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

Re: Another interesting preamp story



At 01:23 PM 3/25/06 -0600, k0vty@juno.com wrote:
>Lets see:
>Going back a very long time when these troubles got me going .
>Things to think about from my memory:
>RF coupling though the air.
>Proper good grounding of all units
>Proper terminations
>Separate ground shielded coax for the DC to each unit
>The use of one signal coax , antennas to shack using duplexers
>at the two coax ends.
>Rotate antenna booms for minimum coupling through air.
>All wire to antennas are shielded.
>
>In my antenna mounting , there is an added boom perpendicular to the
>normal cross
>boom holding the antennas.
>This added boom mounts the preamps, power dividers I used to run pairs of
>KLM yagis ) etc, at a place equal to the distance that the rear dipoles
>on the KLM antennas are to the normal cross boom
>Balance on the cross very important.
>This allows coax with a length that has a minimum fixed number of half
>waves to connect the preamps
>to maintain 50 oHm impedance points .
>The output of the preamps has likewise equal lengths of coax to a
>duplxerer.
>Another duplexer can be used ahead of the 70 cm preamp if J desense if
>still troubling.
>This methodology works for me at 160 watts when needed.
>
>Keep everything ground and with equal impedance point connections.
>Coax can provide strange couplings sometimes
>
>I hope I have remembered some of the pints that might help
>
>Joe  K0VTY
>Amsat # 860
>========================


Thanks Joe.  Most of what you recommend I do already.  I think when the 
time comes for a 2M pre-amp, I buy a ssb electronic and try that, might 
have better filtering.  Doesn't hurt to own more than one.  I use the 2 
meter one now when I do satellite demonstrations at meetings, or when I go 
out and try a little aurora prop, so it's still useful.
----
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home