needed in the Panasonic EEU-ED2D331 from Mouser. Now, I wanted a fast way to replace these in the future, yet I wanted them to be held securely. I went with #1731022 Phoenix terminal blocks with top screws and side connections and 7.5mm spacing to fit the original board holes. I marked the positive with a red sharpie. I couldn't find my black sharpie. :x

2012-09-20_17-08-44_607 (800x450).jpg
2012-09-20_16-28-15_438 (800x450).jpg


Everything fit together beautifully. I was going to use zip tie mounts for added security, but I was not sure the zip ties and the foam tape would stand up to the high temperature for the many years of service we were expecting from the BE. I thought RTV162 was a better choice. It is made specifically for bonding electronic components to substrate. It also comes off nicely if you need it to.

2012-09-20_16-38-13_495 (800x450).jpg


So, here's the rundown:

Original caps: $160.00
BE Fix Kit: $120.00
My Caps & Blocks: $11.06
Savings doing entire transmitter: $893.64
Green lights and smiling owner: Priceless

2012-09-20_22-40-01_550 (800x450).jpg


Here are the parts needed:
http://www.mouser.com/Search/ProductDetail.aspx?R=1731022virtualkey65100000virtualkey651-1731022
http://www.mouser.com/Search/ProductDetail.aspx?R=EEU-ED2D331virtualkey66720000virtualkey667-EEU-ED2D331
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Re: BE AM 6A Mod

Postby BroadcastDoc » Fri Sep 21, 2012 3:40 pm

Outstanding! Thanks for sharing.
Christopher "Doc" Tarr CSRE, CBNE, DRB
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Re: BE AM 6A Mod

Postby NE8E » Fri Sep 21, 2012 7:08 pm

BroadcastDoc wrote:Outstanding! Thanks for sharing.


Thank You! I hoped some others might have other ideas to share, or maybe faced this same problem. I would love to hear how others solved it.
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Re: BE AM 6A Mod

Postby davek » Sat Sep 22, 2012 7:19 pm

Now to figure out how to pocket some of those savings for yourself maybe? :)
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Re: BE AM 6A Mod

Postby BingNYEng » Sun Sep 23, 2012 5:30 am

How old is the transmitter in question? I have 2 of these in service. One was installed in 99, the other in 02.
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Re: BE AM 6A Mod

Postby amradiofan » Sun Sep 23, 2012 8:23 am

This transmitter was new to the station in July of 2005. Aside from these caps now going bad
on (2) separate modules, wouldn't trade this box for any other one! Very stable and reliable!
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Re: BE AM 6A Mod

Postby NE8E » Sun Sep 23, 2012 2:29 pm

davek wrote:Now to figure out how to pocket some of those savings for yourself maybe? :)


It earned me a couple of dinners at my favorite restaurant for my wife and I. This was far more than I needed. The owner takes very good care of me.

My Digital Electronics instructor passed on some great wisdom that I chose to follow. He said "You can do a job you love and take what ever money they give you, or you can put the cream between the cookies (as he motions pulling a lever up and down) and get the big bucks. I know a factory job would kill me. I NEED to be able to think. I chose to do a job I love, and what ever money I get is just a bonus. :D
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Re: BE AM 6A Mod

Postby NE8E » Sun Sep 23, 2012 2:44 pm

BingNYEng wrote:How old is the transmitter in question? I have 2 of these in service. One was installed in 99, the other in 02.


According to BE, boards shipped after July 28, 2010 have been fixed. Boards previous to this have the issue. I hope this helps. You can always pick up the parts and have them on hand for when they go bad. Just a thought. :)
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Re: BE AM 6A Mod

Postby radioceo » Sun Nov 11, 2012 1:47 pm

I'm not sure you accomplished anything. According to the BE website, the mod consists of replacing C5 and C8. C5 is replaced with four 330uf in parallel......likewise for C8. The mod kit thus contains two circuit boards and eight capacitors for each module.
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Re: BE AM 6A Mod

Postby AM GUY » Thu Nov 15, 2012 7:45 pm

To the original poster, what kind of processing are you feeding that AM 6A? I have the BE AM-1A, and I'm using the simple Inovonics Model 235 AM Processor, don't confuse it with the simple Inovonics 222 Processor that is just for meet NRSC-1.

My BE 1 KW Box will have been on the air as of December of 2012, 4 Years. No problems with the PA's or the modulator card. I had a Omnia 3 AM Processor I used with it in the beginning, and it was awful. Too much bass, muddy, and no highs. We put the Inovonics 235 in that has the AGC, Compressor, EQ, the basic stuff for AM Processing and is sounds great, and the BE seems to love it! :D

I bought a spare PA Card for the BE, and being I can only do certain things, I'll keep this in mind. The only other thing I have been told about the BE 1 KW box is that the High Voltage "Switching" Power Supply could go bad, or the little power supply going to the controller could go bad, but nothing in this world is built 100% perfect.
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Re: BE AM 6A Mod

Postby amradiofan » Thu Nov 15, 2012 8:32 pm

The original post is from our engineer, who may not be on the board for a bit. I'll answer!

We have two different sets of processing running our B-E AM6A.
The first is a mono-stack, of CRL separates. Left and right Studio feeds are combined through a "stick on" RDL 600 ohm box, then:
App-400 "audio prep processor, SEP-400A spectral energy processor, and a PMC-450 Peak Modulation Controller with built-in NRSC compliance.

Through a stereo switcher, we can select that stack, or the current stereo one, which actually is shared with our FM translator!

Main studio feed goes to:
CRL SGC 800 Stereo Gain Controller; (2) Texar Prisms, one left, one right; Stereo Distribution Amplifier and meters by RDL (one side to final FM box, one side to AM stereo); CRL SMP-900-A CQUAM stereo matrix final processor for AM stereo.

We do stereo mainly, have had no loss of range or modulation running CQUAM. It seems to get "out" better in some difficult signal areas of town, and the range seems
better, but BOTH sets of processing get us compliements from listeners. I'd very much like to find a CRL AM Amigo, but they're mighty scarce.
Sample here recorded off-air from tuner:

http://www.i1430.com/audio/am-sound.mp3
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BE AM 6A Mod

Postby Dave Loudin » Thu Nov 15, 2012 10:11 pm

Nice demo! Gibb brother songs always have very open mastering.
What's that do....?
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Re: BE AM 6A Mod

Postby AM GUY » Thu Nov 15, 2012 10:57 pm

Wow, that does sound good! Was that recorded off an air monitor? Gee, it sounds as good, or better than CD Quality! I think I was in High School when that song came out, and heard it on 1510 WLAC-AM, back when it was a Top 40/CHR Station.

I think the song was Barbara Streisand singing (back in her "SuperWoman" days) and the Bee Gees did back ground vocals and wrote that song. It's been so long ago, I can't remember, but it did sound great!
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BE AM 6A Mod

Postby Dave Loudin » Thu Nov 15, 2012 11:22 pm

Yes, that was Streisand singing a Gibb song. The arrangement was classic Bee Gees.
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Re: BE AM 6A Mod

Postby amradiofan » Fri Nov 16, 2012 5:09 am

Yes, that was recorded off-air! We use a Carver TX-11A for monitoring in-studio and in-engineering so we know
what is REALLY going out on the air. The recording was made from the receiver patched into a production board in one of our studios,
and not altered at all! Proof of the sound AM can offer! And yes, it's within the 10khz NRSC mask.

Thanks for the kind words.
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