GE,
...but it will increase the PD inception level due to the high epsilon r and so
you can run more power (voltage) ;-) You should use this advantage ;-). But be
aware that the increased current does not melt the ice ;-)
So power should be a function of the outside temperature which could be
regulated with a temperature sensor that is controlling the duty cycle of the
input signal or the DC-voltage of the PA by a class h modulator ;-)
73, Stefan/DK7FC
________________________________
Von: [email protected] im Auftrag von Graham
Gesendet: Di 12.01.2010 22:18
An: [email protected]
Betreff: Re: LF:Ice and frost on 600m antenna
Pete,
The ice will be pure water and may not conduct .. will have some capacity
implications though !
G ..
From: M0FMT <mailto:[email protected]>
Sent: Tuesday, January 12, 2010 1:51 PM
To: [email protected]
Subject: LF:Ice and frost on 600m antenna
Hi LF Group
In an attempt to calculating the effect of ICE (Haw frost) on my antenna I get
these results.
With a wire diameter of 1.5mm flex weave, it comes out to 1.1 amps for 60 watts
RF applied. This is confirmed crudely by observing a pair of car festoon lamps
(12Vx0.5A each) in parallel in the antenna up lead glowing to full brightness.
With an estimated increase in antenna wire diameter to 10mm caused by the Haw
frost I did not notice any change in antenna current by this method.
Running the calculation through using a 10mm wire I get 1.2 amps and again to
an absurd size of 20mm diameter there is virtually no increase in current.
The recent WX at this location has had no noticeable effect on the antenna. If
it did I would suspect leakage through a dodgy insulator at the top of the
inverted "L" up lead.
The type I use is a deeply ribbed glass insulator about 8 inches long.
73 es GL petefmt
<<winmail.dat>>
|
