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uk.tech.digital-tv (Digital TV - General) (uk.tech.digital-tv) Discussion of all matters technical in origin related to the reception of digital television transmissions, be they via satellite, terrestrial or cable. Advertising is forbidden, with no exceptions.

Signal Drop



 
 
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  #1  
Old September 25th 13, 10:27 AM posted to uk.tech.digital-tv
Pinnerite[_2_]
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Posts: 94
Default Signal Drop

Following the recent messages to re-tune for Film4, I found that my two
computers with TV cards could hardly recover many channels following a scan.
I switched wall sockets as some had hitherto given better results. No
difference.

The only common feature is a 1970s Labgear distribution amplifier in my
loft. Its power indicator lamp is still on but its UHF transistor might have
been kicked out by a lightening surge.

Without a means of testing it, it looks like I will need a replacement.
Can anyone recommend something offering decent gain and 16 outlet sockets?


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  #2  
Old September 25th 13, 02:23 PM posted to uk.tech.digital-tv
Bill Wright[_2_]
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Posts: 9,381
Default Signal Drop

Pinnerite wrote:
Following the recent messages to re-tune for Film4, I found that my two
computers with TV cards could hardly recover many channels following a scan.
I switched wall sockets as some had hitherto given better results. No
difference.

The only common feature is a 1970s Labgear distribution amplifier in my
loft. Its power indicator lamp is still on but its UHF transistor might have
been kicked out by a lightening surge.

Without a means of testing it, it looks like I will need a replacement.
Can anyone recommend something offering decent gain and 16 outlet sockets?


Why not temporarily bypass it to one of the feeds out? If that improves
matters the amp is ****ed. If the amp is the popular Labgear four way
one (CM6034DA I think) the gain to each output should be 8dB.

Bill
  #3  
Old September 25th 13, 09:07 PM posted to uk.tech.digital-tv
ian field
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Posts: 1,101
Default Signal Drop



"Pinnerite" wrote in message
...
Following the recent messages to re-tune for Film4, I found that my two
computers with TV cards could hardly recover many channels following a
scan.
I switched wall sockets as some had hitherto given better results. No
difference.

The only common feature is a 1970s Labgear distribution amplifier in my
loft. Its power indicator lamp is still on but its UHF transistor might
have
been kicked out by a lightening surge.

Without a means of testing it, it looks like I will need a replacement.
Can anyone recommend something offering decent gain and 16 outlet sockets?


I'd use something cheap & nasty as a sacrificial "front-end" followed by a
good quality splitter.

  #4  
Old September 25th 13, 11:40 PM posted to uk.tech.digital-tv
Bill Wright[_2_]
external usenet poster
 
Posts: 9,381
Default Signal Drop

Ian Field wrote:


"Pinnerite" wrote in message
...
Following the recent messages to re-tune for Film4, I found that my two
computers with TV cards could hardly recover many channels following a
scan.
I switched wall sockets as some had hitherto given better results. No
difference.

The only common feature is a 1970s Labgear distribution amplifier in my
loft.

Is there not an aerial?

Its power indicator lamp is still on but its UHF transistor
might have
been kicked out by a lightening surge.

Without a means of testing it, it looks like I will need a replacement.
Can anyone recommend something offering decent gain and 16 outlet
sockets?


I'd use something cheap & nasty as a sacrificial "front-end" followed by
a good quality splitter.

The problem is that without knowing the incoming signal levels and the
cable losses we cannot possibly know how much gain is needed. Without
going more than two miles from here I could take you to a house where
the aerial terminals have +20dBmV on all muxes, and one where the figure
is -15dBmV. And a house where some of the downleads are 30m and one
where they are all less than 10m.
In my opinion the most we can legitimately advise without proper
information is to try bypassing the amp. Suppose we advise him to fit a
+30dB amp followed by a -16dB splitter. The signal levels then presented
to the receivers could be fine, or they could grossly overload it.
I don't think we should advise the use of cheap & nasty amplifiers.
These are easily overloaded and can be very noisy, often providing
apparently healthy signal levels but with a poor BER.

Bill
  #5  
Old September 26th 13, 06:40 PM posted to uk.tech.digital-tv
Pinnerite[_2_]
external usenet poster
 
Posts: 94
Default Signal Drop

Bill Wright wrote:

Pinnerite wrote:
Following the recent messages to re-tune for Film4, I found that my two
computers with TV cards could hardly recover many channels following a
scan. I switched wall sockets as some had hitherto given better results.
No difference.

The only common feature is a 1970s Labgear distribution amplifier in my
loft. Its power indicator lamp is still on but its UHF transistor might
have been kicked out by a lightening surge.

Without a means of testing it, it looks like I will need a replacement.
Can anyone recommend something offering decent gain and 16 outlet
sockets?


Why not temporarily bypass it to one of the feeds out? If that improves
matters the amp is ****ed. If the amp is the popular Labgear four way
one (CM6034DA I think) the gain to each output should be 8dB.

Bill


I remembered that I had a small UHF preamp purchased for a project some
years ago. I connected it to each active down lead and re-tuned the devices
one by one. That solved the initial problem. Rather than be pressured to
repair the Labgear CM7073 bought over 30 years ago, I've ordered a cheapo
giving slightly higher output gain on each output (10db) compared with 8db
from the Labgear. I will not be able to try it until the end of October
though.

Alan



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