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Old 11th Aug 2019, 4:22 pm   #1
Max Ripple
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Default Vintage satellite TV, weird or what?

Clearing out some old papers, I was reminded of a time back in the eighties, when we were installing satellite TV systems.

We had installed a 90cm "dish" in the valley of the roof of a local hotel, to allow the owners to view Spanish TV both in their quarters and in the lounge of the restaurant. It was very popular too.

In those days we used Precision Antenna dishes which were very well made locally. They were parabolic dishes with alloy waveguides which you could adapt for different configurations. We either used Chapparal electro/mechanical, or Irte electromagnetic polarisers. Each job was slightly different and thus interesting.

Responding to a service call from the hotel one day I found that only a snowy (analogue of course then!) picture was obtainable.

My initial fear was that the expensive LNB had failed,so I climbed up onto the roof to investigate and connected my trusty Maspro RF meter (recently donated to a member here) to the LNB and sure enough low signal.

It was common in those days to find that spiders had colonised the waveguide, as it was a warm n cosy area, but they hadn't made a home here yet.

Before changing the LNB I spotted something at t'other end of the waveguide ,which upon closer inspection turned out to be a piece of cheese!

After removing this, the signal came back up to normal strength ,hooray!

Who knew that cheese was impervious to microwaves? Do different cheeses affect different frequencies? How had the cheese got there?

With the benefit of hindsight of course, I imagine that a bird probably dropped the piece of cheese and due to the shape of the dish, the piece had bounced into the throat of the waveguide?

I climbed down the ladder and was rewarded with a great picture, but no offer of dinner or a nice drink, hey ho.

Happy day's though!
Does anyone else have any satellite tv stories from those day's
Nick
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Old 11th Aug 2019, 4:27 pm   #2
ms660
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Default Re: Vintage satellite tv,weird or what?

E-dam ?

Lawrence.
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Old 12th Aug 2019, 11:26 am   #3
G8HQP Dave
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Default Re: Vintage satellite TV, weird or what?

Cheese contains salty water, which is a poor conductor so ideal for absorbing microwaves. Most foodstuffs are good microwave absorbers, which is why most of us have a microwave oven in our kitchens.
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Old 12th Aug 2019, 11:34 am   #4
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Default Re: Vintage satellite TV, weird or what?

Cheese also contains a lot of fat, which absorbs microwaves well.
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Old 12th Aug 2019, 12:18 pm   #5
ms660
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Default Re: Vintage satellite TV, weird or what?

In the early days I once installed a satellite dish (one of the old large ones) on the roof of a detached Khazi in the customers garden... Beam me up Scottie...

Lawrence.
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Old 12th Aug 2019, 12:44 pm   #6
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Default Re: Vintage satellite TV, weird or what?

No cheese Nick, but I shudder when I recall our 'adventures' with the whiz-bang Echostar 4500 receiver/positioner. We'd just started installing these things when a trickle of complaints started coming in. The receivers seemed to be forgetting the channel/polarity settings and sometimes ignoring the first channel digit from the remote control.
Muggins here was despatched to find out what was going on. After a reset and re-tune, all seemed well and there was never any sign of the 'missing digit'.
The complaints kept coming in, so I brought one into the workshop and put it on soak test with our dish.
Sure enough, the receiver would occasionally ignore the leading digit of the channel number and go searching for it (and turning the dish) in vain. It seemed to happen after there had been no remote activity for a while.
The next day at switch-on, all memorised channels had gone and needed inputting again from scratch.
Our customers were not happy and neither was my boss, who seemed convinced I was setting the equipment up wrong. Eventually I persuaded him to take a receiver to the supplier and explain the problem. They happily put it on soak for a few days but said they could find no fault. So boss goes to collect it and asks the service guy to try channel 101 (or whatever) and lo & behold the receiver sees only '01' and goes into a sulk. Service guy tries to say he must have missed the initial '1' key, but boss isn't having it and insists the RX is sent back to base for further investigation.
A few days later we get a phone call from Technical, telling us that the receiver is from a batch that was fitted with a faulty ROM and should have been sent back by our supplier.
So all our installed receivers were collected bundled up and delivered to our supplier with a stiff note demanding new ones. No further trouble after that, in fact they were damn fine receivers.
It was a horrible time, with me getting it in the neck from both sides. I'd been with the firm for 20 years, but this business was enough to set me on a search for something else.
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Old 12th Aug 2019, 3:45 pm   #7
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Default Re: Vintage satellite TV, weird or what?

You're not the first to have animal-related microwave attenuation issues; AT&T have had it too - see this article in National Geographic.

https://www.nationalgeographic.com/n...er-california/

[Rattlesnakes taking up residence in roadside cable-TV cabinets are also relatively common in the southern US]
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Old 12th Aug 2019, 4:52 pm   #8
Max Ripple
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Talking Re: Vintage satellite TV, weird or what?

Well,the biggest critter I encountered was a very territorial seagull in St Ives.
It didn't take kindly to us trying to assemble a dish on the roof of a guest house,which we assumed was "it's"!!!!

No snakes happily,but some "slippery" customer's sometimes!!!
The EchoStar reference remind's me that their receiver's did tend to be idiosyncratic at the best of times.Super build of course,but just too many "bells n whistles".

I think that many manufacturers were winging it,and letting us installers find out the problems for them.Certainly,most of the kit was'nt designed allowing for our weather!!! Water ingress was probably the most common failing in outdoor equipment.
Challenging but interesting times for a techie.
Happily,we had an agreed policy to avoid "the man in the shop said" problems.
If he sold a system without a site survey(remember those?)he would be required to accompany us on the install and possibly share the sensation when the odure hit the fan.
Nowaday's anyone with a modicum of wit can install satellite tv it seems,using a wet finger and luck,and some do of course!
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