- The connections from the dipole support cables to the dipoles
was found to cause arcing/corona with the 5MHz dipoles (this was
found during the mar17 hf campaign).
- insulators were installed on all support cables for the 5 mhz
- the 04may17 hf test was to see if we still had arcing/corona,
What we did:
- The 430 xmiter was brought up around 10:00
- single beam, ch za =0 , ch -> echotek [5.5,9.5], ch ->
- clp run the entire time.
- The hf mesh was set to the 5 MHz position.
- 10:00 start to bring up the hf tx
- 10:16 lost network communications to the hf control building
- not able to monitor the power levels
- maintenance has shutoff the power the the engineering
building (in maintenance).
- Unfortunately the hf control building had its ethernet going
through the switch in this building.
- hf total output was sitting at around 100 KW. during this
- 11:00 network communications back, but trouble communicating
with spectrum analyzer (anritsu)
- problem was the rightmost ethernet jack behind the
desk was bad..
- 11:xx start to bring tx up farther. Lots of arcing from
tx 5. had to bring it down.
- 12:04 54 KW each tx (except tx5)
- 12:45 to 13:02 tx 430 off. Went down to check for arcing
under the dish.
- 13:01 anritsu hung up again
- 13:10 hf off for 5 minutes
- 13:15 rf back on
- 13:23 restarted anritsu.
- 13:46 hf off to work on tx 5 problem. 430 continues to run
- 14:50 bring hf tx back up (tx 5 still down)
- 15:00 bring up tx5..
- running at 6*80Kw = 480KW output power.
- 15:18:08 turn rf off
- 15:22 auto toggle 1sec on 2 sec off
- 15:30 back to cw to get power level measurement
- 15:35 hf off, did spectrum check with usrp.
Plots of output
and drive power:
The plots show the hf drive and
output power for the test (.ps) (.pdf)
- The page has 3 frames:
- each color is a different transmitter (1 through 6).
- top frame: rf power (in dbm) measured at the output of
the rf coupler.
- middle frame: the same output power, but displayed in KWatts
- bottom frame:
- The synthesizer drive amplitude used
- The dashed green line shows when the rf was on
- 2nd frame:
- before we went down to work on tx5 (at 13.8) we were
transmitting 5*75 KW (tx5 was off)
- When we came back up, each of the 6 tx were transmitting gt
80 KW.. about 485 KW total
- The reflected power read from the meters on each Tx were each
less than 3KW
Plasma line movies
Plasma line movies were made from the echotek
data (433 to 441) and from the usrp (25Mhz bw at 430).
to the movies
The movies were limited to:
- std movies:
- +/- 10 Mhz usrp, 433-441 echotek
- high res movies
- usrp: 433 to 435.6 Mhz, 100 to 214 Km
- You see the enhanced plasma line in the eregion (starting
- You can see the layer grow from 4 Mhz up to 5.125 Mhz.
- echotek: 433.2 to 437.5 Mhz, 105 to 340 km
- you can see the enhance plasma line around the natural
plasma line (about 220km ) until about 11:40. After
that the eregion layer grows and the enhanced plasma line
moves down around 120km
- We saw images of the plasma lines at +/- the hf frequencies.
- This would occur if the 5.125 Mhz was getting into the ch 400
MHz Local oscillator.
- Tx 5 had an arcing problem. It goes fixed around 15:00. One of
the contacts on the PA tube was causing the problem.
- We ended up transmitting 80*6 KW = 480KW from 15:00 to 15:30
- The reflected power during this time was less then 3KW (30 on
the meter) on each Tx.
- Looks like the old support cable connectors were causing the
nasty reflected power we had been seeing.
- Data taken with the 430 MHz Tx showed a strong e region layer
where we were getting an enhanced plasma line.
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