Worst FM Transmitter

FM does it with frequency!
ChuckG
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Re: Worst FM Transmitter

Post by ChuckG » Tue Nov 03, 2015 4:29 pm

george.shinas wrote:Hi everyone,

I was trying to purchase a 50W FM transmitter for one of our communities up here north of Canada, from BW Broadcast. They have a local retailer here in Canada http://www.sonotechnique.ca but according to them the 50W transmitter is not approve by ICC yet. Is there any other brand of transmitter that you could recommend? What would be the best 50W transmitter out in the market? Thank you very much.
In that same price range, Nicom has a 150W transmitter that's Industry Canada approved (NT150)
They also have a NT30H capable of 55 watts, but no mention of where it's approved.
Progressive Concepts has a 50 Watt (TXF 50). There are likely other choices as well.
Of the two my preference is for Nicom.
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Chuck Gennaro
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JustMe
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Re: Worst FM Transmitter

Post by JustMe » Tue Jan 05, 2016 2:17 am

In my opinion the Gates DAX3 is NOT the worst transmitter. However, what rankles me is Gate's sky high prices for parts and repairs. The DAX3 seems a rather stable transmitter and we have had good luck with it. We have lost two power output modules in the last three years. One was under warranty, the other we sent back for non-warranty repair. It took three months and a number of calls to get Gates off their duffs to repair it. Not good. It was $850 flat rate for repair. It would seem to me a fairer cost would be the actual problem with module and what time and parts are needed for repair. You had Better check those internal fuses before sending one off. Strange we have had two power output modules fail when the transmitter is rated at 3KW and we are only operating it at 1KW. Yes, we have a good surge protector across the mains feeding it and the fans are operational.

The transmitter has two internal power supply modules, one 48V and one 12V. These are both made by a company called Mean Well. In the past three years, both have failed. Gates wanted $450 for each module. I was able to purchase each, exactly identical to the originals, on the internet for $49. I don't begrudge any business making a decent profit. However, this all seems rather excessive.

bbiermann
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Re: Worst FM Transmitter

Post by bbiermann » Tue Jan 05, 2016 1:34 pm

There are a number of "bad" FM transmitters out there. There were some Sintronics that had many issues, mostly the later series. Lack of cooling to driver tubes on their 3 KW FM would burn out the 4CX250's in short order.

I also had a few bad experiences with QEI's. The CCA's always did well for me, though I know the ones built pretty much after 1994 became questionable due cost cutting measures. I have had both the E series built in New Jersey, and three different G series built in 1992 in Georgia. All units are still in service and doing fine.

Of course, tube life is not what it used to be for any transmitter. Seems to be a major issue of late. I don't think it's a transmitter issue, as it is a quality control issue on the part of tube manufacturers.

kcbooboo
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Re: Worst FM Transmitter

Post by kcbooboo » Tue Jan 05, 2016 2:29 pm

Regarding the DAX3, that is an AM transmitter, however Harris did release a bulletin about replacing the fans in those two power supplies because they were failing, and the supplies would overheat and shut off. I did that replacement on a DAX1. They were even providing the fans at no cost a few years ago.

Bob M.

jeeisenz
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Re: Worst FM Transmitter

Post by jeeisenz » Mon Mar 28, 2016 3:37 pm

Bob,

Must have missed that bulletin. We recently had to replace the 48V PS in our DAX-1. Harris wanted $400 for the replacement. Found the same replacement for $50 on a reputable electronics site.

Fun trying to tear that power supply shelf apart to get to the damn thing...*shudder*

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Re: Worst FM Transmitter

Post by ChuckG » Mon Mar 28, 2016 4:31 pm

bbiermann wrote: I also had a few bad experiences with QEI's.
.
Did anyone not? :lol: I kept a box of band-aids on top of that thing because of all the unfinished, sharp metal edges.
Agreed on the CCA E-series. Those FM's were tanks.
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Chuck Gennaro
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kcbooboo
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Re: Worst FM Transmitter

Post by kcbooboo » Tue Mar 29, 2016 3:44 am

It was a Harris Service Bulletin, issued in 2008, but I probably didn't see it for several years. They're probably no longer offering free fans. This was back when you could actually FIND such things grouped by equipment model on their support site. Here are the details:

BULLETIN NO: AM-568-JK DATE: Jan 15, 2008

EQUIPMENT: All DAX Series AM Transmitters Manufactured prior to March 2007

SUBJECT: Low Voltage Supplies Cooling Fan replacement.

We have upgraded the internal cooling fans of the 12Vdc Supply, Harris part number 736-0376-000 and the 48Vdc Supply, Harris part number 736-0377-000. It was found that the internal fans as provided from the vendor contained a bearing not suited to the continuous operation of a transmitter. Hence the bearings were prematurely failing, allowing the supplies to over-heat and thermally shut down. The vendor has identified a direct fit, form and function replacement fan with a more robust bearing, better suited for continuous operation. Harris will initially provide these replacement fans upon request at no charge until Jan of 2009. The fans can easily be identified, visually. When viewing the supply, observe the 4 center holes of the fan cutout. If the label behind the holes is “Orange”, the fan requires replacement. If the label is “Green” in color, you have the upgraded fan.

Parts Supplied: Fan, Harris p/n 430-0418-000. 2 required per transmitter.

Tools Required: Assorted screwdrivers - medium tip, assorted nut drivers.

Time Required: 30 minutes.

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KPJL FM
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Re: Worst FM Transmitter

Post by KPJL FM » Tue Mar 29, 2016 7:48 am

ChuckG wrote:
bbiermann wrote: I also had a few bad experiences with QEI's.
.
Did anyone not? :lol: I kept a box of band-aids on top of that thing because of all the unfinished, sharp metal edges.
Agreed on the CCA E-series. Those FM's were tanks.
QEI - Questionable Engineering Inside.
Trim to fit, paint to match, tune for minimum smoke.

ChuckG
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Re: Worst FM Transmitter

Post by ChuckG » Tue Mar 29, 2016 2:31 pm

KPJL FM wrote:
QEI - Questionable Engineering Inside.

Painted bright red so you can find them in a smoke-filled room.
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Kelly
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Re: Worst FM Transmitter

Post by Kelly » Thu Mar 31, 2016 7:15 am

Quasi Electronics Indeed
Skype:kellyalford Twitter: @KellyAlford

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RGORJANCE
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Re: Worst FM Transmitter

Post by RGORJANCE » Fri Apr 01, 2016 8:22 am

I haven't posted on QEI FMQ-5000 that I work with, but this will cover that.

I have experienced troubles in several areas over at least ten years of working on the rig.

1) blower motor bearings replaced about every three-four years
2) have had two exciter failures
3) IPA failures-maybe two in all those years

Had a tube socket fall apart during a tube change once. Lower part of socket was held in place with 6-32 nylon screws that deteriorated over time. I fabricated a high tech chunk of 2 X 4 to put under socket when putting tube in socket. :lol: Also had a chip fail in controller.

Other than that, it has really been pretty decent considering it gets whacked by lightning a lot.

I have to agree that mechanically, it is crude and that does present awkward work at times. I have seen much worse-----Armstrong for example.

QEI support has been very satisfactory and I have no problems in that area.

Fossil

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kkiddkkidd
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Re: Worst FM Transmitter

Post by kkiddkkidd » Fri Apr 01, 2016 10:03 am

RGORJANCE wrote: QEI support has been very satisfactory and I have no problems in that area.

Fossil
Are they back in business? I tried to get an IPA repaired sometime in the last few years and was told that they were closed except for small parts sales.

The 3.5 that we just retired to STBY was absolutely a lightning magnet. I finally installed enough AC and tower protection that we got it stopped but for the first year or so of my tenure with that box, I walked in numerous times to find fuse holders laying in the floor. Also replaced the blower once and a couple of IPA's myself and a couple of front panel meters. And a sack full of fuse holders...

The autopower control never worked but it was stable enough that it only occasionally took a small adjustment via remote.
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RGORJANCE
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Re: Are they back in business?

Post by RGORJANCE » Fri Apr 01, 2016 12:42 pm

Kevin:

I just this last month got two IPA' repaired and the whole combiner, splitter and IPA's tested together as a system.

Contact Bob Brown at QEI. He is a good guy! (tell him "Goucho sent ya") Old guy thing.

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kkiddkkidd
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Re: Worst FM Transmitter

Post by kkiddkkidd » Fri Apr 01, 2016 5:23 pm

Thanks for the update. The only QEI left in this part of the world is the one that I referenced and it is a cold stby at a site with a new Nautel. Bill is a good guy and glad that they are back in business even though I don't think much of his final product...

Later,
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KK Broadcast Engineering
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ChuckG
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Re: Worst FM Transmitter

Post by ChuckG » Fri Apr 01, 2016 8:48 pm

Bob Brown was always super to work with, as was Ed Etschman. I'm not sure if Ed is there any longer.

The first QEI I installed was a FMQ-10,000. 1991 or so. Factory guys flew out to do the checkout. Looked good.
Here's it's history over the 16 years I maintained it:

Less than a week after installation the rectifier stacks shorted, nary a cloud in the sky. Replaced. Two weeks...shorted again. Replaced. And.... shorted again. 4 hour drive each time. I started building extra rectifier boards just to have on hand.

Discovered there was no R/C snubber on the HV line. I added one. Also added enormous varistors on the HV transformer primary and the AC entry panel.
Transmitter ran a few months and I thought I was victorious...until it blew the rectifiers again.
I doubled them up, putting two stacks in series for each leg. Added strips of teflon in between so they woudn't arc to each other or to the rear panel door.
No further rectifier failures.
Keep in mind the Collins that preceded it still has it's OEM rectifiers from 1967. I'm told QEI added snubbers and doubled the stacks as a production change later on.

Then the Harmonic filter shorted.
Then the HV bypass caps shorted. This is the least-fun thing to reach in the transmitter. You have to remove the tube, then the socket, then reach blindly behind the tube shelf, bend your arm down 90 degrees to reach the caps, while your other arm is underneath the cavity but over the rectifiers to reach the mounting screw...all while dodging the sharp metal edges everywhere including those under your chin.

Replacement harmonic filter shorted. Replaced.
Less than a year later the harmonic filter shorted a third time. This time I fixed it myself, doubling up the teflon sheets and dressed all the sharp metal edges with a dremel tool. So far no further failures.
Then the problems started with the digital controller board. It's in a metal box with very little ventilation. Added a small fan and replaced the caps that cooked over time. No further problems.
Then an IPA cable failed, taking the IPA with.
Then the teflon blocks the socket sits on began to fall apart.
Then the coarse tune inductor wing nuts welded themselves on a lightning hit.

The APC never did work right, but when the transmitter ran it really didn't need it. VSWR foldback was separate...provided you consider a hard switch to 25% power "foldback".
Filament rheostat had a 2-year lifespan and opens the circuit when it fails...about the same lifespan as the (German, imported, expensive) PA blower.
On the other hand, the original PA tube, a YU148 of all things- had a 7-year lifespan!

I no longer maintain that transmitter but know the guy who does. Last I heard the fun continues.

Second QEI I installed was a Quantum 300E. Shut down at random intervals. Opened it up and found the tiny coax cables that feed the final transistors had never been soldered at the factory, just laying on the pads. No further problems after fixing that.

There was no third QEI.
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