Hello to all,
Thanks to all that replied to my request.
Based on the information I have received :
VOLTAGE = SQUARE ROOT (POWER x RESISTANCE)
CURRENT= SQUARE ROOT (POWER / RESISTANCE)
With a 50 OHM LOAD.
POWER---------100-----1500-----2500---WATTS
1:1 SWR
CURRENT------1.4-------5.5--------7----- AMPS
VOLTAGE-----70.7------274-------354
2:1 SWR
CURRENT------2.8--------11--------14--- AMPS
VOLTAGE------142-------548-------708
3:1 SWR
CURRENT-------4.2------16.5-------21--- AMPS
VOLTAGE-------212------822-------1062
The 3:1 SWR should be considered as the worse case with
some type of antenna system failure. The 2500 watt is used
because some amps can put out this amount of power. If an
operating error is made the system should be designed to
handle it.
Reviewing published information on vacuum relays I
concluded the higher frequencies degrades the current
and voltage capabilities of the relay. This factor dose
not seem to be liner and varies slightly between relay
companies.
FREQUENCY-------FACTOR
60 Hz-------------------none
2.5 MHz---------------1.2857
16 MHz------------------2
32 MHz------------------2.57
The resultant is obtained by dividing the 60 Hz value
by the factor in the frequency range the relay will be
used in.
Vacuum Relays
Jennings RJ1A
FREQUENCY----VOLTAGE----CURRENT
60 Hz-----------------3.5 K-------18 AMPS
2.5 MHz--------------2.5 K-------14 AMPS
16 MHz---------------2 K----------9 AMPS
32 MHz-------------1.5 K----------7 AMPS
Kilovac HC-1
FREQUENCY------VOLTAGE---CURRENT
60 Hz------------------3.5 K-------25 AMPS
2.5 MHz---------------2.5 K-------14 AMPS
16 MHz------------------2 K--------9 AMPS
32 MHz----------------1.5 K--------7 AMPS
A very popular non-vacuum relay is the NAIS JW1FEN.
I have this relay in use at my station for antenna switching.
It is used at the 1500 watt level and has performed without
any problems for quit a few contests.
These are the results based on the degrading factor used for
vacuum relays.
Nais JW1FEN
FREQUENCY-------VOLTAGE--------CURRENT
60 Hz-------------------250--------------10 AMPS
2.5 MHz----------------194--------------7.8 AMPS
16 MHz-----------------125---------------5 AMPS
32 MHz ------------------97-------------- 4 AMPS
Requirements based on formula are far from actual
station component usage.
Are we just lucky ?
Is it just a matter of time to a relay failure?
Is the duty cycle for the type of operation be a factor?
Any Comments Please
Rich AA2MF
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