"WB3FUP (Mike Hall)" wrote in message
...
You will be a much happier camper if you feed it with 450 ohm ladder line.
You will have no trouble using the antenna anywhere from 80 to 10, and if
snipped

I need to run the feeder from my dipole (80m) up thro the eaves, thro' the
loft-space to the shack at the other side (1st floor) of the house, approx
50'. No other routes feasible. Because of the route, I thought I'd have
less problems using coax, BUT from the remarks in the above recent post,
will someone kindly comment on viability of 450 ohm twin feeder over such a
route?

Many thanks
Jim M0Jim

Replies to NG pse!!

I need to run the feeder from my dipole (80m) up thro the eaves, thro'
the
loft-space to the shack at the other side (1st floor) of the house, approx
50'. No other routes feasible. Because of the route, I thought I'd have
less problems using coax, BUT from the remarks in the above recent post,
will someone kindly comment on viability of 450 ohm twin feeder over such
a
route?

=====================================

If necessary just squeeze heavy-duty 450-ohm ladder line wires close
together wherever they pass through a small hole. Line holes with a thick
plastic film or a pipe to obtain a higher breakdown voltage. Slowly twist
the cable every 2 feet between holes and keep it at least 1 or 2 inches away
from foreign materials, long metal conductors or otherwise.

If it was possible to do A-B comparisons at HF you would find little
difference - equivalent to a few pF change in a tuner capacitor setting and
1/2-turn change in the roller inductor. To be safe stick to 100 or 200 watts
unless you wish to test to destruction under worst case, but controlled
conditions (eg., very high SWR) just to see what happens. Probably nothing!

At HF a change in impedance Zo over a length of a few inches when passing
through one or two holes in timber or brickwork will have a negligible
effect on performance. The advantage of a balanced line all the way to the
transmitter may be that a tuner can be located in the shack. If an automatic
tuner is used then use easier-to-install coax and locate the tuner at the
antenna end.

Over a length of 50 or more feet, at 28 MHz, the lower loss in 450-ohm line
relative to 50-ohm RG-58 is worth thinking about. At 1.9 MHz forget it.

But it's only a matter of economics, time and labour, and the well-earned
satisfaction of having done a good job which works according to plan.
---
Reg, G4FGQ

Jim,
If you follow the 'normal' rules for using twin-
lead feed line you shouldn't have any more (or any
less) problems than if you used coax. There is always
the possibility that RF will 'eat up' all the electrical
appliances in your house, but maybe not.
Nothing except your pocket says you can't change feed
lines or antenna if you want. So, try it and see what
happens...
'Doc

I use such an antenna but feed it differently. Mine is 130 ft long and fed
with 300-Ohm xmitting twin lead.

The transmission line connects to the balanced output of a MFJ tuner.

Used it on all bands 80 through 6 till I got a 6-m Yagi and a tribander.

It is still a much used antenna, especially on 80, 40, 18, and 24.

On 40 it is a fullwave doublet and has about 1.5 dB gain over a dipole.

I have used it in 160 by shorting the two wires of the twinlead together and
feeding it as a Marconi antenna.

I agree with other posters who wud like to see the center a little higher, but
a man's gotta do what a man's gotta do!

Have fun, Jack K9CUN