Antennae Booster

Assuming that they're both DC supplies, and assuming that you get the polarity correct (positive-supply to positive-load, negative-supply to negative-load), and assuming that you're careful to not turn the variable power supply up to higher than 6 volts... yes, it should work. The 300 mA capacity of the variable supply is greater than the

100 mA which the booster will draw, and that's OK. However, turning up the supply to above 6 volts may damage the booster. I'd recommend checking the supply voltage with a voltmeter before you connect it to the booster.

Do be aware that "antenna booster" amplifiers can cause more problems than they solve. In most cases you'll get better results by improving your antenna setup.

OK, very good. Thanks for that advice.

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** Unless you need to run multiple co-ax lines from your antenna, such boosters are a useless scam.

I could only laugh at folk I saw buying them to *fix* the lousy pic that was coming from an indoor antenna in analogue days - and scowl at the ignorant pigs who supplied them for that purpose.

This are not different now.

..... Phil

I agree with Dave.

It does not matter what the current rating of a supply ( as long as it is equal to or greater than what is needed by the device) is if it puts out the required voltage and not more.

Some wall cubes will be listed at one voltage, but with a much lighter load will put out much more voltage.

Just think of a voltage regulated supply like your house wiring. Many circuits are either 15 or 20 amps, but supply less than a tenth of an amp that many wall cubes and night lights use. Even the newer LED light bulbs only pull slightly more current than that.

A device that is working properly will only draw the ammount of current needed.

Agreed on all points except that, in certain situations, using an antenna booster is the only way to get an acceptable reception.

TV came to this remote corner of India in 1980 when some army people discovered that it was possible to receive stations in neighbouring Bangladesh. Due to the very hilly terrain, reception varied from fair to unusable within tens of meters, all with outdoor yagi antennas. Antenna boosters were a must.

The boosters were all alike, made up of 4 or 5 bjt amplifier stages. Power was fed to the booster via twin 300-ohm cable from an indoor 12V AC supply and gain was adjusted by means of a series potentiometer.

I was the local "expert" and I experimented with different antenna types, including yagi arrays and helical antennas with a

6-foot plane reflector. Some people claimed that reception was noticeably improved by hanging aluminium pans on their yagis.

Once I even rigged up a passive re-radiator with a back-to-back pair of yagis on a hilltop for a client who had no reception at all in his house which was located on the blind side of the hill. It worked somewhat but was not really satisfactory.

What I couldn't really explain was that reception slowly but steadily degraded in the decade from 1980 to 1990 (when cable TV arrived). In 1980, I could often get excellent reception in my house with literally an aluminium coat hanger plugged into the antenna socket. By contrast, I could watch the 1990 FIFA World Cup only with an array of four yagis *and* an antenna booster.

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** You are describing a dedicated "mast head amplifier" which do work well with weak signals.

"Antenna boosters" are not the same thing, only meant for indoor use.

.... Phil

I'm familiar with the term 'masthead amplifier' but they're all called 'antenna boosters' over here - in popular usage, on the package and sometimes on the unit itself. I didn't know that the latter term is reserved for indoor units elsewhere.

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** Did I hear someone say "antennae booster" ??

.... Phil

masthead amplifiers generally need a power injector which might have coax i n coax out and a port for power. The amp is on the mast.

Other amplifiers may just need a power source and are not remotely mounted.

I'm currently using a channel master CM-7777 at the mast with an 18db amp i n the attic with an attenuator, so 0-18db. i think the CM-7777 is defectiv e. For distribution to about 12 locations I was using a 30-45db amplifier until it went south. Currently distributing the signal to two locations.

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ell with weak signals.

** I have Indian neighbours from Hyderabad - he's an IT expert and she a st ay at home mom.

I soon discovered "Indian English" differs from mine in numerous way - we r egularly wind up speaking at cross purposes cos they apply different meanin gs to everyday words. She also spends hours each day staring at her I-phone so picks up lots of Americanisms.

For instance - they had no idea what Styrofoam was cos their name for it is "Thermocol". It's hard for them to believe their English is actually a bit odd as they only socialise with other Indians.

.... Phil

Indian English is a recognised variety of English. Not even definitely a dialect, as it has its own grammar in some cases, which can be argued to make it a distinct language (as e.g. Schweizerdeutsch is a distinct language, not merely a dialect of German).

CH

In cellular service, it's called a TMA (tower mounted amplifier):

If the downlink is via RF instead of coaxial cable, it might be considered an "active repeater": There is also a "passive repeater" which functions in the same manner using two antennas, but lacks a powered amplifier. If the downlink coax cable or RF path operates on a different channel than the receive signal, it's a "TV translator".

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Masthead amps make good targets for lightning hits. I've seen a few where every semiconductor in the amp was fried.

The CM-7778 has 16dB gain: while the CM-7777 has 26dB gain: Also see the CM-7777HD (adjustable gain) and the CM-7778HD (distribution amp).

This might help: "CM-7777, CM-7778 Titan 2 & CM-7778HD detailed troubleshooting."

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

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a stay at home mom.

we regularly wind up speaking at cross purposes cos they apply different me anings to everyday words. She also spends hours each day staring at her I-p hone so picks up lots of Americanisms.

t is "Thermocol". It's hard for them to believe their English is actually a bit odd as they only socialise with other Indians.

** Sure - as typically spoken in India, you see it on TV, movies etc.

But educated folk, living outside India for many years lose most of those i diosyncrasies. Tricks you into thinking they have left them behind.

Conversations with them are fun but always fairly short. You soon run into a language /cultural dead end. Big shame.

..... Phil

Two peoples separated by a common language.

George Bernard Shaw

Yeah... probably need to consider them to be a potentially-sacrificial component.

The really troublesome ones I've heard/read about, are the cheapies... sometimes using just a single broadband transistor as a gain element. Some of these have been known to break into oscillation, for some reason (or no reason) and blast broadband noise all over the place.

talks about one such case, in which several on-shipboard "active TV antenna" systems were emitting enough RF crud to blank out GPS reception in the harbor in Moss Landing, CA. Not a good thing to lose your GPS when you're trying to come into a foggy harbor at night.

This is one reason why which buying a well-tested, professional-grade mast-head amplifier would probably be a better idea than buying a generic cheapie.

I had one mounted on a redwood tree. It wasn't hit by lightning. Instead, it was invaded by ants, dripping formic acid, which ate the copper traces on the PCB. I was prepared to replace all the active components, but not the entire amplifier.

This might fill in a few details: Note the photo of the antenna. The cloverleaf pattern is NOT a broadband device and will not present a 75 ohm impedance to the amplifier input. Designing a broadband amplifier to be unconditionally stable and provide a low NF (noise figure) as well as high gain into such an antenna is difficult. There will be some frequency, where the antenna presents the perfect impedance to cause the amplifier to oscillate. Also, such an antenna construction is not very tolerant of the corrosive effects of a marine environment and probably should have been potted or conformal coated.

Yep. That happened near me. Although I knew some of the participants, I didn't know that there had been a transmitter hunt until two years after it was over and the article appeared in GSP World.

GPS selective availability was finally turned off on May 1, 2000, navigating a 150 ft wide harbor entrance channel by GPS would have been theoretically possible. At the time, MBARI did operate their own DGPS transmitter on Mt Toro, but that was for precision vessel and buoy location in the bay. Today, even with WAAS, GALILEO and GLONAS satellites added to improve GPS precision, I'm told it's still tricky due to reflections from moving metal masts and rigging, plus a very large steel building at the power plant. Once into the channel, I would probably switch to navigating by the harbor lights:

Yep. In my never humble opinion, there was probably nothing wrong with the amplifier. Instead, it was the design of the antenna, which had the misfortune of not being properly matched to the RF amplifier causing the amp to oscillate. A properly designed Yagi, Bow-Tie, LPDA (log periodic dipole array), or other broadband design, would worked better, and not oscillated.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

that requires a power supply of 6v 100ma, can i use a variable power supply 6v 300ma???

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My idea of a "booster" or "signal amp" is a bigger/higher gain antenna.

As far as language differences are concerned, England and India are forever bound by their use of English. Compared to them, what is spoken in the States is called AMERICAN: a rebellious corruption and bastardisation of what is spoken/written in the two aforementioned nations.

Where else do you hear "nucular" routinely substitute for nuclear? Or plural's of item's succeeded with an apostrphe s? LOL!