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VHF Antennas, as per PBR

Old 01-25-2007, 02:07 AM
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Default VHF Antennas, as per PBR

Here’s something the Digi-heads can argue over. In the Feb 2007 issue of Powerboat Reports they publish their comparison of 8-ft and 16-ft VHF antennas from 3 manufacturers. Here’s the ‘Bottom Line’ for each:

Comrad: Although the Comrod antennas came up a little short in the range test, and they are expensive, the tubes on these antennas are definitely overbuilt and would last a long time.

Digital: Even though they are expensive and their range fell short of the Shakespeare models in our tests, we feel that the Digital antennas offer great value because they are built with high-grade materials. If you want an antenna that will last over the long haul, the Digital antennas are excellent choices.

Shakespear: Shakespeare’s Galaxy antennas performed the best in our test. They are priced right, and readily available at most retail locations. Based on our internal inspections, however, we feel the Comrod and the Digital hold the edge in the durability department.

Ironically, Shakespeare’s 16-ft antenna bested the lot of long stick antennas for performance, and not by a little bit. But its construction can’t hold a candle to either a Comrod or a Digital.

Old 01-25-2007, 02:24 AM
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Default RE: VHF Antennas, as per PBR

I thought I posted this last night but can't find it. ;? Did I violate a copyright or something?
Old 01-25-2007, 06:02 AM
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Default Re: VHF Antennas, as per PBR

That’s weird. I can see where you posted a thread about it but I can’t access it. If you posted the whole article maybe that is the problem. I never post the whole article of a copyrighted piece, only highlights, like above.

Old 01-25-2007, 10:40 AM
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Default Re: VHF Antennas, as per PBR

Hmm, I just read the article. I am surprised Digital did so poorly in range given the construction. The article never made it clear whether the Comrod was hooked up with RG59 or 8X. I am in the process of getting my jumper made for mine with RG 8X low loss for the same reason specified in the article.

Makes me wonder what a dual VHF antenna setup would perform like. I wonder if it would increase range any.
Old 01-25-2007, 11:04 AM
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Default RE: VHF Antennas, as per PBR

Most folks that own Shakspeare Antennas don't own the high end Galaxy model which competes with Dig Ant. for nearly the same price.

The lower end Shakspeare antennas have marginal performance.



Old 01-25-2007, 11:14 AM
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Default Re: VHF Antennas, as per PBR

sigfla - 1/25/2007 10:40 AM

...The article never made it clear whether the Comrod was hooked up with RG59 or 8X....
Not RG 59 -- that's 75 ohm cable like is used on TV cable hookups. You must mean RG 58, which is really cheap 50 ohm cable (also, like RG 59) and has a solid center conductor). 8X has a stranded center conductor which is flexible and won't break from vibration.
Old 01-25-2007, 11:17 AM
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Default RE: VHF Antennas, as per PBR

I can say my experience with Shakespeare has always been that the lower end models break easily. On my friends boat which I fished on exclusively for many years before I bought my own he would buy a new cheap Shakespeare every year to replace broken ones. Eventually he bought a higher end Galaxy and I don't rememember him breaking it for quite a while before he sold the boat.

Antenna's which rattle around just don't inspire confidence. I assume the test used each manufacturers standard length cables? Again, they don't specify. With COMROD it could have been any number of lengths. I would like to see a real word test with the same RG8X low loss cable for all antenna's in varying lengths (short run v.s. long and affect on performance). I would also like to see a test between RG213 v.s RG8X.

Anyone ever test long v.s. short cable leads?
Old 01-25-2007, 11:19 AM
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Default Re: VHF Antennas, as per PBR

Thnks T3 I stand corrected you are right, RG 58.
Old 01-25-2007, 11:50 AM
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Default Re: VHF Antennas, as per PBR

...I would also like to see a test between RG213 v.s RG8X...
For the short runs on a boat and the limited power (25W), there will be no difference in performance. RG213, being about 1/2" in diameter, will be significantly more difficult to install and will require much bigger radius for the bends. In fact, if you bend 213 too sharply, the center conductor can lose its dead center position (cut through the dielectric) and change the characteristic impedance of the cable (to its detriment). Stick with RG8x.

AVOID RG58/U LIKE THE PLAGUE. It has no place on a boat because of the crappy shielding and solid center conductor. One of the significant things to look for in cable quality is the % coverage of the shielding -- the higher, the better.

I use 213 (similar) on the run from my ham station to the antennas on my tower, but the run is 100' and the power is 1500 Watts.
Old 01-25-2007, 12:10 PM
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Default Re: VHF Antennas, as per PBR

I think that everyone can calculate their own loss and power output from the chart below. Just interpolate to your cable length. The columns don't line up due the cut and paste. The last column is power out (pout). For easier reading to this site:

http://hamradio.arc.nasa.gov/coaxcableloss.html

Coax Cable Loss
These calculations for Pout (Power out in watts) are for an input of 50 watts.
Cables listed are typical coax cables by Belden.

For 100 ft cables: RG-8/U, Belden 8214 RG-8X, Belden 9258
MHz dB/100 ft Pout MHz dB/100 ft Pout
50 1.2 38 50 2.1 31
100 1.7 34 100 3.1 24
200 2.6 27 200 4.5 18
400 3.9 20 400 6.6 11
700 5.6 14 700 9.1 6

RG-8/U, Belden 9913 RG-8/U, Belden 9913F
MHz dB/100 ft Pout MHz dB/100 ft Pout
50 0.9 41 50 1.1 39
100 1.3 37 100 1.5 35
200 1.8 33 200 2.0 32
400 2.7 27 400 2.9 26
700 3.6 22 700 3.9 20

RG-58/U, Belden 8240 RG-58C/U, Belden 8259
MHz dB/100 ft Pout MHz dB/100 ft Pout
50 2.5 28 50 3.7 21
100 3.8 21 100 5.4 14
200 5.6 14 200 8.1 8
400 8.4 7 400 12.4 3
700 11.7 3 700 17.7 1

RG-174/U, Belden 8216 RG-59/U, Belden 8241
MHz dB/100 ft Pout MHz dB/100 ft Pout
50 5.8 13 50 2.4 29
100 8.4 7 100 3.4 23
200 12.5 3 200 4.9 16
400 19 1 400 7.0 10
700 27 0.1 700 9.7 5
Note: RG-59 is 75-ohm cable TV coax.

For 50 ft cables: RG-8/U, Belden 8214 RG-8X, Belden 9258
MHz dB/50 ft Pout MHz dB/50 ft Pout
50 0.6 44 50 1.1 39
100 0.9 41 100 1.6 35
200 1.3 37 200 2.3 29
400 2.0 32 400 3.3 23
700 2.8 26 700 4.6 17

RG-8/U, Belden 9913 RG-8/U, Belden 9913F
MHz dB/50 ft Pout MHz dB/50 ft Pout
50 0.5 45 50 0.6 44
100 0.7 43 100 0.8 42
200 0.9 41 200 1.0 40
400 1.4 37 400 1.5 36
700 1.8 33 700 2.0 32

RG-58/U, Belden 8240 RG-58C/U, Belden 8259
MHz dB/50 ft Pout MHz dB/50 ft Pout
50 1.3 37 50 1.9 33
100 1.9 32 100 2.7 27
200 2.8 26 200 4.1 20
400 4.2 19 400 6.2 12
700 5.9 13 700 8.9 7

RG-174/U, Belden 8216 RG-59/U, Belden 8241
MHz dB/50 ft Pout MHz dB/50 ft Pout
50 2.9 26 50 1.2 38
100 4.2 19 100 1.7 34
200 6.3 12 200 2.5 28
400 9.5 6 400 3.5 22
700 13.5 2 700 4.9 16
Note: RG-59 is 75-ohm cable TV coax.

For 25 ft cables: RG-8/U, Belden 8214 RG-8X, Belden 9258
MHz dB/25 ft Pout MHz dB/25 ft Pout
50 0.3 47 50 0.6 44
100 0.5 45 100 0.8 42
200 0.7 43 200 1.1 38
400 1.0 40 400 1.7 34
700 1.4 36 700 2.3 29

RG-8/U, Belden 9913 RG-8/U, Belden 9913F
MHz dB/25 ft Pout MHz dB/25 ft Pout
50 0.2 47 50 0.3 47
100 0.3 46 100 0.4 46
200 0.5 45 200 0.5 45
400 0.7 43 400 0.7 42
700 0.9 41 700 1.0 40

RG-58/U, Belden 8240 RG-58C/U, Belden 8259
MHz dB/25 ft Pout MHz dB/25 ft Pout
50 0.6 43 50 0.9 40
100 1.0 40 100 1.4 37
200 1.4 36 200 2.0 31
400 2.1 31 400 3.1 24
700 2.9 25 700 4.4 18

RG-174/U, Belden 8216 RG-59/U, Belden 8241
MHz dB/25 ft Pout MHz dB/25 ft Pout
50 1.5 36 50 0.6 44
100 2.1 31 100 0.9 41
200 3.1 24 200 1.2 38
400 4.8 17 400 1.8 33
700 6.8 11 700 2.4 29
Note: RG-59 is 75-ohm cable TV coax.









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