[TenTec] Low Pass Filter

[DAVID HELLER]

Some of the high-pass filters on and off the market can be a bit flaky. 
from  your description the problem is in no way from your set. Are there any 
near-by medium frequency broadcast transmitters?  If so, any effect from 
them on the telly?  I would advise trying a Drake high-pass TV filter flush 
against the tuner and well grounded.  Our experience has been the Drake 
jobbie is definitely as good as any other we've tried and far superior to 
most.  Dave, K3TX
----- Original Message ----- 
From: "Doug Turnbull" <turnbull at net1.ie>
To: <tentec at contesting.com>
Sent: Tuesday, May 20, 2008 6:00 PM
Subject: [TenTec] Low Pass Filter


> Hi All,
>
> I take the point that if one local TV is not being interfered with on any 
> of
> the channels that the transmitter is not at fault.   At the moment I am
> suffering from TVI on the 160 Meter band only.   Though there is no trace 
> of
> interference on any signal  or on any TV in our QTH there is a problem 
> with
> a neighbour.   The problem at the neighbours happens only with terrestrial
> signals from a transmitter north of Belfast seventy miles distant.   I 
> have
> to tread carefully as my neighbour is a friend and his good wife has
> advanced MS so TV is one of her few pleasures.   Some of the HPF seem to 
> be
> of little help as for some reason some indicate a lower rejection limit of 
> 5
> MHz.   Why I can not imagine.   I have ordered some HPFs from Industrial
> Communications Engineers (ICE) of Indianapolis and these may help with the
> neighbour.   Sadly ICE build to order and are slow in filling orders.
> There are no HPFs used in our QTH but I hope this is the solution for our
> good neighbour.  Ferrites and braid breakers have not helped.
>
> As to the LPF I use an ICE filter but it does not seem to make any
> difference in my case.   Still I keep it as additional insurance. 
> However
> there is a point from the ICE LPF manual which I would like to share.
> "Because the filter's job is to eliminate these higher frequencies it 
> should
> be kept in mind that the wavelengths of signals the filter is designed to
> attenuate are very short.   Thus, long ground leads from the filter body 
> to
> earth ground lessen the filter performance somewhat.
>
> In order to get the best performance from your filter try to keep the
> connecting lead length from the filter body to the *** point at which the
> ground rod actually touches the ground as short as possible."    ICE
> recommend mounting the filter just above the ground rod.   My shack is on
> the second floor so perhaps I will mount my filter outside in a plastic 
> box
> in immediate contact with the ground rod.   The main coax will then drop 
> to
> this filter and the ground rod before proceeding from the filter to the
> external antenna selector.   There are problems for hams operating above
> ground level.   Again I accept that my problem is likely one of 
> overloading
> my neighbour's TV.   This problem still manifests itself while running 100 
> W
> output though 400 W output does not upset my own sets on the most marginal
> of signals.
>
> This reflector has been a great help and interest to me and I thank all of
> you for this.   I love my O2 and look forward to improvements from the
> mother ship.   In time I will purchase the O3 but I hope this is a few 
> years
> off and that TenTec provides additional improvements.  Greed is not always 
> a
> bad thing.     73 Doug EI2CN
>
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