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60m

Sonwatcher

Sonwatcher

Active Member
Apr 6, 2005
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Colorado
There is a restriction of 50 w PEP on 60m . What is the kicker is that the FCC bases this on an antenna with 0 db gain . I wonder how many factor in the forward gain of their antenna and actually reduce the wattage to compensate for the gain ? The FCC requires documentation of how you calculated the gain. Or you can go by the manufacturers posted gain . Or do you think most people ignore the gain issue and just adjust their output for 50 w PEP ?
 

I have to sort of agree with EDUK8TR, if any power adjustment is made at all. I honestly can't think of any commercially made antennas that have any gain on 60 meters, not sure there are any commercially made 60 meter antennas at all, are there? So far, all I've ever done is listen a little. Haven't found any good excuse to get on yet...
- 'Doc
 
I read somewhere its 50 watts into a dipole in free space.

But a dipole at the optimum height above ground will have about 2dB more gain than a dipole in free space.
 
dudmuck said:
I read somewhere its 50 watts into a dipole in free space.

But a dipole at the optimum height above ground will have about 2dB more gain than a dipole in free space.
Click to expand...
]
§97.303(s)--The New Rules for 5 MHz​

An amateur station having an operator holding a General, Advanced or Amateur Extra Class license may only transmit single sideband, suppressed-carrier (emission type 2K8J3E) upper sideband on the channels 5332 kHz, 5348 kHz, 5358 kHz, 5373 kHz and 5405 kHz. Amateur operators shall ensure that their transmission occupies only the 2.8 kHz centered around each of these frequencies. Transmissions shall not exceed an effective radiated power (ERP) of 50 W PEP. For the purpose of computing ERP, the transmitter PEP will be multiplied with the antenna gain relative to a dipole or the equivalent calculation in decibels. A half-wave dipole antenna will be presumed to have a gain of 0 dBd. Licensees using other antennas must maintain in their station records either manufacturer data on the antenna gain or calculations of the antenna gain. No amateur station shall cause harmful interference to stations authorized in the mobile and fixed services; nor is any amateur station protected from interference due to the operation of any such station.​

heres the way it's "supposed" to work: xmitter PEP X gain (in dB relative to a dipole) = 50

actually, "they" made a math error by assigning a dipole a value of 0 (zero). the formula works when you insert the numbers for a dipole:
xmitter pep X gain = 50
xmitter PEP X 0/0 = 50
xmitter PEP x 1 = 50
xmitter PEP = 50

but..... when you insert a value other than zero for gain, the formula becomes ( from a math viewpoint) incorrect. here is the formula for an antenna with 2 dB of gain:

xmitter pep X gain = 50
xmitter PEP X 2/0 = 50
xmitter PEP X ? =50
xmitter PEP = ?

the problem is (i'm a math major) is that there is no answer for division by or into ZERO. one is "undefined" and the other is "indeterminate" (by defination) Math Forum: Ask Dr. Math FAQ: Dividing by Zero

​
 
hmmm, I do not turn the power down at all!

The only commercial antennas I have found is a Hustler 60 meter resonator and a Lakeview 60 meter Hamstick.

I made a half wave dipole for 60 meter and made contacts to Australia and the Kingdom of Tonga.

Turn the power down? PLEASE!!!

I keep my FT-817ND at full power for 60 meter and I have no plans to turn it down! (y)
 
hookedon6 said:
]
heres the way it's "supposed" to work: xmitter PEP X gain (in dB relative to a dipole) = 50
Click to expand...

really? well 2dB of gain increases your power by 1.58 times.
because ratio = 10^(dB/10), like 1.58 = 10^(0.2)
So adding 2dB to 50 watts would give you 79 watts.

If you still dont believe, you could convert 50 watts to dBm using dBm = log10(mW)*10
47dBm = log10(50,000)*10
then you add 2dB of gain to 47dBm = 49dBm
And then back to watts: 79,432mW = 10^(49dBm/10)

You only use the dB value directly if your power levels are already in dB.
 
Calculate in transmission line losses by type of feed, and the mismatch that most people are running for 60m tuneup. Then calculate the ground losses in for the low dipoles that most people are running as well.

By the time you are done there, you could likely run 100W PEP at the transmitter and still be within the 50W PEP ERP limitation.

I would think it highly unlikely that anyone would look your way with a standard 100W rig on that band unless you had some monster arrays you were using.

It's a fun band though for sure. Laid back and generally more courteous ops than the 'normal' bands. I liked it quite a bit while I was running there with my FT-1000MP. I still have to do the conversion on my TS-2000 and haven't gotten around to it yet.

It tends to be a rag chewers band, people looking for an actual QSO.
 
That "zero dBd" just means that a dipole has no gain over a dipole, so the actual number to enter is not "zero", but "unity", or 1.

Remember that the decibel scale is logarithmic, and this calculation is not.
 
Beetle said:
That "zero dBd" just means that a dipole has no gain over a dipole, so the actual number to enter is not "zero", but "unity", or 1..
Click to expand...

err????, isn't that exactly what i said?:

(quote)
xmitter pep X gain = 50
xmitter PEP X 0/0 = 50
xmitter PEP x 1 = 50
xmitter PEP = 50



i do undersand what the intention of the regulation is, (and if it is computed as a log/log scale or not doesn't make any difference, the result will be the same).
but,.... the math error (and it is a math error) is in using a value of zero vs a value of (say) 1 for a di-pole.and then using the resultant value as a multiplication factor.

again... what is the value of 1/0 or 0/2 ???
 
Happy_Hamer said:
hmmm, I do not turn the power down at all!

The only commercial antennas I have found is a Hustler 60 meter resonator and a Lakeview 60 meter Hamstick.

I made a half wave dipole for 60 meter and made contacts to Australia and the Kingdom of Tonga.

Turn the power down? PLEASE!!!

I keep my FT-817ND at full power for 60 meter and I have no plans to turn it down! (y)
Click to expand...


Hammer my man !! Droppin' the hammer on those hapless hammies
smashfreak.gif
Hammer Time (y)
 
Oh yeah, 60 Meters. Well I can't get there at the moment on my HF aerial. I'm on a horizontal loop for the low end of 80 Meters. 60 M is too odd a harmonic spot for it and the on-board tuner on the Icom can't match it. The SWR there must be something over the 3:1 limit of my rig. Don't have a good outboard tuner at the moment but need to get one again. Last OB tuner I had matched the loop up on 60 easily.

So....long story even longer
290.gif
...when I have another tuner again, I'm sure I'll still have this loop and I figure the antenna should be db down on me, ....so I'm gonna pull a HAMER on 'em
smashfreak.gif
and keep the station at maximum output
49lpmxx.gif
Shucks, I'm gonna need that there 100 watts just to make up the difference that I know the loop is robbing me of.....damn robbers !!






Uh yeah, I'm in for 100 whiskeys

interview.gif
 
From what I was reading on this subject, this added db gain thing on 60m only comes into play when using a vertical, or beam, and reaaly didn't come into play on dipoles, zep's, random length wires, or G5RV's.....

But don't go by me, I'm still a total rookie when it comes to anything below 10 meters......
 
Well, I really like 60 meters. Nice people on that band in the south east.

BUT _ Shhhhh, from the looks of my s meter, some are running more than 50 watts no matter how you do the math.
 

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