Increasing the range/output power of a UHF video sender?

I have a UHF audio-video sender unit which I am attempting to use in a house with three floors, in a remote area. The aim being to send the signal from a VCR downstairs in order that a couple of TVs on the upper floors can receive it.

Thsi is the device I bought:

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In actual fact it is smaller than it appears - about half to three quarters the size of a VHS cassette.

Anyway, it works surprisingly well on the whole, but the signal does not reach the uppermost floor with enough gain. So I'd like to amplify it a bit more (no more then 50% I suppose), or otherwise increase the range.

So far I can see two potential ways:

1- use a larger aerial than the small telescopic rod antenna fitted. (not sure if the sender's o/p electronics would be up to the job though)
  1. Connect an amplifier in series between the output of the sender and it's antenna.

There may be simpler ways; I'm all ears.

In regard to (2.), I was thinking of adapting a TV signal booster amplifier with a 20% variable gain I have lying about. Not sure at what part of the sender's circuit I would need to attach it though (I don't have the schematic). Presumably it would have some effect if I connected the sender's rod antenna terminal to its input and then connected another antenna to its TV output jack .

Any thoughts? Thanks

-B

Reply to
b
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We need more information. What channel are you using? What's the size of the transmitter's antenna?

Transmitters of this sort often have a short antenna (and even resistive padding ahead of the antenna) to limit the output.

Lengthening the antenna might provide a stronger signal, but there's no guarantee. You need to calculate the length (half- or quarter-wave) for that channel.

Reply to
William Sommerwerck

b wrote in news:9d6330dc-4331-4e1a-8615- snipped-for-privacy@g28g2000yqh.googlegroups.com:

You have an unlicensed transmitter that operates under specific rules designed to prevent excessive signal strength causing interference to licensed services.

Anything which might result in a stronger transmitted signal might violate the regulations under which such devices operate and might cause interference to vital communications. Better to use cables and avoid radiating a signal.

There may be fines and legal liability associated with damages caused by such a transmitter outside of the permitted limits.

--
bz    	73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an 
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Reply to
bz

the

hat

It's output is currently UHF ch.34 (I'm in Europe),antenna length is no more than 2 feet extended, if that.

-B

Reply to
b

Optimum 1/4 wavelength antenna is 4.7 inches at 580 Mhz. In any case the antenna should not be more than twice that long.

greg

Reply to
GregS

First, try aiming the send and receive antennas. You want the rod parallel to the ground for best vertical range.

Second, consider a high gain antenna; half your signal goes into the ground when you aim 'up' with this kind of whip/dipole antenna. Antennas with gain (even just 5 dB) are relatively easy to construct; ask at a good library for the ARRL Antenna Book for ideas.

Reply to
whit3rd

Thanks for the responses. I have tried moving the antennas, but little change.Will try vertical. By antennas with gain, are you referring to the physical structure or to some kind of amplification circuit? If the latter, I might be able to convert the signal booseter unit I have.

I will take Greg's advice and ensure the length is not excessive on the existing antenna.

I have also picked up a Unaohm ep- 742 field strength meter, will check the levels.

-B

Reply to
b

It's the antenna shape and all the nearby grounded or reflective elements that creates 'antenna gain'. A metal-sheet reflector, for instance, one half wavelength parallel to your whip antenna, can give 3 dB of gain. This is the result of directing the antenna output power, not of increasing it, but the effect at the receiver is just like a higher power output.

Reply to
whit3rd

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