AD5VJ Bob wrote:
> As I have been reading on the 80 meter dipole antennas I understand that you
> will not be able to cover the entire band due to the
> size of the band, so I will attempt to zero in on the DX portion of the band.
Like usual this is more than what was asked but I wasn't sure what was
I sent this note once and it apparently disappeared, ...or I hit the
At-any-rate, you can cover the entire band depending on what you are
using for equipment. The simple dipole doesn't care what the SWR is, nor
will it affect the efficiency. That antenna will radiate all the power
IIRC the additional power loss _in_the_coax_ from a 5:1 SWR on 3.5 MHz
is only about 0.26 db or around 14 watts PEP when running 200 watts output.
> My question is on the other portions where I will be less efficient than 1:1
> say around 2:1 and up - if I use a tuner and bring the
> swr to 1:1 will I still have the same 200W ERP at the antenna as I would
> using the 1:1 portion of the band or is the additional
> power lost in the tuner?
There is very little power lost in the tuner with most being lost in the
coax due to the SWR. However I'd avoid the tuner (if possible) as it
just adds complexity. IOW it's just one more thing to go wrong.
In my case I have a solid state KW (out in the shop)with all kinds of
protection built in and it needs a tuner. I say that as it starts
shutting down at roughly 1.3:1 and power falls off rapidly. My old Alpha
76A will go most any where on 75 with out the need of a tuner. 160 is a
> If so how do I figure the ERP at the antenna when using a tuner?
ERP on a dipole? I'm not sure why you are asking about erp, but... For
exposure purposes? ERP is based on a dipole reference so with the
dipole it is the radiated power not effective. You'd have to do a
search but "coax line loss calculator" entered into Google will get you
a "Plug in the numbers" type of calculator. You then take those numbers
to http://n5xu.ece.utexas.edu/rfsafety/ which will probably require
less than a half a foot clearance at 200 watts however the duty cycle
for SSB is 20%. Then you still figure your transmit time for the
controlled and uncontrolled areas
A ham can go to that site, plug in the max power they run on each band
with each antenna, print them off and have a record to make the FCC happy.
> Bob AD5VJ
>> -----Original Message-----
>> From: email@example.com
>> [mailto:firstname.lastname@example.org] On Behalf Of AD5VJ Bob
>> Sent: Sunday, November 16, 2008 7:34 AM
>> To: email@example.com
>> Subject: [TowerTalk] Dipole Center Connector
>> I am working on building a dipole for 80 meters.
>> I have the wire, poles and rope needed to string it, but dont
>> have the money right now to buy the Budwig PL-259 center
>> connector for it.
>> Any ideas what I can use that will actually keep the antenna
>> up there for a while, I have come up with some ideas, but
>> would like to work from good ol' reliable successful
>> experience instead of trying to reinvent the wheel.
>> 73 fer nw es gud DX,
>> QSL VIA: LotW, BUR, e-QSL
>> Bob AD5VJ
>> Old Calls WB5ZQU, WY5L/KH3, KE5CTY, N5IET
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