Make Folded Dipoles and use a CATV balun backwards at the feedpoint.
Then you can use plain old RG-6 and F-Splitters. Not only is this
incredibly cheap, the entire antenna system is at DC ground*.
Caution, do not use Baluns with little capacitor inside.

*Use an F Grounding Block where the coax enters the house. And a
drip loop.

http://members.shaw.ca/weskyscan/ima...ldedDipole.gif

"David" wrote in message
...
Make Folded Dipoles and use a CATV balun backwards at the feedpoint.
Then you can use plain old RG-6 and F-Splitters. Not only is this
incredibly cheap, the entire antenna system is at DC ground*.
Caution, do not use Baluns with little capacitor inside.

*Use an F Grounding Block where the coax enters the house. And a
drip loop.

http://members.shaw.ca/weskyscan/ima...ldedDipole.gif

There is a potential problem here in that many, many baluns and splitters
intended for CATV have very poor performance at HF- i.e. balance is poor,
insertion loss can be well above theV/U values. For the splitters, port to
port isolation can be very poor, loss higher than may be acceptable.
Finally, I have yet to see a CATV Balun that is acceptable for out door use.
I wouldn't count on the system being at DC potential either- there are
several methods for creating a 4:1 balun- and seeing as how the wire used in
these baluns is smaller than #36 gauge- it wouldn't take much to fry it
anyway.
Wouldn't it be much simpler to build a classic dipole from single conductor
wire, place several clamp on #43 cores at the dipole to feedline transition
and forget about the CATV stuff and fragile twinlead??

Dale W4OP

On Mon, 18 Apr 2005 12:53:26 GMT, "Dale Parfitt"
wrote:


"David" wrote in message
.. .
Make Folded Dipoles and use a CATV balun backwards at the feedpoint.
Then you can use plain old RG-6 and F-Splitters. Not only is this
incredibly cheap, the entire antenna system is at DC ground*.
Caution, do not use Baluns with little capacitor inside.

*Use an F Grounding Block where the coax enters the house. And a
drip loop.

http://members.shaw.ca/weskyscan/ima...ldedDipole.gif

There is a potential problem here in that many, many baluns and splitters
intended for CATV have very poor performance at HF- i.e. balance is poor,
insertion loss can be well above theV/U values. For the splitters, port to
port isolation can be very poor, loss higher than may be acceptable.
Finally, I have yet to see a CATV Balun that is acceptable for out door use.
I wouldn't count on the system being at DC potential either- there are
several methods for creating a 4:1 balun- and seeing as how the wire used in
these baluns is smaller than #36 gauge- it wouldn't take much to fry it
anyway.
Wouldn't it be much simpler to build a classic dipole from single conductor
wire, place several clamp on #43 cores at the dipole to feedline transition
and forget about the CATV stuff and fragile twinlead??

Dale W4OP


I have built these suckers resonant at 6 mHz and survived tropical
storms. The purpose of DC ground (easily verified with a DVM with a
buzzer) is to bleed static charges, not substitute for accepted
lightning amelioration SOP.

As far as the perfomance at lower frequencies, the little suckers work
just fine. Don't let the 5-900 mHz specs fool you. As long as there
are no serices caps inside, they work way lower than 5 mHz.

Co-ax Seal under Scotch 33+ makes anything weatherproof.

These are definitely workingman's antennas, quite modest but also very
capable. They are more wideband than their single wire equivalents
(though theoretically not usable on even harmonics.) Make 3, one for
6, one for 10, one for 15. use an A/B/C switch and you'll have a lot
of fun.

David wrote:

I have built these suckers resonant at 6 mHz and survived tropical
storms. The purpose of DC ground (easily verified with a DVM with a
buzzer) is to bleed static charges, not substitute for accepted
lightning amelioration SOP.

As far as the perfomance at lower frequencies, the little suckers work
just fine. Don't let the 5-900 mHz specs fool you. As long as there
are no serices caps inside, they work way lower than 5 mHz.

Co-ax Seal under Scotch 33+ makes anything weatherproof.

These are definitely workingman's antennas, quite modest but also very
capable. They are more wideband than their single wire equivalents
(though theoretically not usable on even harmonics.) Make 3, one for
6, one for 10, one for 15. use an A/B/C switch and you'll have a lot
of fun.

The losses are already bad at 5 MHz and get worse as you go lower.
You may get away with them, but you might not hear a really weak signal
you're looking for because of the added losses. Have you measured the
insertion losses for properly terminated two way splitters? I would
open the case, remove the directional coupler and install a couple
hybrid amps and protection circuits to help match the 50 Ohm impedance
and maybe give a dB or two of gain. Have you measured the return loss
of any of the splitters?

I built a 1 in, 32 out distribution amplifier for Microdyne to
distribute their 10 Mhz in house frequency standard. I used the LH0002
buffer amps, but there are newer parts with even better performance.
The advantage of individually buffered outputs is that any noise
generated by one load isn't reflected back into another load and you can
connect or disconnect equipment without affecting other loads.
--
Former professional electron wrangler.

Michael A. Terrell
Central Florida

David wrote:

Make Folded Dipoles and use a CATV balun backwards at the feedpoint.
Then you can use plain old RG-6 and F-Splitters. Not only is this
incredibly cheap, the entire antenna system is at DC ground*.
Caution, do not use Baluns with little capacitor inside.

*Use an F Grounding Block where the coax enters the house. And a
drip loop.

http://members.shaw.ca/weskyscan/ima...ldedDipole.gif

I'd be a bit sceptical of that 300-75 ohm TV type balun. But then again I'm
sceptical of anything that's 75 ohms.

dxAce
Michigan
USA

On Mon, 18 Apr 2005 10:18:31 -0400, dxAce
wrote:



David wrote:

Make Folded Dipoles and use a CATV balun backwards at the feedpoint.
Then you can use plain old RG-6 and F-Splitters. Not only is this
incredibly cheap, the entire antenna system is at DC ground*.
Caution, do not use Baluns with little capacitor inside.

*Use an F Grounding Block where the coax enters the house. And a
drip loop.

http://members.shaw.ca/weskyscan/ima...ldedDipole.gif

I'd be a bit sceptical of that 300-75 ohm TV type balun. But then again I'm
sceptical of anything that's 75 ohms.

dxAce
Michigan
USA


It's a hobby experiment thing. Springtime. I tried it just for fun
and got surprisingly good results.

"dxAce" wrote in message
...


David wrote:

Make Folded Dipoles and use a CATV balun backwards at the feedpoint.
Then you can use plain old RG-6 and F-Splitters. Not only is this
incredibly cheap, the entire antenna system is at DC ground*.
Caution, do not use Baluns with little capacitor inside.

*Use an F Grounding Block where the coax enters the house. And a
drip loop.

http://members.shaw.ca/weskyscan/ima...ldedDipole.gif

I'd be a bit sceptical of that 300-75 ohm TV type balun. But then again
I'm
sceptical of anything that's 75 ohms.

dxAce
Michigan
USA

Several years back I had a contract to characterize a variety of CATV
splitters for marine use. Port to port isolation was abysmal below 5MHz,
insertion loss and return loss well below rated spec - Their need extended
down to MW, so I could not recommend any of the ones we tested.
If you have a field strength meter, here's a simple test to evaluate a
baluns actual balance.
Connect the 75 Ohm end the the FSM input. Connect a short wire to one lead
of the 300 Ohm end; tune in a loud SW station near the freq of interest and
note its level in dB. Being careful not to move the wire, short both sides
of the 300 Ohm and note the new level. At V/U the change is typically 30dB
indicating acceptable balance and pretty much guaranteeing the outer shield
of the coax will not be a significant part of your antenna. At HF, its
anybody's guess.

I seem to recall that the wider bandwidth of the folded dipole configuration
is attributable to the effective larger diameter conductor- probably easily
offset by using a larger wire diameter in a classic wire dipole.

Dale W4OP

On Mon, 18 Apr 2005 16:36:24 GMT, "Dale Parfitt"
I seem to recall that the wider bandwidth of the folded dipole configuration
is attributable to the effective larger diameter conductor- probably easily
offset by using a larger wire diameter in a classic wire dipole.

Dale W4OP
The dipole wire would have to be a half-inch in diameter for plain old
TV Twinlead. A T2FD is an example of a widebanded folded dipole.

http://www.bwantennas.com/pro/fdipole.pro.htm

David,

In article ,
"Michael A. Terrell" wrote:

David wrote:

I have built these suckers resonant at 6 mHz and survived tropical
storms. The purpose of DC ground (easily verified with a DVM with a
buzzer) is to bleed static charges, not substitute for accepted
lightning amelioration SOP.

As far as the perfomance at lower frequencies, the little suckers work
just fine. Don't let the 5-900 mHz specs fool you. As long as there
are no serices caps inside, they work way lower than 5 mHz.

Co-ax Seal under Scotch 33+ makes anything weatherproof.

These are definitely workingman's antennas, quite modest but also very
capable. They are more wideband than their single wire equivalents
(though theoretically not usable on even harmonics.) Make 3, one for
6, one for 10, one for 15. use an A/B/C switch and you'll have a lot
of fun.

The losses are already bad at 5 MHz and get worse as you go lower.
You may get away with them, but you might not hear a really weak signal
you're looking for because of the added losses. Have you measured the
insertion losses for properly terminated two way splitters? I would
open the case, remove the directional coupler and install a couple
hybrid amps and protection circuits to help match the 50 Ohm impedance
and maybe give a dB or two of gain. Have you measured the return loss
of any of the splitters?

I built a 1 in, 32 out distribution amplifier for Microdyne to
distribute their 10 Mhz in house frequency standard. I used the LH0002
buffer amps, but there are newer parts with even better performance.
The advantage of individually buffered outputs is that any noise
generated by one load isn't reflected back into another load and you can
connect or disconnect equipment without affecting other loads.

Yes, the active devices will provide good output to output isolation.

One drawback of any passive splitter is poor isolation.

--
Telamon
Ventura, California