Some of the wild and crazy things we have done to get back on the air.

[rew]

Some of the wild and crazy things we have done to get back on the air.

I know there are a lot of super sharp engineers on this board. All of us have done some crazy things to get a station back on the air when there was just no other way to get back on. Some of these ideas were genius and I am sure some were really bad. I would really like to hear some of those stories.

Merry Christmas to Everyone
Robert Williams

 

[fm-engineer]

Re: Some of the wild and crazy things we have done to get back on the air.

How about a few HV transformers up on wood blocks.........

 

[stacker]

Re: Some of the wild and crazy things we have done to get back on the air.

Creative use of automobile jumper cables comes to mind.

I once returned an old Gates 10-G to the air with ketchup. Seriously, failed de-icers and the resulting hi vswr blew a hole in the low pass filter. The carbon trail wouldn't allow a restart at any power. I pulled the low pass filter apart, looked around for something to clean the copper with, and settled on several packets of leftover fast food ketchup. Smeared the ketchup on the copper and anywhere else where the fire trail was visible, waited about 30 minutes, and cleaned it up. The copper looked like new (except for the hole that the arcing had created). Put it all back together, hit the plates and it worked. That transmitter ran for another 6 months before it was replaced.

 

[chriscollins]

Re: Some of the wild and crazy things we have done to get back on the air.

I wired some AV100 AudioVault Cards on a Motherboard on a cardboard underbox to create a makeshift server after a lightning strike. It had a massive collection of drives and all kinds of adapters stepping the drives down to 50 pins... Man, that was a long time ago. I've got some good IT ones. I had two power supplies hooked up and jumped on, to power all the drives and the computer. The drives all had a piece of cardboard in between them and were stacked. I will post some more later when I get on a computer...

 

[rew]

Re: Some of the wild and crazy things we have done to get back on the air.

I rebuilt a plate blocker in a CCA FM5 ? several years ago. It was Thanksgiving weekend so I used several of the cooking bags like some people cook there turkey in. A lot cheaper than the kapton sheet I later rebuilt it with. I ran the turkey bag blocker at about 3kv instead of the normal 5kv+ and kept the power down around 2kw instead of the normal 4500. I was so pleased that this worked I left it running at this power for about a week till I could get the correct parts. I never got the courage to hit it with full power. I think about this everytime Thanksgiving comes around..

 

[rew]

Re: Some of the wild and crazy things we have done to get back on the air.

At another FM the local power company decided that our power pole needed replaced. So they pull there trucks in without saying a word to any of the station staff and drill a big post hole about 10 feet from our current pole. The first that we knew about anybody working out back was when the FM transmitter shut down. I brought it back on low power and it held long enough for me to see about a 20:1 VSWR. The power company had centered our 1 5/8 inch line with there drilling machine. I ran to where they were working and told them what had happened. The formam ask," does this mean you are not broadcasting?" I told him that was correct.
Now I am down in the South and a lot of small town stations carry local high school football games as was our case. We had a team that had not lost a game and was in the last round of the region playoff. Broadcast was to start in 3 hours and the station had really sold this game as it was over 100 miles away.
The foreman told me he was planning to listen to the game tonight. His son was playing, another worker spoke up and said the same thing.
The next responce I got from the power co forman was not what I expected to hear. " What can we do to help?" I told him I needed a back hoe to dig a hole big enough for me to work in. He sent one of the guys to office to get there back hoe and told the others that if they wanted to help to do or get anything I needed and if they didnt want to help they could clock out and go home. NO ONE LEFT. In less than 30 minutes I had a hole with plenty of room to work in. I cut out about 3 feet of damaged line and slid a 4 foot piece of 3 inch pvc over one end of the cable. This was to be the cover for this rigged splice. I slid a piece of 1/2 inch transmission line into the center conductor of the 1 5/8 line this will make the connection for the center conductor. A power company appliance repairman had come to see if he could help, he grabbed a small torch and carefully soldered each end. I then used about 10 pieces of #8 copper wire and spaced them around the shield of the 1 5/8 line and secured them with a pipe clamp on each end. Slid the pvc pipe over it ,filled each end with silicone rubber and prayed as I walked back to the transmitter. I kept thinking there is no way this splice is going to work. Maybe on an AM station but not a chance on FM. When the transmitter came back up it was on hi power and only showed about 1.6:1 VSWR.. I dropped power about 50% to play it safe. When I got back outside they had stuck 10 ground rods into the ground around the hole and roped it off with yellow "Crime scene" tape that the local Police had brought by. This worked till we could get a new line installed which the power co crew helped with by digging the trench for the line. They also paid for everything.
We were back on the air with 20 minutes till game time. All the time I was in the hole working the local fire dept had a rescue unit and a paramedic on standby just in case there was any kind of problem or anyone got hurt.
This is a good story of how a small town helped out in the stations time of need. The power co didnt try to get out of it , they wanted to help the police and fire dept were not called they heard what had happened and came to see if there was anything they could do to help. Small town radio has its advantages!

 

[Kent T]

Re: Some of the wild and crazy things we have done to get back on the air.

IPA in an MW 50, used a Crown DC 300A for a driver stage . Worked very well for 6 months, when we had a real one.

 

[kenglish]

Re: Some of the wild and crazy things we have done to get back on the air.

Long before my time (late 40'/early 50's), KSL-TV's tower on Farnsworth Peak came down in a winter storm.
The engineers built a small tower on the roof of the transmitter building, and built a VHF Channel 5 antenna out of stove pipe.
They ran with it for months, while constructing a replacement tower and "store-bought" antenna.

 

[The Wattcher]

Re: Some of the wild and crazy things we have done to get back on the air.

Many years ago, lost the filament transformer in a kilowatt AM transmitter.
Used a 6 volt tractor battery to power the filaments. It was a day timer, so
we charged the battery after sign-off. It took a couple days to get a replacement
transformer.

 

[K4WRF]

Re: Some of the wild and crazy things we have done to get back on the air.

We received a call that a station was having antenna tuning unit problems and needed someone with bridging equipment, pronto! Upon arrival, discovered the LTU was good but xmission line was shorted. To get him going for the *time being*, went down to parts place and purchased 120' of RG-8/U and turned it back on the air (1/.250 kw 1240 kHz). We ordered up a reel of Andrew 1/2" Heliax to replace the coax and their local contractor said he would install it as soon as it arrived. 26-years pass, and I get call from same station with antenna problems, off-the-air and and need bridge, ASAP! Got there and soon discovered the same RG-8/U coax in use, the Andrew was still in the unopened container in their storage room. No, it was *NOT* the coax but .001uf 292 in the shunt arm of the ltu which I happened to have in my stock. Also replaced the coax with the Heliax while I was there... Sometimes, it just takes time!!

All the best!

w/

 

[Kmagrill]

Re: Some of the wild and crazy things we have done to get back on the air.

Our group had a 100kW FM on a 500' tower about 1/2 mile from the Rio Grande near Brownsville, TX. Mexican nationals constantly used the beacon for 30-06 target practice. In the process, they frequently shot holes in the antenna and feedline. This happened several times per year. One particularly rainy week, we noticed that the feedline pressure was zero, again. Before a crew could ascend the tower, the line filled with water, resulting in destructive arcing from the Harris FM20H which had no VSWR protection. Upon arrival, we noticed burnt insulation on the coax at the point where the coax turned to go up the tower. We had a couple of spare fittings, so we cut the burn out, in the rain, and made a temporary repair, but water was still running down the inside of the coax from the hole or holes at the top. So, we put a little drip loop in the line and drilled a 1/4" weep hole at the bottom to drain the water. Sure enough, the transmitter came up and we ran at 1/2 power for about 2 weeks until the line was replaced.

Sometime later, a guy wire was cut but the tower stayed up, with a significant bend at 250 feet. To save the tower, the guy wire was tied to the bumper of the GM's Ford Bronco which was then inched forward until the tower was close to straight. A couple of days later, the Bronco was found vandalized and totally trashed.

 

[boiseengineer]

Re: Some of the wild and crazy things we have done to get back on the air.

Remember the old SA DATS receivers?
Our only one died one afternoon. No networks. Nothing.
Grabbed an un-used Zephyrus satellite receiver (for Video carrier with subcarriers) out of storage. Set it to the transponder and fed the IF out into the DATS & it worked! Ran that way for a week before SA sent me a new divide by 64 chip.

The old GE 4BT50A1 ran on various borrowed Ham Shack transformers for the 1500 and 3500 volt supplies waiting for rebuilds. The 9600 V supply ran on 2 transformers for nearly 2 weeks. Just a bit of hum and it was running about 8 kw. But it was on. Something good about the old transmitters that you could get RF out of them one way or another.

 

[chrish]

Re: Some of the wild and crazy things we have done to get back on the air.

Must be a real thrill to live along the Mexican border in Brownsville, there is no amount of money you could pay me to live in that shooting gallery, I had a friend whose parents had a beautiful home there and had to sell it for chup change to get out.

I used a Crown D-75 as a temporary fix for a Gates BC-5P audio driver deck, it sounded so much better than the under designed original I decided to make it
permanent. Horrible horrible transmitter, The Gates was a IM distortion tinker toy in comparison to the RCA BTA-T that sat next it. The third transmitter an
RCA BTA-1R had a bigger modulation transformer and heftier power supplies the the BC-5P

 

[BobOnTheJob]

Re: Some of the wild and crazy things we have done to get back on the air.

drilled a 1/4" weep hole at the bottom to drain the water. Sure enough, the transmitter came up and we ran at 1/2 power for about 2 weeks until the line was replaced.

If you're in the middle of nowhere without a drill, a little elbow grease and a "greenie" will make the needed hole as well. Amazing how quickly the SWR drops back with this marvelous remedy.

 

[greg.hahn]

Re: Some of the wild and crazy things we have done to get back on the air.

Had a site with an air conditioner mounted above the ceiling....and directly over the Harris FM 2.5K transmitter. The AC condensation drain backed up and started dripping into the transmitter, and we were off.

I walked in to the transmitter room and saw all that water dripping in to the transmitter, and I about had a cow. I called the station and told them what had happened, and that the transmitter was full of water. I had no idea how long it would take to get it back on.

Removed the 5CX1500 tube and dried the socket and everything else I could find that was wet with a hair drier. After it all seemed dry, I fired it up.

POW! A high voltage choke shorted to ground. I put it up on a two by four and tried it again.

It came up! Then...

POW! The screen supply power transformer went out.

I had an OLD Gates 1KW transmitter there that somebody gave us, always intending to make it work as a backup but never having the money to do so. So I rummaged through there and pulled out a transformer that wasn't quite right, but it was in the ballpark.

It had a 120 volt primary, so I cut up a line cord and attached it to the primary leads, then wired the secondary in to the screen supply of the Harris. The line cord ran out the front of the transmitter.

I turned on the high voltage and it all seemed to come up...lots of voltage, almost no current, and a few watts output. Then I plugged that line cord in to an outlet on the wall.

60% power! It was one of those glorious moments. I swaggered in to the GMs office and told him the status and that I'd be ordering some expensive parts from Harris. Considering the alternative, he was thrilled.

It ran that way for 3 days until I could get the right parts and get them in.

 

[K4WRF]

Re: Some of the wild and crazy things we have done to get back on the air.

Once used a Sears Shop Vac to replace the blower on a Gates 2.5 kW FM transmitter. It took quite a bit of crafting using a plastic trash can and copious amounts of duct tape. Ran it at 1/2 power and couldn't believe that vac motor lasted for three days until new fan arrived...

 

[grich]

Re: Some of the wild and crazy things we have done to get back on the air.

My mentor used a strap made from a Pepsi can (back when pop cans were made of REAL metal) to put a Gates FM2.5H back on the air...made it into the newspaper. Hated those 5CX1500A's when they would arc internally, and that 50-ohm wirewound resistor in the plate supply line would blow chunks out of the top of the rig. I still plug my ears when turning on transmitters 30 years later. ;D I learned to leave the filaments on during the off-air times to keep the grid structure from warping, and it seemed to help.

Also helped him deal with a FM20H3 that burned up the bottom of the feedline due to water ingress. Didn't have to make a hole for drainage...the arcing took care of that. The reflected power also arc-welded the PA cavity door shut; I got to chisel that open.

 

[Kmagrill]

Re: Some of the wild and crazy things we have done to get back on the air.

Once used a Sears Shop Vac to replace the blower on a Gates 2.5 kW FM transmitter....

I forgot about that one. I used an electric leaf blower for the same purpose on a CSI 5kW FM until a new Rotron blower could be shipped in.

 

[rew]

Re: Some of the wild and crazy things we have done to get back on the air.

Hey grich, I still have a FM2.5H I have to keep running. Not much trouble with it. What did he use the Pepsi can for? Just incase I ever need to know.

 

[Kmagrill]

Re: Some of the wild and crazy things we have done to get back on the air.

Hey grich, I still have a FM2.5H I have to keep running. Not much trouble with it. What did he use the Pepsi can for? Just incase I ever need to know.

I'm guessing anode strap. I burned up a pair of them on an FM20H3 once because I got the hose clamp slightly crooked during maintenance. Opened up the failed transmitter to a cascade of little aluminum ball bearings where the anode straps had been.