"Jason Dugas" wrote in message
...
Hello all,

I have a 6m transverter on the way this week to use just in time for the
CQWW contest this weekend... one problem NO ANTENNA!!

So I picked up a very old Yagi, built in 1969, but still in great
condition.
Its currently cut for the 40 MHz band, so I should be able to trim the
elements down and change the spacing for a 3-element 6m antenna, right?

Jason -

Do you know who made the original Yagi? Is it aluminum tuning or solid rod?

The fastest method is to shorten the reflector, director and driven
elements, BUT
maintain the element spacing. Later - you can look at changing the element
spacing - if desired.

w9gb
--
DO NOT use Reply.
Only reply through ARRL forwarding service to W9GB

The elements are "solid rod" I believe. What are the consequences of not
changing the spacing, while cutting the elements to the right lengths? Loss
of directivity would be my guess, but I'd still have a good radiator with
relatively low SWR?

Thanks,

Jason
"G.Beat" wrote in message
news:NF1Qa.44293$GL4.12054@rwcrnsc53...

"Jason Dugas" wrote in message
...
Hello all,

I have a 6m transverter on the way this week to use just in time for
the
CQWW contest this weekend... one problem NO ANTENNA!!

So I picked up a very old Yagi, built in 1969, but still in great
condition.
Its currently cut for the 40 MHz band, so I should be able to trim the
elements down and change the spacing for a 3-element 6m antenna, right?

Jason -

Do you know who made the original Yagi? Is it aluminum tuning or solid
rod?

The fastest method is to shorten the reflector, director and driven
elements, BUT
maintain the element spacing. Later - you can look at changing the
element
spacing - if desired.

w9gb
--
DO NOT use Reply.
Only reply through ARRL forwarding service to W9GB

"Jason Dugas" wrote in message
...
The elements are "solid rod" I believe. What are the consequences of not
changing the spacing, while cutting the elements to the right lengths?
Loss
of directivity would be my guess, but I'd still have a good radiator with
relatively low SWR?


Jason -

With solid rod elements - you are in a "measure at LEAST twice and cut once"
situation.

Most likely the directive lobe would not be optimized.
You can use antenna modeling software to see the specific results, BUT this
gets you on the air quickly.

w9gb
--
DO NOT use Reply.
Only reply through ARRL forwarding service to W9GB

"Jason Dugas" wrote in message ...
The elements are "solid rod" I believe. What are the consequences of not
changing the spacing, while cutting the elements to the right lengths? Loss
of directivity would be my guess, but I'd still have a good radiator with
relatively low SWR?

If it were for 40 mhz, the spacing at 50 mhz should be usable as is I
bet. What I'd do is model the antenna with the current spacing, but
with the new element lengths and see what the pattern looks like.
Being the boom is longer on a 40 mhz beam than the 50 mhz, you have
the potential to have a long boom antenna. If the 40 mhz beam was a
"short" maximum f/b ratio antenna, it might be about right on 6m as a
max gain antenna. My 6m beam is 3 elements and copied after the NBS
yagi. The boom is 8 ft long. It's set up for maximum gain and mediocre
f/b ratio. But many people use a 6 ft boom on a 3 el 6m yagi to have
a better f/b ratio with slightly less gain. The spacing is not overly
critical just to operate with decent gain. But you could respace if
you decide to optimise the antenna for your exact wants. My beam is
exactly copied from the one in the elnec or eznec demo. "NBS yagi"
It's 1/2 copper tubing same as the model. The real world results
closely matched what it modeled. MK