hi and thank you for your answers. if i put a capacitor 180pf, i will have
180pf before the variable capacitor and 180pf after the variable capacitor. it
is ok?
Look a schematic about my connection before (with low swr) and after (with high
swr).
i would like to have the variable capacitor before the coax 2m (between
transmitter and the start of 2m coax) because i have put the capacitor inside a
box with motor oil and i would like to protect it from the rain. If i put the
variable capacitor between coax feeder and antenna's feedpoint then i must put
it out of the transmitter's metal house and i will have problems with the rain.
the schematic
http://tzitzikas.site90.net/files/swr_antenna.JPG
--- On Thu, 10/21/10, Drago <s59a@siol.net> wrote:
From: Drago <s59a@siol.net>
Subject: RE: Topband: high SWR problem with RG214
To: "'sasas asasas'" <tzitzikas_ee@yahoo.com>
Date: Thursday, October 21, 2010, 8:19 PM
Hi,
2 mtrs RG214 has capacity of obout 180pF.
What you have done with this coax is you connected a capacitor(180pF) from
antena feed point to the ground , before your matching series capacitor !
Put the matching capacitor between antenna and coax feeder.
GL!
Drago,S59A
-----Izvirno sporočilo-----
Od: topband-bounces@contesting.com [mailto:topband-bounces@contesting.com]
Namesto sasas asasas
Poslano: 21. oktober 2010 18:27
Za: topband@contesting.com
Zadeva: Topband: high SWR problem with RG214
Hi. I have a transmitter 500w. I was operating my transmitter with low SWR
(250w FWD power and 0,5w RFL power). The antenna's match system is only a
series variable capacitor 0-500pf. With this variable capacitor i can
achieve very low SWR.
My antenna (the feed point i mean) was starting inside the transmitter's
metal house, and i have some problems with my pll's lock and the modulation.
So i decide to move the antenna's feedpoint out of transmitter's metal
house. To achieve this i used about 2 meters of coaxial cable RG214 between
the variable capacitor and the antenna's feed point. After this change i
have very high SWR !. With 25w FWD power output, i have 1w RFL power! What
do you think is the problem? The 2 meters RG214? I am thinking that these 2
meters of RG214 cable are putting paraller capacitance between the feed
point and the ground system. How can i zero this capacitance? If i put a
varable coil in paraller with the RG214? Or it is wrong to use RG214 between
variable capacitor and antenna's feed point and i must use RG214 only
between transmitter and variable capacitor?
thank you
_______________________________________________
UR RST IS ... ... ..9 QSB QSB - hw? BK
_______________________________________________
UR RST IS ... ... ..9 QSB QSB - hw? BK
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