Dummy load on unused masthead outputs?
 

I will be installing a 4 output masthead amp in the coming weeks and
although I will be using all 4 outputs at some point I will only be using 2
to start with. Should I put 75ohm dummy loads on the initially unused
outputs?

thanks

Gav

Dummy load on unused masthead outputs?
 

On Jan 12, 10:09*am, "Gav" wrote:
I will be installing a 4 output masthead amp in the coming weeks and
although I will be using all 4 outputs at some point I will only be using 2
to start with. Should I put 75ohm dummy loads on the initially unused
outputs?

thanks

Gav

Most amps don't need this.

Bill

Dummy load on unused masthead outputs?
 

Dummy load on unused masthead outputs?
 

"Gav" wrote in message ...
I will be installing a 4 output masthead amp in the coming weeks and although I will be using all 4 outputs at some point I will
only be using 2 to start with. Should I put 75ohm dummy loads on the initially unused outputs?

thanks

Gav

These ancient things were supplied with one 75R Belling Lee
terminator for the unpadded output only.
http://tinypic.com/r/mtunax/6

--
Graham.

%Profound_observation%

Dummy load on unused masthead outputs?
 

On Jan 12, 5:02*pm, Terry Casey wrote:
wrote:
On Jan 12, 10:09 am, "Gav" wrote:
I will be installing a 4 output masthead amp in the coming weeks and
although I will be using all 4 outputs at some point I will only be using 2
to start with. Should I put 75ohm dummy loads on the initially unused
outputs?

thanks

Gav

Most amps don't need this.

Bill

It is, however, good practice and to be commended ...

Terry

Well, if Andy Wade was here he'd tell you that with his products the
way the outputs are derived means that the load on any of them has
little or no effect on either the behaviour of the actual amplifier or
the signal available at the other outputs. I usually have the
analyser with me when I install a multi-output amp, and after I've
tested all the outputs the test lead is usually left plugged into one
port (for no good reason; it just is). As I connect the other outputs
I see very little perturbation on the analyser screen.

The days of resistive star networks are long gone! I do remember a
certain product from the 1970s that would go completely mad if the
majority of the outputs weren't terminated, although to be honest that
product would sometimes go completely mad when they were anyway.

There was also a one-in one-out 12dB amp that would not feed into a
single channel filter, presumably because on all frequencies except
the one the filter accepted the signal was bouncing back. The same amp
was a bit dodgy when it was used to feed a VCR and TV set (looped),
with the signals available to the TV set varying dependent on the
channel the VCR was tuned to.

By gum there's been some dodgy gear sold over the years! Group B
aerials that don't work above channel 50, Group A aerials that don't
work above channel 32 or below channel 23, coax with the inner running
along one of the spaces in the dielectric, coax plugs with grub screws
that cause dead shorts, wall brackets with such bad welding only the
paint holds them together, alloy masts with a seam that splits open
and turns the mast into sort of twirly thing, wallplates that can't be
connected without the coax shorting them out, wallplates that have
losses varying from 2 to 18dB at random with frequency, wallplates
that short out on the backbox! I could go on!

Bill

Dummy load on unused masthead outputs?
 

"Graham." wrote in message
...


"Gav" wrote in message
...
I will be installing a 4 output masthead amp in the coming weeks and
although I will be using all 4 outputs at some point I will only be using
2 to start with. Should I put 75ohm dummy loads on the initially unused
outputs?

thanks

Gav

These ancient things were supplied with one 75R Belling Lee
terminator for the unpadded output only.
http://tinypic.com/r/mtunax/6


I've got an SLX8 in my loft which requires a terminator in the full (20db
AFAICR) output. The other 8 outputs don't matter, I've only got 6 downleads
running from it.

Dummy load on unused masthead outputs?
 

Terry Casey wrote:
wrote:
On Jan 12, 10:09 am, "Gav" wrote:
I will be installing a 4 output masthead amp in the coming weeks and
although I will be using all 4 outputs at some point I will only be
using 2
to start with. Should I put 75ohm dummy loads on the initially unused
outputs?

thanks

Gav

Most amps don't need this.

Bill

It is, however, good practice and to be commended ...

Terry

Nothing in RF is 100% isolated, it is always measured in ratios (ie dB).

There will be an effect, but it might not be measurable by installers
equipment. But do bear in mind that STBs will also work on signals that
the equipment probably can't measure (even if its says it can).

I've used 20dB amps for signal distribution that failed when left
unconnected at the output. The connected figures for isolation were
very good and we didn't measure any difference in the other output
whether it was connected or not.

--
Tony