Worst FM Transmitter

FM does it with frequency!
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Kelly
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Worst FM Transmitter

Post by Kelly » Sun Aug 03, 2014 6:18 pm

By request; in your experience, what do you consider the worst FM transmitter? Here is a list that I can think of (in no particular order):

QEI
CSI
Energy-Onix
Harris
BE
Continental
Collins
Armstrong
Bext
McMartin
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TPT
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Re: Worst FM Transmitter

Post by TPT » Sun Aug 03, 2014 6:34 pm

Energy-Onix is an OK transmitter. It's not all that efficient, and the tuning is, in a word, strange.

Usually if you change a tube in an FM box, a minor twist of the tuning and loading controls gets things back to normal.
Not with the Energy-Onix. Crank and crank and crank--and it comes back up to power. (May also be the rebuilt 3cx3000A7's).

Once I figured this out, I get along with my ECO-4.

level42
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Re: Worst FM Transmitter

Post by level42 » Sun Aug 03, 2014 9:52 pm

I'm fine with an Energy-Onix Eco box...take care of a bunch of them...always easy to repair...nothing proprietary in them.

My least favorites are the RVR/Armstrong tube boxes...especially the FM3500T. They were not built to be worked on at all. Anything QEI (tube or solid-state) would be a close 2nd.

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Re: Worst FM Transmitter

Post by ChuckG » Sun Aug 03, 2014 10:01 pm

QEI FMQ series. Worst thing that's still on the market.
Radio-shack quality parts stuffed into an undersize cabinet with sharp edges everywhere. The one and only unit I installed required:
Doubling up the diodes in the rectifier stacks so they wouldn't keep blowing
Adding a R/C snubber (factory didn't)
Wallpapering the rear door with Kapton so the HV supply wouldn't arc to the cabinet.
Weaving teflon between individual diode stacks so they wouldn't arc to each other.
Building a DC differential amplifier to get a remote IP reading.
Auto power control never stayed stable, Undersized coax to the IPA combiner, undersize rheostat for filament adjust...both melted down within 6 months. Harmonic filter ran at it's limit at 10kW, no headroom for lightning. And you can't reach one of the HV doorknob caps without removing the tube socket....

Oh, so being a glutton for punishment I installed a QEI Quantum (solid state) for the same station. Is it asking too much for the factory to solder the PA transistor B+ leads? Apparently it was.
"Frequency agile" ...except for that having-to-retune the entire PA thing. With compression caps. Yuck.

Georgia-built CCA's were an inconsistent lot, especially towards the end. Jersey-built were solid.

TPT, the only issues I had with the ECO's was inaccurate drawings. I had to call Bernie for things I shouldn't have to call the factory for. Outside that they ran pretty well.
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Kelly
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Re: Worst FM Transmitter

Post by Kelly » Mon Aug 04, 2014 9:38 am

My vote is also that QEI is the worst FM transmitter manufacturer of all time, tube and solid state. Sharp metal edges and points used in a PA cavity? Untreated paper dielectric between windings in the HV supply filter choke? Fuse holders for PA modules rated at less current than the PA module draws in normal operation? And forget about the transmitter actually making TPO or passing a proof of performance, and that's right out of the crate! Qasi Electronics Indeed.
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COMMENG
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Re: Worst FM Transmitter

Post by COMMENG » Mon Aug 04, 2014 11:58 pm

As much as I like Collins transmitters, the 831G-1 had the most finnicky IPA neuralization system I have ever encountered.

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RGORJANCE
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Re: Worst FM Transmitter

Post by RGORJANCE » Tue Aug 05, 2014 6:09 am

Armstrong 20KW FM later converted to a 25KW rig.

OMG, where oh where do I start? Burned up output connection. Nearly impossible to take it apart. Cavity constructed outside of xmttr, then installed. Screws not accessible unless metal carved out of rear rack support.

Driver stage failures, 100# driver requires two people and a ladder to remove, and replace. Scary!

Retubing rig takes two people and trying to retune it to get any forward power requires the services of the "Wizard of Id" with Merlin and Mim standing in the wings just in case.

Removal of bad blower motor requires two people to get it out, three people to reinstall it.

Blower noise almost as bad as early Harris FM-20G,H.

Everything on the rig is grossly inaccessible. A terrible mechanical design...possibly the worst I ever encountered since getting into bcstg in 1956.

In defense of it, however, it is somewhat reliable.

Fossil

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KPJL FM
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Re: Worst FM Transmitter

Post by KPJL FM » Tue Aug 05, 2014 1:51 pm

Either tube or SS QEI.
QEI = Questionable Engineering Inside. :twisted:
Trim to fit, paint to match, tune for minimum smoke.

brandonb959
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Re: Worst FM Transmitter

Post by brandonb959 » Wed Aug 13, 2014 3:11 pm

Bext Solid State.....terrible.

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davek
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Re: Worst FM Transmitter

Post by davek » Thu Aug 14, 2014 2:30 am

Harris Z-10.
* The power supplies need to be fed on a steady diet of 30A fuses - can't get any more than a few weeks before another tap fault!
* PA backplane is a PITA to repair/replace :evil:
* Flexstar exciter - screen backlight almost dead and prone to locking up

Kent T
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Re: Worst FM Transmitter

Post by Kent T » Thu Aug 14, 2014 8:03 am

QEI for the win. Any model they made. Taught you profanity better than 30 years in the US Navy. Questionable Electronics Inside.

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kkiddkkidd
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Re: Worst FM Transmitter

Post by kkiddkkidd » Fri Aug 15, 2014 5:55 pm

#1 #3a Energy Onix NWS TX. I installed an EO NWS tx and upon hooking up the audio, it sounded awful. Bernie finally let me know that the screw terminals marked AUDIO was for composite (I didn't know that wx tx's were stereo) and that I should hook the balanced audio up to an unmarked unbalanced BNC jack on the back panel of the controller. I eventually used an RDL amp to remove the expected px line hum. I don't think that they did a full alignment at the factory. None of the automatic transfer functions worked until I did a top to bottom realignment of the controllers. We swapped the RF modules 5 times as I recall. The first few sets glowed. The Q's were running so hot that you could see them glowing thru the fan openings. Total life at full power... Minutes. It was finally replaced just a few years later with a Crown wx tx.

#2 Henry. Possibly worse than QEI but I didn't have to work on it unless a buddy was out of town.

#3 QEI. I have a 3.5 that we finally got settled down and it operated reasonably trouble free for a few years. It has many odd quirks. Having to be power cycled after power quality issues. MANY destroyed front panel fuse holders following minor lightning strikes. Power control non-operative. Spurs from IPA. Blower. Impossible for a full grown guy to work on.

#3b Energy Onix. Eco22 to be exact. POOR efficiency. POOR tube life. Weird failures. While discussing the poor efficiency with Bernie, he would just repeat that it should do better than that. Yes, I know it should do better than that but what do I do to make it more efficient? It should do better than that! Yes Bernie, I know,,, etc, etc. I have an Eco5 that is reasonably efficient and gets decent tube life. It is on the top end of the band while the inefficient box is on the very bottom. Ditto on the many undocumented features. Lots of loose hardware and needlessly burned up stuff.

#4ish RVR. Actually a decent TX as long as you keep the shipping materials to send it back when it breaks. Zero documentation and the Spanish speaking support in Miami doesn't speak English (me) nor Italian (manufacture).

#5 PTek. Built in someone's garage by a freshman electronics class. Many mods made the manual obsolete and they could never produce a correct manual.

#6 BE FMi703. When it works it works OK but eats $1500 power supplies and $1000 modules for absolutely no reason. Very expensive to maintain.

Well up the list. CCA FM 10,000G's were always quirky but as long as you didn't get one that was being built in the last quivers of one of their many bankruptcy's... They were pretty good. Changing the tube was a pain but I built a "jack" to pull the tube out without removing the plate blocker. Other than the 5CX1500, the YU148 tube was probably the worst that I ever worked with in an FM.

Well up the list. Harris Z. I have 2 or 3 Z's and have had good luck and little down time with them.

There are others but this is the main part of the list that I have maintained.

Top of the list. Anything Nautel.
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Dale H. Cook
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Re: Worst FM Transmitter

Post by Dale H. Cook » Sat Aug 16, 2014 7:14 am

Henry, hands down. The worst excuse I have ever seen for an FM transmitter. Fortunately it was so heavily damaged in a lightning strike that the owner replaced it. The original owner, who my client bought the station from, built stations at the lowest possible cost because his business was building and flipping them and he wanted maximum profit at minimum expense.
Dale H. Cook, Contract Engineer, Roanoke/Lynchburg, VA
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kkiddkkidd
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Re: Worst FM Transmitter

Post by kkiddkkidd » Sat Aug 16, 2014 1:03 pm

The Henry that I have worked on a couple of times used several door knob caps for the plate blocker or maybe just some sort of bypass on the plate contact. I helped my buddy who is owner/engineer change the tube for the first time.

He wasn't feeling well and asked me to come hang-out while he changed the tube. He pulled a little on the tube. It didn't move. He wiggled and pulled a little harder. Still didn't move. With a curse and a grunt he managed to remove the tube from the socket. Except he brought out the tube side of the plate blocker and the top screw terminal on most of the door knobs.

His first comment was, "I don't know what the F... you are going to do about this but I've made a mess. A quick inspection revealed that he had just broken the solder joints in the caps and hadn't damaged the cap internals. With a few minutes and a 500 watt gun, I reassembled his "mess", put the new tube in and with a small prayer hit the plate on. And it came on. And made power. And tuned up fine.

He was supposed to replace the repaired caps but I doubt that he ever did.

I also recall it required some sort of convoluted external control logic that required a number of latching relays.

I think that TX was later sold on Ebay after he upgraded.

Later,
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Kevin C. Kidd CSRE/AMD
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Re: Worst FM Transmitter

Post by ChuckG » Sat Aug 16, 2014 9:43 pm

kkiddkkidd wrote: Well up the list. CCA FM 10,000G's were always quirky but as long as you didn't get one that was being built in the last quivers of one of their many bankruptcy's...
The "E" series came with a tube jack from the factory. You'd hook it on the tube and turn it with a wrench. Worked pretty well.
I've had pretty good luck with Jersey built CCA's, the Georgia product seemed less consistent.
I believe I hold the record as the Shortest-lived CCA employee, lol. One day. Long story and in retrospect very lucky, the final BK was a few days later.
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