[amsat-bb] Making progress
s.wilson at yahoo.com
Tue Aug 7 19:57:05 PDT 2007
Bill Ress wrote:
> While Tony is modest, you can get his design and construction details
> for both his 146 and 435 MHz antenna's in the 2006 AMSAT Symposium
> Proceedings (available on the AMSAT website - I know a callous plug!!).
The lindenblads are not only the most approachable DIY solutions that
I've seen, they are also the only ones that seem like they'll work when
you're done with them. I can't comment on them directly, but when it's
time to try out an omni, those will be the ones I build. I appreciated
the very detailed diagrams about how the matching coax should be cut. I
felt that the other omni plans left out that very important detail -
especially considering the importance the phasing and matching section
play in their designs.
I would like to report some additional progress! During tonight's AO-51
pass over the central US, I managed to clearly copy a few call signs and
portions of a few QSOs. It is a small step from last week's work, but it
proves to me that the fixed elevation yagi is serviceable and that I am
getting a return on investment. Yesterday I replaced the questionable
RG-58 with RG-213.
I have planned a few changes to the existing feed line configuration
which will allow me to work 2m and 440 with seperate transceivers. I've
also ordered an SSB preamp for the 70cm band. I am considering LMR-400
flex for the 70cm feed and keeping the RG-213 for the 2m feed.
The preamp was a concern for me in that since I've been working HF, I've
found that I receive much clearer with the preamp disabled and the
attenuator enabled and just pushing up the AF gain. I realize this is
due to noise in the area and the fact that the IC-7000 preamp is a
broadband preamp, and generally will just increase the noise floor and
lower the sensitivity of the frequencies I'm actually interested in.
Tonight I confirmed that I cannot copy any AO-51 signal without the
IC7000 preamp engaged. Hopefully this means that with a quality
narrowband mast mount preamp from SSB, I'll be able to bypass the
broadband preamp and increase overall sensitivity of the UHF receive
band. I know that everyone's saying that a preamp is an absolute must,
but I needed to clear that up before I could justify buying a preamp
when in other situations, it only makes things worse.
Again, thanks for your help. I'll let you all know as soon as I get
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