HI
GOOD DAY TO ALL.
NEW
YEAR GREETINGS FROM INDIA.
?Today(01.01.2021) I measured the SWR of my
antenna system using ANTUINO ANALYZER. It is observed ?that there are very wide variations in the SWR
values when the antenna is connected direct to the BITX rig (barefoot) and when
connected through the linear amplifier(PUTTING THE LINEAR IN SWITCHED OFF
CONDITION). The relevant details are as below
??
I am using uBITX V6 with a linear amplifier driving
?about 5w into linear amp.
??
Linear amp draws about 70 W power.
??
I am using inverted VEE antenna for 40 m and 20 m
band ?with common coax feeder.
??
The linear amp has got provision such that when
it is switched off, the antenna and ubitx rig are ?connected so that the output from the barefoot
ubitx rig is getting pushed out to the antenna. This facilitates easy operation
for changing QRP TO QRO or vice versa without unscrewing and screwing the
connectors but by simply switching the linear on or off
? With the above set up I made the observations
on SWR using Antuino and the observations are as below
LOWEST
SWR VALUE AND CORRESPONDING FREQUENCY
- THE ANTENNA CONNECTED DIRECT TO THE ANTUINO ANALYZER ?
|
FREQUENCY? IN MHZ
|
SWR
|
?
|
|
7.140
|
1.5
|
?
|
|
14.250
|
1.2
|
?
|
?
??????? 2.THE
ANTENNA CONNECTED TO THE ANTUINO ANALYZER ?THROUGH THE LINEAR
???????????
AMPLIFIER ?BUT THE LINEAR IS IN SWITCHED OFF CONDITION
|
FREQUENCY? IN MHZ
|
SWR
|
?
|
|
7.290
|
1.1
|
AT
7.140MHZ, SWR 1.4
|
|
14.100
|
4
|
AT
14.000MHZ SWR IS 5.8
AT
12.060 SWR IS 2.6
|
?
i)In the 7 MHZ band, if the
linear is in series with TX ?and the
linear IS IN SWITCHED OFF CONDITION , the SWR gets good improvement but at
higher frequency ( outside ?the band)
ii) In the 14 MHZ band, if the
linear is in series with TX ?and the
linear IS IN SWITCHED OFF CONDITION, the SWR value rises ?up drastically (5.8 AT 14.000MHZ)
?As such I like to know the reason for the
above SWR variations and to get guidance to bring the SWR values within 1.5 in
both bands and in both linear on and off positions.
?. ???I
appreciate, any one, kindly throw some light on the above and give some tips
??
Thanks a lot in advance
??????????????????????????????????????????????????????????????????????
???With 73
?
?????????????????????????????????????????????????????????????????????????MUTHU?
???????????????????????????????????????????????????????????????????
???????VU2LMN
????????????????????????????????????????????????????????????????????????
+919443114779
