J
Joerg
- Jan 1, 1970
- 0
Frank said:Frank said:Phil Allison wrote:[lot of snip]** What the **** does that mean ?But what really miffed me was this: Placed the antenna on a mast after
re-roofing the house. So, I equipped it with a nice preamp, splitter,
postamps with eight outputs .....** And then this ASS blames his TV set's tuner for the bad outcome.Pathetic really........ PhilI presume you meant to say that the performance of most preamps would
limit linearity, and would dominate IP3, etc. over the tuner. That's
true, although I've seen some that don't ... I've designed some that
don't; maybe Joerg used a commercial model.
Well, yeah. If a lab grade receiver works just fine and the TV on the
same antenna is turning into a hopeless pile of intermodulation it's
pretty clear that the TV isn't up to snuff. Which didn't surprise me. I
just didn't expect it to be this bad.
Agreed. Did you do any tests on the TV tuner? IP2, 2-tone IM, etc.?
Did it use a solid state tuner or a "can"?
I did back in the 90's. Shook my heard and discarded the tuners
afterwards, then cracked out a Mini-Circuits DBM to build the receiver.
In the 80's they were better but there I used tuners scrapped out of
older TVs. Probably the older engineers still knew how to do it. One had
Ge-Transistors (AF239?) and was, well, somewhat ok. The other one had
two tubes and was quite excellent.
And sure enough the TV where that tube tuner came out of was the best
(until it's flyback XFMR went up in a plume of smoke one fine day). When
a powerful pager system was installed near our home almost all "modern"
transistorized TVs fell off the rocker. This signal was even
out-of-band, BTW. Telecom came out with lots of expensive Rhode&Schwarz
gear, determined that poor tuner design was to blame so they were not
legally obliged to do anything about it yada, yada, yada.... Lots of
negative PR mounted and then they agreed to supply notch filters for
free. I mounted a lot of these for neighbors because installation was
not included.
Besides the transistor versus tube thing there was another major
difference: The tube tuner had a ganged variable capacitor while the
transistor version used varicap diodes. I did not investigate the tuners
in our current sets. Not really worth it. Not just because of lousy RF
performance but except for an occasional old movie and the evening news
there ain't much to watch anyhow.
Even the old tuners were "in a can", except that those cans were the
size of a small paperback book. Very nicely done. For example, they had
thin copper foil on a rubber cushion to make sure that the lid was
RF-tight. They don't make'em like that anymore :-(