[ADXA] bright ideas needed

Wed Mar 20 21:59:21 EDT 2024

Thanks, Stan - replacing the C3 with a Navassa-5 has always been a
consideration.   The C-3 has no traps and is a good design on 20, 15, and
10.  The elements are full size, with the 20M reflector almost 40 feet.  It
has 3 el on 10, and two on 20 and 15.    It’s usable on 17M and terrible on
12.   I could rebuild it into a Navassa.  I made an EZNEC file of the C-3
with all the tapers so I could play around with that too, but making it
work on 12 and 17 would really be a complete redesign.   I have plenty of
aluminum and hardware, so the conversion would be zero cost except for
energy!    Since I want to do whatever needs to be done to the tower and
replace the rotator before too long, I may put the C-3 back and start
leisurely building something else.  A Navassa clone with 6 meters would be
nice.

I have a spare Ham IV ready to go so that will probably be what I’ll do,
but I’ve heard good things about the Yaesu rotators.  This is my original
Ham 4 from 1986 and it has had the pot replaced once before.  That’s almost
20 years between repairs, so I’ve been lucky.

Thanks for the good advice, Stan.    Lots to think about.
73,
Dennis

On Wed, Mar 20, 2024 at 8:21 PM Stan Stockton <wa5rtg at gmail.com> wrote:

> 
> Dennis,
>
> If I were you I would take the time to do two things:
>
> I would duplicate the JK Navassa antenna which has full sized elements - 2
> for each of the five bands.  The antenna will be much better than the C3
> and will not have traps that will cause problems if they are not already
> causing problems.
>
> Multi-band Yagi Antenna <https://jkantennas.com/jk-navassa-5.html>
> jkantennas.com <https://jkantennas.com/jk-navassa-5.html>
> <https://jkantennas.com/jk-navassa-5.html>
> <https://jkantennas.com/jk-navassa-5.html>
> <https://jkantennas.com/jk-navassa-5.html>
> <https://jkantennas.com/jk-navassa-5.html>
>
> And for the manual -
> https://jkantennas.com/assets/jk-navassa-5-manual-summer-2019---w-6m-kit.pdf
>
> Of course you can buy one but I figure there is a thousand dollars to be
> saved if you want to make it yourself.
>
> I assume the rotator is a Hygain/CDE/MFJ model.  I had never used a Yaesu
> rotator until a few years ago.  The T2-X I installed at ZF9CW lasted about
> a year.  It was a rotator that had been completely refurbished by a W2
> recommended by KM5G if I remember correctly.  When it failed and I took it
> down it looked like it had been submerged in the Carribean sea for a month
> or so.  I replaced it with a Yaesu 2800 and it’s still working perfectly
> and visually still looks good.
>
> Stan, K5GO
>
>
>
> On Mar 20, 2024, at 7:39 PM, Dennis Schaefer <dennisw5rz at gmail.com> wrote:
>
> 
>
> I’ll look at the schematic again - I measured 500 ohms across the whole
> pot but the center wiper contact is open.  I tried a second control box -
> same result.   However, I need to see where that fuse is in the circuit -
> would be nice if that was it!   Thanks.
>
> On Wed, Mar 20, 2024 at 7:27 PM J. Setcer <j.setcer at gmail.com> wrote:
>
>> I have had that exact problem at least twice. Both times for me it was a
>> 1/8 amp, yea one-eighth of an amp, fuse in the control box. Not the pot up
>> in the rotor.
>>  I could NOT find a 1/8 amp fuse, so I used a 1/4 amp fuse both times.
>> (shame on me).
>>  Anyway, it's something you can try right from your chair.
>> -QJ
>>
>>
>> On Wed, Mar 20, 2024 at 6:59 PM Dennis Schaefer <dennisw5rz at gmail.com>
>> wrote:
>>
>>> My rotator quit indicating.  It rotates, but the pot in the motor unit
>>> has opened up.  I can run outside and see which way it is pointing, but
>>> that isn't very elegant, especially since my back and neck are still a
>>> little messed up.  I need a way to temporarily tell the direction until I
>>> get it fixed.
>>>
>>> I thought about a camera, but the way our house is arranged, the only
>>> window I can put one in faces West and gets direct sun into the lens
>>> several hours a day.  Its a cheap camera, and it might not hurt anything,
>>> but it would make the camera unusable for that time.  I could probably get
>>> an outdoor-rated camera and point it somewhere out of direct sun.  That's
>>> the only real solution I can think of.
>>>
>>> The antenna and rotator are on a Hazer that only comes down to the
>>> garage roof.  I can't climb on the roof anymore, so I think the Hazer is
>>> going to go away in favor of a more standard configuration.  Someone who
>>> knows way more than I do is coming by later in the week and will advise
>>> me.
>>>
>>> I will probably put the Force-12 C3 back up but I sure wish there was
>>> something I could do to make it work better, or at least have a better SWR,
>>> on 12 meters.  I guess a QRO antenna tuner would be the best option.  The
>>> 4.5 SWR on 12M doesn't make the amp very happy.  I have a Dentron tuner
>>> that is stout enough, but it does not have a bypass switch.  It would
>>> probably be easy to rig something with two switches, but that would have
>>> the possibility for accidentally running power into an open feed would
>>> always be there.  The C-3 has two direct coupled elements for 10 meters,
>>> and one is for operating FM above 28.9 Mhz.  I wish I knew what would
>>> happen if I extended that element to make it resonate on 12 meters.  I plan
>>> to get help to get this all done in one shot, so I don't have the luxury of
>>> time for antenna experimentation.
>>>
>>> Ideas or comments are welcome!
>>>
>>> 73,
>>> Dennis
>>>
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