[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

RE: Antenna suggestions

> My apologies to Richard; it wasn't my intention to take over 
> his thread.
> I've tried the K5OE eggbeater on 70cm. I originally built it with LHCP
> accidentally. When I switched it to RHCP The SWR went wild 
> and I never got
> to the bottom of the problem. My personal experience of 
> building my own
> antennas is a long and unsuccessful one. Somehow I just don't have the
> knack.

Well, keep at it.  A lot of my early antenna projects were failures too.
Fortunately these days, the success rate is a lot higher (though I haven't
cracked a good 23cm antenna yet though, lots of failures there - that's my
next antenna project!).

> I ordered the M2 2m and 70cm eggbeaters with radial kits and 
> they arrived
> about two weeks ago. Any comments about using or not using 
> the radial kits
> on either band? I'm thinking about the performance at the 
> horizon as well as
> overhead.

Without seeing the design, I can't comment. :-(

> Now here's the rap... There's about 160' of RG213 (and 'RG213 
> Type' at that)
> going up to the roof. I think that at 70cm I get about 10dB 
> attenuation. But
> I can certainly still hear the birds as they go over, just 
> loads of noise
> and QSB. I certainly have no problem getting a signal into 
> RS13 on 2m down
> the same coax to a vertical.

10 dB, yuk!  I find even a few dB of coax loss can make things considerably
more difficult, to the point that I find a 1/2 wave whip on a HT much better
than the shack vertical.  If I could, in this situation, I'd be running a
decent preamp to minimise the effect of coax loss.

I haven't tried any specialised omnidirectional antennas yet (turnstile,
eggbeater, etc).  I find the beam gives me a much more stable signal than
any of the previous verticals and handheld whips) did.

> So last weekend I built a 160' harness of two Westflex 103 
> (like 9913) coax
> lengths, two rotator cables and a multi core control cable 
> for the preamps
> and future remote antenna and polarization switching. attenuation is
> measured at 5dB on 70cm and 3dB on 2m. I haven't had the 
> nerve to put it

Better, but that's about my loss on 70 and I'm not satisfied with system
performance.  I'll look into better coax (using about 60' of 213) next time
I do maintainance.  Last time round, I eliminated about 20' of cable and a
few PL-259 connectors (replaced those with a single N connector join) and
gained 10dB, making 70cm useful for terrestrial work. 

> My QTH problem is a strange one. The visibility aspect is not 
> directly a
> problem, as unless I put the antennas on top of a 30' tower 
> on the roof
> you're never going to be able to see them from the street. 
> I'm in an urban
> area surrounded by other buildings of similar heights. My 
> tenancy is a long
> lease (999 years) which is an English legal device. This 
> means you have a
> freeholder, who I technically should get permission from to 
> do anything in
> the communal parts of the apartment block, like the roof. And 
> we all know
> what the easiest answer's going to be if I actually ask. 
> There's about a
> dozen 2'-7' sat TV dishes already up there, so with a bit of gradual
> incursion I should be able to get something a bit more 
> serious up over time.

Mu QTH problem is different again.  The landlady is quite co-operative and
I've had one antenna up for 5-6 years.  Originally, it was a vertical for
the UHF CB band, but as ham activity takes precedence these days, it was
replaced by a Diamond tri bander (6/2/70).

My problem is literally a lack of places to hang antennas from, without
making the house look like a feral porcupine.  Don't want to upset the
landlady too much.  My solution is to simply go portable (even if only out
the front), which has been working well on the FM birds.  Have to build a
transverter before I can try the Fujis or AO-10 though, the SSB gear I have
so far is all portable, so there won't be any major dramas in that area.
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org