Well this is, radio related, not necessarily vintage radio related but I’m hoping one of our
experts might have a suggestion for me.
I’m in the process of moving into a new property which has a 6’ page fence around it
There is an electric slide gate at the driveway who’s motor is controlled by an ESP
Micom receiver and remotes using 312mhz. The receiver is house with the motor and
drive in a large
box and appears to be weather tight. The antenna is an eight inch long 1/16”dia. Rod
mounted in the top of the box with a coax going to the receiver inside the box. When it
rains even the slightest the remotes won’t open the gate but the hard wire button in the
house will open it. Nothing appears to be wrong with the coax or the connector other than
it’s all about 30 years old.
I’m not very good with antennas never have been, so I’m open to any ideas why the
remotes don’t work when it’s wet out?????

Denny Graham
Sandwich, IL

Hm... atmospheric shorting. Are you saying just WHILE it is raining or also afterwards?

I'll guess the insulator at the antenna base is dirty and/or deteriorated so is absorbing moisture that basically grounds out the antenna... Cover the antenna with a plastic bag to see if that helps... Also spraying a water dispersant like WD40 on the base may help and even get it operating again when wet...

Could also be the receiver and/or transmitters are slightly off freq and the above is aggravating the condition...

Tom

Antenna grounding was my first thought, but then it didn't make sense to me because it would most likely not work for a while after it had rained.

Thanks for the suggestions Tom, never thought of bagging it. With the antenna, feed thru
and coax as old as it is I think I’ll try to find another one for exterior use and just replace
the whole thing from the receiver on out. The receiver by the way was replace not to long
ago due to a lightning strike I was told by the previous owner.

There is a little round window with a trimmer screw on the remotes. I’m guessing that’s
to match it up to the receiver but lacking instructions I’m not sure how you would go
about tuning them.

It appears to happen when it gets wet Nick, so I would think it could be shorting out the
signal. The previous owner warned me about it and it’s happened twice on me in the last
couple of weeks. I had to climb the fence and open it from the hard wired switch in the
house. At 70 climbing 6’ fences is getting to be a bit more difficult than it used to be.
Denny Graham
Sandwich, IL

Have you checked the batteries in the remote transmitter(s) ?

I ask because I was thinking , if the batteries are low , maybe the signal is only strong enough to operate the gate on clear days , but with the rain the signal can't quite get through ?

I can tell when my garage door remotes are needing batteries when they begin needing to be closer and closer to the door before it opens , and also if it's really cold in the car the remote has a hard time getting a signal out as well ........

Naw, first thing that I did after the closing was to put new bats in all the remotes (3). It quit raining and dried out some and the remote worked at 200' away.
Tks
Denny G

If the coax is as old as you say it's likely water is getting into the insulator between the center conductor and shield and shorting the signal out. That would be the first thing to replace before trying anything else.

Scott Todd

When it's working you can use a insulated tool to tweak the transmitter(s), for greatest range... Best done on foot, start by finding the furthermost spot it will function and then tweak the trimmer slightly to see if range improves or decreases... If it increases try a bit more, of course if range decreases go the opposite direction... Only turn trimmer a degree or so at most, a little goes a long way when tuning UHF...

Just read it works at 200' when dry, probably no need to mess with tuning...

Tom

Thanks again Tom, I’ll try that before I file them in the trash can. Three of the remotes
work at a distance when all is dry. I’ve got two more spare remotes that don’t work at all.
The reason I asked is I suspect that someone may have messed with the trimmers. If they
are that sensitive I might have a problem finding the sweet spot. I suppose if I sit down
next to the receiver and start from one end and slowly turn the pot there will be some spot
the will trigger the unit. Then I could tune it as you described. Sure wish there was a way
of seeing whether they are putting out a signal or not.
There isn’t much to the circuit boards so I was thinking of trying to find a way of
repairing the two spares. But, I see replacements remotes from Heddolf are only about
twenty bucks so I’ll probably just buy a couple of new ones to keep as spares and pitch
the old ones.

That makes sense Scott, soon as I get settled in to the new place I’ll replace the coax.
Problem might be finding the fittings for the ends, not sure if they are standard coax
connectors. Any idea what impedance I should look for or does it make any difference for
a receiver?? Also where I might get five or six feet of it, I don‘t need a whole roll?? The
cable that’s on there is a small diameter, about 3/16” whether that helps at all and it‘s
been painted several times so there isn‘t any way see what was printed on the jacket.

Denny G

Is the receiver box earth grounded in any way?

That I would have to take a look at John, the gate is at the new place and I'm at the old place. I believe the receiver is housed in a plastic case. In what way would that effect it??
Been looking for "how these work" and haven't been able to find any information. I'm assumng that the receiver operates a relay which switches the motor (looks like 1/4-1/3 hp) on and or reverses it.

DG

I serviced garage door openers for over 35 years, never saw a UHF receiver with ground.. All the external receivers were powered by 24v in series with a trigger relay and mounted in a plastic housing... Older models didn't even have a antenna and would work at 250ft plus(well they did but we removed them for being over sensitive, they were later deleted from factory)... Newer types have the receiver mounted inside the opener head, with a wire hanging out as antenna...

In the old days we used a tuning meter to rough set the transmitters that was just a variable cap with a pointer knob that could tune from 290-400Mhz, if necessary was recalibrated from a fresh transmitter(IE pointer knob fell off), once close the Tx were then tuned to the receivers that were not supposed to be re-tuned... With the introduction of digital controls Chamberlain(Sears supplier) set everything to 390Mhz, but we could order 315Mhz for high interference areas... That included those who lived in the shadows of the local TV transmitters, seems a harmonic from Ch 10 would render 390Mhz useless...

Most of today's automotive remotes are also around 315Mhz...

Tom

Thanks for the comeback Tom. I believe the receiver installed is older technology. Appears that ESP Micom was
made by Intercontenental Dynamics Corp who is out of it, it became Heddolf which is now Keystone. I haven't
found a source for the 315 MHz recerivers anywhere on the network. Good thing I've got a new spare receiver in
the box that came from IDC, in Broadview, IL.
When I get a few minutes I'm gonna take the antenna out and give it a good looking over.

Denny Graham
Sandwich, IL

Make sure to check the battery in the remote. Cooler weather could effect the battery.
Dan

Hello Tom,
The problem my folks have living near the navalship yard is that testing the radar causes the garage and car alarm remotes not to work during testing .
The local paper had a article on it The goverment Said they will not change freq the people have to either replace the units or live with it.
man I say the navy should change not us tax payers why should you half to toss out a good garage door opener because the goverment is stuborn

Because they have the power to destroy you.
Dan

Yeah I had a same issue some time back with openers near the Norfolk Naval Shipyard... We took probably 10 calls for no transmitter operation in old South Norfolk(section of Chesapeake) and Craddock section of Portsmouth... Not one were malfunctioning the next day when we ran the calls...

All those were on the still current 390Mhz freq, so if same incident occurred today with a new unit, I'd bet it still would not function...



Do what???? Every Sears model since '82 has electronic safety and will reverse if the door hits something(prior units used a mechanical system that worked fine also)... True if some yahoo maladjusted the controls they could do damage but otherwise are safe(every opener should be tested at approx six month intervals)... I have a '83 & mom has a '80 mechanical system still in use with no plans to retire them --- ever... Most parts are obsolete but I have a hoard(including two NOS units) that will out last me...

After things dried out last night, I spent a few minutes going over the antenna and found
that under the bracket there appears to have been some sort of insulator. That was
apparently missing so for the time being till I can find another antenna, I’ve wrapped the
whole base in rubber tape and covered that with friction tape then a layer of electrical
tape. Now we’ll see what happens when it rains the rest of the week.
Thanks for the comments guys, I appreciate it.

Denny Graham
Sandwich, IL

Denny- testing the seemingly nonfunctional units should be fairly easy. Find someone, probably a nearby ham, who has a frequency counter that's good to 500MHz. He'll need a working unit for comparison and the two bad ones. I have a spectrum analyzer that belongs to my company and could check them that way, but you'd have to send them to me since I'm a long day's drive from you.

As for the coax, it's probably 75 ohm, but I couldn't tell you what the type number is. Perhaps a more knowledgeable ham in your area could help there too.

Scott Todd