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

B

b

Guest
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:
http://www.wakamatsu.vc/cgi-bin/pc/data/1-660829b.jpg

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)
2. 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
 
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.
 
b <reverend_rogers@yahoo.com> wrote in news:9d6330dc-4331-4e1a-8615-
d08ebe47c52e@g28g2000yqh.googlegroups.com:

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:
http://www.wakamatsu.vc/cgi-bin/pc/data/1-660829b.jpg

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)
2. 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
Click to expand...
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
infinite set.
 
In article <7c57238d-73d1-41b6-a198-f018c4dcb2e9@k17g2000yqb.googlegroups.com>, b <reverend_rogers@yahoo.com> wrote:
On Mar 8, 4:05=A0pm, "William Sommerwerck" <grizzledgee...@comcast.net
wrote:
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 t=
hat
channel.

It's output is currently UHF ch.34 (I'm in Europe),antenna length is
no more than 2 feet extended, if that.
-B
Click to expand...
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
 
On Mar 8, 4:05 pm, "William Sommerwerck" <grizzledgee...@comcast.net>
wrote:
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.
Click to expand...
It's output is currently UHF ch.34 (I'm in Europe),antenna length is
no more than 2 feet extended, if that.
-B
 
On Mar 8, 6:41 am, b <reverend_rog...@yahoo.com> wrote:
I have a UHF audio-video sender unit which I am attempting to use in a
house with three floors, ... but the signal does
not reach the uppermost floor with enough gain.
Click to expand...
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.
 
On Mar 10, 10:29 pm, whit3rd <whit...@gmail.com> wrote:
On Mar 8, 6:41 am, b <reverend_rog...@yahoo.com> wrote:

I have a UHF audio-video sender unit which I am attempting to use in a
house with three floors, ... but the signal does
not reach the uppermost floor with enough gain.

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.
Click to expand...
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
 
On Mar 10, 5:03 pm, b <reverend_rog...@yahoo.com> wrote:

By antennas with gain, are you referring to the physical structure or
to some kind of amplification circuit?
Click to expand...
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.
 
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