300 ohm ladder line on 11 meters ?

[Squints]

Back in the 1980,s i had a base antenna 40 feet up in a tree but was 1000 feet away from my house on top of a great big hill in the appalachian mountains.
I used twin lead ladder line the entire 1000 feet with 11.5 feet of rg 8 coax on each end made into open choke coils then about 6 feet or more that went from the coil to the antenna or transmitter.
The ladder line had always laid on the ground and never seemed to have any significant loss when compared to the 1000 feet of rg 8 coax feed line i switched over to after using the ladder line for 2 years.
I learned this the hard way after spending cash on all that coax that i thought would make a moneys worth of differance yet the final result was almost the same when just the feed line was changed.

 

[Captain Kilowatt]

Good quality RG-213 which is an RG-8 type of cable has a loss of 1.0 dB per hundred feet, so your best case was that you had 10 dB loss in your coax cable. You say the ladder line showed no difference, which proves that from it laying on the ground, losses were crazy high for what they could have been if the cable was strung up in the clear. Having around 10 dB loss with ladder line is unheard of in normal usage. You could have made more of a difference if you just installed the ladder line on posts up off the ground and kept it away from the ground.

 

[Uncle Ronnie 336]

digging up old bones here. 150' of 8x for me loses 20-25 watts between a 1 and 1.5 swr per 150'. im a working class guy so doing LMR for that run is not in the budget. so my plan is to make my own, around 450-500 ohm balanced feed, with a monoband feedline balun/1/4wave line transformation, which as i read presents way less loss than a multiband 43 torroid balun. i'm thinkin one of these bad boys on either end, but my monkey brain was also lookin at other balanced antenna designs like a rhombic that are optimal between 600-800 ohms that i can put up for the winter in the field. last cut of hay went out this weekend

 

[Tom Line]

In reading about dublett antennas using twinlead and antennas needing 4:1 matching due to twinlead/coax connections, I keep seeing claims that there's less noise and better SNR than some other antennas because of the symetrical nature of the matching system??? I don't know, was just wondering.

 

[Uncle Ronnie 336]

In reading about dublett antennas using twinlead and antennas needing 4:1 matching due to twinlead/coax connections, I keep seeing claims that there's less noise and better SNR than some other antennas because of the symetrical nature of the matching system??? I don't know, was just wondering.

a balun like this one I posted for monoband or a torroidal for multi-band will improve snr. kills common mode currents. im looking to get the best of both worlds here by using coax in the house but balanced outside

 

[wavrider]

Think out of the box.

I use RG6 quad coax, two pieces side by side as twin lead.
RG6 is cheap and available on line and at big box stores.
Twist the shields together use center conductor just like twinlead works great and can be run next to or through metal.
doesn't flap around in the wind like ladderline does and is a lot less expensive.
I picked up a 1000 foot roll at the local flea market for 7 bucks, still in the box

 

[AudioShockwav]

I have learned a lot over the years playing radio, if you grow in the hobby only knowing coax you get conditioned that it is the only way to feed antennas.
Old school guys used what ever they had that was cheap.

73
Jeff

 

[Uncle Ronnie 336]

Think out of the box.

I use RG6 quad coax, two pieces side by side as twin lead.
RG6 is cheap and available on line and at big box stores.
Twist the shields together use center conductor just like twinlead works great and can be run next to or through metal.
doesn't flap around in the wind like ladderline does and is a lot less expensive.
I picked up a 1000 foot roll at the local flea market for 7 bucks, still in the box

ah yea. 150 ohm. i'd be interested due to the coaxial nature of each lead how loss would stack up compared to 300, 450, or 600. I imagine it'd be good as a 1/4~ impedance line transformer in the very least.

 

[wavrider]

ah yea. 150 ohm. i'd be interested due to the coaxial nature of each lead how loss would stack up compared to 300, 450, or 600. I imagine it'd be good as a 1/4~ impedance line transformer in the very least.

I put two wires up, one N/S other E/W used LB Cebik recommendation's from his top 5 favorite back yard antennas.
40 thru 10 meter doublet laddrline fed,
so one antenna is fed with 450 ohm ladderline
other is fed with rg6 quad .
I do not think it is 150 ohm impedance as the tune settings only need a slight touch of capacitance from one antenna to the other.
Both feedlines are with in 5 feet in length of each other.
The antennas are identical lengths 44 feet per leg.
I could really care less if it is 150 or 600 ohm, it works and is cheap.
but I was surprised that the ATU settings were very close to the same as I thought the RG6 would definitely be different settings to achieve a good impedance.

 

[Uncle Ronnie 336]

what is the impedance of two 75 ohm as a coaxed balanced feed? i've read about ppl doing it before.

 

[Captain Kilowatt]

what is the impedance of two 75 ohm as a coaxed balanced feed? i've read about ppl doing it before.

That would make 150 ohm feedline. When you use two lengths of coax to make balanced feedline the impedance is twice that of a single run of cable. Something to think about however is that feedline losses are more inline with coaxial losses not true open wire line.

 

[AudioShockwav]

That would make 150 ohm feedline. When you use two lengths of coax to make balanced feedline the impedance is twice that of a single run of cable. Something to think about however is that feedline losses are more inline with coaxial losses not true open wire line.

Yep, you would be better off with open feedline on long runs.

73
Jeff

 

[wavrider]

An analysis of current flow at the end of shielded twin line at radio frequencies

Owen explains it pretty good

 

[Uncle Ronnie 336]

That would make 150 ohm feedline. When you use two lengths of coax to make balanced feedline the impedance is twice that of a single run of cable. Something to think about however is that feedline losses are more inline with coaxial losses not true open wire line.

yea thats what i figured. i ordered some 450 ohm and im about to make some coax baluns/line transformers for either end of the run. also got myself a dpdt knife switch so if theres a lot of lightning the whole system will be shunted to ground