Inside the ECO-4

FM does it with frequency!
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abwdvm
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Inside the ECO-4

Post by abwdvm » Fri Jun 29, 2018 12:20 pm

Got the ECO-4 out trailer-ed home and in the shop.
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Last edited by abwdvm on Fri Jun 29, 2018 12:46 pm, edited 3 times in total.
technician at an 1000w AM station in Texas

Nathaniel Steele
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Re: Inside the ECO-4

Post by Nathaniel Steele » Fri Jun 29, 2018 12:37 pm

Fingerstock is missing a few fingers, but otherwise that looks pretty good. I'd pull the tube and check the rest of the fingerstock though.

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Deep Thought
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Re: Inside the ECO-4

Post by Deep Thought » Fri Jun 29, 2018 1:00 pm

Be sure the fingerstock is actually contacting the tube anode. That looks kinda loose.

The tuning adjustments (tune & load) are both at the ends of their travel. Either they are grossly misadjusted or something else was wrong like the antenna load. That could explain the very low apparent efficiency displayed in another thread.

If you've never worked on one of these before be very careful to not start bending what may look like random bits of metal in the tube cavity. Those bits are necessary to make the thing work right and need to remain in those shapes. :lol:
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

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abwdvm
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Re: Inside the ECO-4

Post by abwdvm » Fri Jun 29, 2018 1:07 pm

I assure you I have not worked on one of these. I understand how important those fingers are now. Once I get some time next week I will take a closer look. We also found what looks to be a spare tube.

IPA? Transformer set to 240 and +10?
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technician at an 1000w AM station in Texas

Nathaniel Steele
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Re: Inside the ECO-4

Post by Nathaniel Steele » Fri Jun 29, 2018 1:26 pm

Only the middle picture was coming up for me last time....yeah I'd look at tuning and loading. I've not worked on many of these, and had someone with me who was more knowledgable of them as they are a little wierd from what I understand (and apparently no two boxes were ever quite the same!)

Not sure about the transformer, it's either set for 230V input or 250V input, my intuition says 230V (230+10=240, but it could be 240+10=250) You could always disconnect the secondary and measure whih way it goes as you change the taps. or if your new location is 240V or 208V move the red wire to 0 and the white to 240 or 208.

That one is the cleanest ECO I've ever seen....All the ones I've been around were in Colorado in Dusty Air cooled (Fans, Not A/C) rooms in the middle of dusty cowfields....

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Re: Inside the ECO-4

Post by TPT » Fri Jun 29, 2018 2:02 pm

There is a flexible metal plate in front of the tubes with a bunch of holes drilled in it. If you take off that black cover on the front of the transmitter you'll see it. The book--if you have one--should tell you how many holes down it should be connected for your frequency. If that is attached at the wrong place, it may the transmitter was originally on a different frequency. That would explain why the loading/tuning controls seem to be at the end of their ranges

Also--while you have it in the shop--be sure and check and see if the front panel cranks actually do anything. As I mentioned, there are Teflon (or some such) plastic blocks connecting the controls to the threaded rod that moves the sliders..or not, if the little hex-head set-screws have come loose.

Lee_Wheeler
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Re: Inside the ECO-4

Post by Lee_Wheeler » Sun Jul 01, 2018 12:25 pm

The initial turn on might be interesting. I had a situation where I called in to revive a dark station and the previous owners / engineer set traps everywhere out of spite. One of many was to crank the tuning and loading as far in the wrong direction as possible.

...Lee

Joe Friday
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Re: Inside the ECO-4

Post by Joe Friday » Tue Jul 17, 2018 6:27 pm

Second checking the anode finger stock. One box I took care of for a number of years had a piece of 3" strap wrapped around the tube anode to improve contact with the fingerstock. We eventually researched and found the original supplier for the fingerstock and replaced it. The finished job doesn't look like much, but it has been in service for about 3 years now without any further issues.

The ECO boxes were certainly "value engineered", almost to the breaking point in some cases. And as others have pointed out, some parts are difficult to find now. However, these boxes can be quite "hearty". Another engineer and I resurrected one that previous engineers had given up on, and had been off the air for over a year. Inside two days we had it back on at 100% power. It has been running well for the last four plus years.

If the plate transformer is the upgraded part from the ECO-6 and checks out OK, It would be worth spending some time on, IMHO.

Good luck!

Kevin

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