Receive random longwire question

[W7TFO]

Length: 900'
Height AGL: 60'
Feed length +/-300'
Bands sought: 160m & 75m
Orientation/support: SW-NE wooden poles
12 ga. Copperweld

                ----Now----

Which works best in experience: Single length or center-tapped dipole?

If single length, is LDF-4 a good cable from the loss standpoint, or should I look to RG-62?

If center-tapped, does Twinax work OK for balanced feed into shack?

Not to be used for transmitting. Well, maybe on 600m

73DG

[KA0HCP]

Too many antenna terms, too many variables.

What do YOU want?

-A tuned resonant antenna or the convenience of just hanging something easily?

-Do you want local or Dx reception?

-End fed wire or Dipole?
-Are you willing to put a ground rod or counterpoise at the feed point for an end fed wire?

What feedline do you want to use?

There is no 'best' antenna.  You have to make decisions or provide more limiting factors. 

[KA0HCP]

p.s.
300ft can be a long distance to carry a signal depending on the line type and the frequency.  There may be greater losses in converting from an end fed wire that require Balun(s) for impedance matching.  OWL may be better alternative.

http://vk1od.net/calc/tl/tllc.php

Owen has a great line loss calculator than can help you choose a good line.

[W7TFO]

Not too many variables at all, I'm asking for advice from someone that has actually done this and knows how it performs.

If you have an operating 700' to 900' random RX antenna, please;

2 simple questions:

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Single end wire, or balanced dipole. (The term 'feed' doesn't apply to a RX only antenna, no?)

What type of coax would perform OK for the job. 
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Does not include the use of OWL for this job, too hard to run.

Results will be tabulated against one of those neat, $500 RX active loops.

Signals aplenty here, so is a bit of background noise but not from the usual suspects; plasma TV's, dimmers, switchers.  None within 1/2 mile.

73DG

[Steve - K4HX]

No experience with the sorts of antennas you asked about. However, in my experience with receive only antennas, cable loss on 160 or 80 meters is not much of a concern. Almost any cable is OK. I use RG-6. Some of the BC DX crowd like Twinax.

[KA2DZT]

D

I was out in the Sun all day.  So I'm a little confused.

Can you repeat the question??

F


BTW RG-6 should work fine for receive antennas.

[wa3dsp]

If its receive only you could use a FET or equivalent preamp at the antenna for a long coax run. That moves the noise figure out there and would not include the loss in the coax. Of course on low band HF that may not be a factor.

[KA2DZT]

I would think at the low end of the HF band, thermal noise is not a factor.  Low noise pre-amps can be very helpful in the VHF range, even on 10M-15M.

Fred

[Steve - K4HX]

It's easily checked. Tune to a clear freq in the middle of the day with the smallest IF BW you expect to use. Disconnect the antenna. If the noise level drops on your receiver, you don't need a preamp - with some possible exceptions if you are into very weak signal work.

[W7TFO]

I appreciate the data on the preamp, but it isn't in my question.

Does anyone have a friggin' LONG longwire RX antenna, and how does it stack up to the new hot-shot loops?

Do you run it single-ended or as a dipole?

Again, TIA.

73DG

[kb3ouk]

I use a 240 foot longwire occassionally, but it's only about 15 feet high. It's definitely weaker than dipole, maybe 1 or 2 S-units weaker.

[W0BTU]

Why don't you lower it from 60' to about 10', and make a Beverage receiving antenna out of it?
http://www.w0btu.com/Beverage_antennas.html

[W7TFO]

Why don't you lower it from 60' to about 10', and make a Beverage receiving antenna out of it? 

Can't for two reasons:

The property has a 50' granite pile in the middle of it.

The 10ac is 660' square, hence the hypotenuse of +/- 900', and lots of storage with access needed for it already on the property.

Up is the only way.

73DG

[KM1H]

I wouldnt use any long RG-6 feed using Copperweld on 600M and any serious SWR loss will be added to whatever the line loss is if its not matched.

All my long wires are Beverages but wire and SWR losses dont change due to height or at 600M. My 5 2 wire Beverages are fed with broadband matching transformers ( NOT baluns) and short runs of RG-6 to the relay box and then 750' of 1/2' CATV hardline back to the house. No preamps needed and works fine from around 100KHz to 30M.

Carl

[W3RSW]

A loop regardless of amplification is rotatable but usually very high Q, with all the attendent advantages and disadvantages thereof.  A static wire is not rotatable but can be varied in Q. That is a criteria you need in your comparison.

The wire will exhibit directionallity of varying vectors depending on frequency.  

Looks like you already know answers to some of your questions, and you know how we are on this board.  

We never answer questions in a cookbook fashion, because "it all depends."
Thats the fun of the avocation.

Why not model it?
http://hamsoft.ca/pages/mmana-gal.php

There are a couple of beverages on the MMANA site that correspond to what you may want. Keep in mind that 2.2 meters above ground level on 160 (on the one I'm looking at now) may correspond to many more meters AGL on higher frequencies. 

I suspect that few if any have built the exact two antennae that you want to compare to give you an "exact" answer. 

[KM1H]

I suspect that few if any have built the exact two antennae that you want to compare to give you an "exact" answer.  

 

I dont expect many people are loading antennas that are also crawling around and waving their antennae ...altho listening to some of the nutcases on 75 anything is possible.

[KL7OF]

I have a 900 ft long antenna that is 100 ft above ground...It is made from 1/8 inch 7 x 49 SS cable...I feed it at the shack end as a single wire thru a wall mounted tuner....I have had it up for several years now and have compared it to all the other antennas I have here....I don't use it for transmit at all (anymore) because it doesn't work as well as other tx antennas that I have...I don't use it for receive  because My other rx antennas work better...and are generally less noisy....I plan to shorten the 900 footer and put up another leg to turn it into a VEE antenna aimed at Europe....to Be used mostly on 40-75-160 Meters...  In Summary  I don't like the 900ft long wire because it doesn'r work very well and it is noisy on rx......

   I might suggest to you that you configure your antenna as a beverage and keep it 7 ft above ground and just follow the contour of the ground over hill and dale..(Or the 40ft pile in the center of your antenna run)  I have a beverage that goes down in the gully and comes back up again  I maintain its height at 7 ft above ground....(about 600ft long)  It works as a beverage should...Hope this helps...Your mileage may vary...Good Luck...Steve