Hi,

I would like to reposition my 2M/70cm Vertical (Diamond X50) to a higher
position.

One option is to mount it above the TV aerial, I understand that the signal
radiation below the antenna is very small, does anyone have any experience
of a similar setup?

If so what kind of distances would you suggest between the antennae?

Obviously my main concern is TVI and poorer performance from the Diamond due
to its close proximity to the TV aerial.

I'm using RG-213 for the Diamond and normal coax for the TV.

Any help or suggestions would be appreciated.

Cheers,

Paul

Paul wrote:
Hi,

I would like to reposition my 2M/70cm Vertical (Diamond X50) to a higher
position.

One option is to mount it above the TV aerial, I understand that the signal
radiation below the antenna is very small, does anyone have any experience
of a similar setup?

If so what kind of distances would you suggest between the antennae?

Obviously my main concern is TVI and poorer performance from the Diamond due
to its close proximity to the TV aerial.

I'm using RG-213 for the Diamond and normal coax for the TV.

Any help or suggestions would be appreciated.

Cheers,

Paul


hey there. My sugesstion is the higher you can mount the vertical above
the tv antenna the better. Persinally I would mount the antenna a min.
of 3-5 feet above the TV antenna. Just rember that the higher the
antenna the more loss in the coax. I would also strongly suggest that if
you do mount the vertical above the TV antenna that you invest in some
TVI filters. I think radio shack or you local electronics part store
should have some in stock. ( They sould be fairly cheap. $3-$5 each or
something like that)

KD5JBK
Chauncey Baker
EM 15

I would like to reposition my 2M/70cm Vertical (Diamond X50) to a higher
position.

One option is to mount it above the TV aerial, I understand that the signal
radiation below the antenna is very small, does anyone have any experience
of a similar setup?

If so what kind of distances would you suggest between the antennae?

Obviously my main concern is TVI and poorer performance from the Diamond due
to its close proximity to the TV aerial.

hey there. My sugesstion is the higher you can mount the vertical above
the tv antenna the better. Persinally I would mount the antenna a min.
of 3-5 feet above the TV antenna. Just rember that the higher the
antenna the more loss in the coax.

Adding some form of choke balun, or some ferrite beads clamped onto
the outside of the coax, immediately below the antenna, might also be
a good idea. This will reduce the amount of RF which comes back down
the feedline and which might be coupled into the TV antenna.

I would also strongly suggest that if
you do mount the vertical above the TV antenna that you invest in some
TVI filters. I think radio shack or you local electronics part store
should have some in stock. ( They sould be fairly cheap. $3-$5 each or
something like that)

Standard TVI filters will probably not help matters much. The usual
television TVI filter is a high-pass filter, which will do an
effective job of keeping HF ( 30 MHz) out of the TV system and which
will probably have some effect on 6-meter signals as well. It will be
quite ineffective at keeping 2-meter signals out of the TV, since
these fall right in between the TV-VHF-low and TV-VHF-high bands and
are on the high-pass side of the filter's knee.

There are specialized band-stop which can be installed to "notch out"
the 2-meter signals. They're harder to find than ordinary low-pass
and high-pass filters. You may be able to find a cable-TV notch
filter which will do the job - if you can find one which is designed
to take out cable channels 17-19, that could help matters.

I had severe TVI problems at home due to 2-meter signals getting into
the TV antenna. The problems were noticeable on the TV in the den
(fed directly from the antenna via a splitter), and were very bad on
the several TVs and VCRs in the living room (fed via a cheap Radio
Shack distribution amplifier, which was no doubt being overloaded into
severe clipping and distortion due to the high RF levels).

The solution I ended up with is a CA7X-144/148 bandstop filter from
http://www.tinlee.com - it has a bandstop notch of better than 35 dB
between 144 and 148 MHz. Not cheap, but it seems well-built and has
cured the TVI problem when I key up one of my 2-meter rigs.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

On Tue, 24 Feb 2004 18:36:09 -0600, Chauney Baker
wrote:

Paul wrote:
Hi,

I would like to reposition my 2M/70cm Vertical (Diamond X50) to a higher
position.

One option is to mount it above the TV aerial, I understand that the signal
radiation below the antenna is very small, does anyone have any experience
of a similar setup?

If so what kind of distances would you suggest between the antennae?

Obviously my main concern is TVI and poorer performance from the Diamond due
to its close proximity to the TV aerial.

I'm using RG-213 for the Diamond and normal coax for the TV.

Any help or suggestions would be appreciated.

Cheers,

Paul


hey there. My sugesstion is the higher you can mount the vertical above
the tv antenna the better. Persinally I would mount the antenna a min.
of 3-5 feet above the TV antenna. Just rember that the higher the
antenna the more loss in the coax. I would also strongly suggest that if
you do mount the vertical above the TV antenna that you invest in some
TVI filters. I think radio shack or you local electronics part store
should have some in stock. ( They sould be fairly cheap. $3-$5 each or
something like that)

KD5JBK
Chauncey Baker
EM 15
I agree with the suggested spacing - just buy a 5 foot section and
you're set, it should 'telescope' right into the top of what you have.
You may wish to consider a lower loss coax as well, the 440 side will
appreciate you for upgrading to something like LMR400 at something
like half or 2/3 your loss with the RG-213.
Howard

Paul wrote:

I would like to reposition my 2M/70cm Vertical (Diamond X50) to a
higher position.

One option is to mount it above the TV aerial, I understand that the
signal radiation below the antenna is very small, does anyone have any
experience of a similar setup? ...

I've been set up like that for several years with an X510. It's mounted
on the top of the same mast as the TV antenna with the TV antenna about 3
ft below the X510. It's all mounted on my chimney about 25 ft up. I run
9913 inside the mast to the X510 (the X510's base fits nicely inside the
mast). The TV antenna is an el-cheapo Radio Shack (Tandy) unit fed with
RG-6 running down the outside of the mast. I have no problems with it
running up to 50W on 2M and about 35W on 70cm. There's no interaction
that I can see...no problems with TVI or anything...works quite well.
This is in the US...not sure if it would be different in the UK, perhaps
due to different TV freqs???

73... Mark AA7TA

Paul wrote:

Hi,

I would like to reposition my 2M/70cm Vertical (Diamond X50) to a higher
position.

One option is to mount it above the TV aerial, I understand that the signal
radiation below the antenna is very small, does anyone have any experience
of a similar setup?

If so what kind of distances would you suggest between the antennae?

Obviously my main concern is TVI and poorer performance from the Diamond due
to its close proximity to the TV aerial.

I'm using RG-213 for the Diamond and normal coax for the TV.

Any help or suggestions would be appreciated.

Cheers,

Paul


Are you in the UK or USA? Very different problems between the US VHF TV and
UK UHF TV. Advice which is excellent in the US just doesn't apply here. E.g.
we no longer have any VHF TV so VHF considerations are not applicable.

UK TV is ~ 470 - 615 MHz (Band IV) and 615 - 860 (Band V) so low Band IV
signals are quite close to 70 cms.

Best advice is to try it. If problems arise then there are some fairly simple
cures.

You might find
http://www.qsl.net/rsgb_emc/emcleaflets8.html
useful.

vy 73

Andy, M1EBV

(snip)
of 3-5 feet above the TV antenna. Just rember that the higher the
antenna the more loss in the coax. I would also strongly suggest that if
(snip)

KD5JBK
Chauncey Baker
EM 15

I do hope you meant to suggest that the longer the length of coax, the
greater loss, and not that actual height above the ground affects loss.

In other words, you're not saying that an antenna fed with 50 feet of coax
mounted at 10 feet has less loss than an antenna fed with 50 feet of coax at
35 feet, are you?

Thanks to all those that have offered advice, I should have mentioned that I
am UK based.

I plan to put the antenna up this weekend so I will let the group know how I
get it goes with the TVI.

Cheers,

Paul

"Paul" wrote in message
...
Hi,

I would like to reposition my 2M/70cm Vertical (Diamond X50) to a higher
position.

One option is to mount it above the TV aerial, I understand that the
signal
radiation below the antenna is very small, does anyone have any experience
of a similar setup?

If so what kind of distances would you suggest between the antennae?

Obviously my main concern is TVI and poorer performance from the Diamond
due
to its close proximity to the TV aerial.

I'm using RG-213 for the Diamond and normal coax for the TV.

Any help or suggestions would be appreciated.

Cheers,

Paul

"Andy Cogswell" SHORECOGS at COMCAST DOT NET wrote in message
news
In other words, you're not saying that an antenna fed with 50 feet of
coax
mounted at 10 feet has less loss than an antenna fed with 50 feet of coax
at
35 feet, are you?


Lets me see now, if you put the aerial (antenna is for ants and yanks) 25
feet higher, you'll get total loss because the end of the co-ax will be 25
feet short of the rig!

:-))
Dave

"Paul" wrote in message ...
I plan to put the antenna up this weekend so I will let the group know how I
get it goes with the TVI.
Please do let us know how it goes. I'm looking to do the same with a
colinear. At the moment it's in the loft so below the TV aerial, but
in direct line of a bank of water tanks:-( which appear to be
"damping" (excuse the pun) some of the signal going out in that
direction, so I can't access one of the nearby repeaters.

Robert
M3NZU