The Palstar AT-AUTO is a fully autonomous, fully automatic impedance matching network (an antenna tuner) that employs an embedded microprocessor to position a conventional roller inductor and a split-stator variable capacitor. It provides continuous coverage tuning from 1.8 – 54 MHz (including MARS, DoD, and commercial frequency bands, etc.) and is rated for 1500 W continuous carrier operation. The AT-AUTO is quiet and reliable, and with its industrial-rated stepper motors, provides a superior impedance match to that provided by the loud clanking boxes of relays provided by the competitors.
The tuner continuously measures forward and reflected RF power. As long as the SWR is below a user-selectable threshold, the AT-AUTO provides a “Good Match” cue in the Liquid Crystal Display (LCD) and takes no further action. Whenever the SWR exceeds the “Tune-Start” SWR, the AT-AUTO then counts the RF carrier frequency, looks up previously stored Inductor (L) and Capacitor (C) settings for the frequency of operation and then repositions L & C to the recalled settings. If the SWR is still excessive, the AT-AUTO automatically begins tuning, and provides user prompts during the entire process via the LCD. Once a good match is found, the new match settings are stored in memory for subsequent recall. The default behavior is highly customizable to suit individual needs.
The AT-AUTO is also able to obtain frequency information via the radio’s serial data port (for these compatible radios so equipped). By doing so, the AT-AUTO instantly follows frequency changes (VFO adjustment, etc.) and immediately recalls and sets the L & C for the new frequency – without the need to generate an RF carrier! The recalled match should provide an excellent SWR so that when RF is finally applied, subsequent tuning will not be necessary. While the serial port is not necessary for automatic tuning, this “Smart Mode” of operation greatly speeds the entire process of changing frequencies.
I have just enough space to rackmount everything. Considering I also have rear rack rails, some less important items can be mounted from the rear. This is all about the ergonomic layout. I may even build some breakout panels for the antenna and audio connectors. I’ll be using a combination of 2U and 3U rack shelves (special thanks to the folks at Gator Rackworks!) I had to go 3U for some shelves in order to get a useable depth. Most of the radio gear will sit on shelves.
The current layout plan (from top to bottom):
ROTOR SHELF 4U
AT-AUTO HI 4U
AT-AUTO LO 4U
2M RADIO / TNC 1U
FLEX VU5K 6U
FLEX 6300 2U
FLEX 6700 2U
AC POWER 1U
PC#1 W7 4U <<< DESKTOP
PC#2 W10 4U
PC#3 SERVER 4U
ASTRON RS-70 4U
I need the radios and amplifier close to the desktop, placing other ‘less touched’ items either down below or up above. I think the ergonomics are OK at this point.
Before I can start building I have to empty the shack so I can remove all the dust. I have a significant dust problem. And the problem was most apparent as I swapped out the cases on the two production PC’s. Choking on dust.
The plan is to empty the room, and mitigate the dust. I plan to use an air compressor to blow off the dust that’s embedded in the stucco-like ceiling, then, I’ll thoroughly vacuum before having the carpet steam cleaned. Going forward I will employ an oversized HEPA filter in the radio room which will run 24/7 to capture all particulates and hopefully eliminate or at least vastly improve my dust problem.
The PC monitors are in place, look great, and exhibit no RFI at full output. The operating position is fully tested and ready for the contest.
I decided to try a 4K UHD monitor and selected the LG 32UD59-B (top) and it looks fantastic!
The few minor problems that remain will be addressed after the contest. For all intents and purposes, this project is complete. I may decide to upgrade the PC monitors in the near future, but for now the station hardware is complete.
Now it’s time to OPERATE!
-P.S. 02-23-18: I was doing some testing with the data cable connected to the recently installed AT-AUTO, and the tuner works as expected. I was able to work KB3RHR and K7KPH and both gave me great reports.
The AT-AUTO arrived safe and sound in spite of a loose packing job. By the time the box arrived it was all “rounded out”. This is what happens when you use a light gauge box for a heavy item, and the item is ‘loose’ inside. Yep, you guessed it…the box was full of styrofoam ‘peanuts’. Hey, it was a happy ending, the tuner works as expected so far. There are a couple of cosmetic differences that I imagine have to do with the different production runs. Overall I am happy with this purchase. More info available at the Kessler Engineering website.
AT-AUTO Data Cable
The data cable was scheduled to arrive today, but did not. So I say ‘so far’ because I could not test the data port tonight, but I’m sure it won’t be a problem. The coax cables arrived on time because the eBay seller shipped them on Saturday! Hat’s off to “WifiExpert” on ebay! Highly recommended!
The AT-AUTO was one of the last pieces I needed to complete my 2018 station overhaul. I now have near perfect SWR everywhere. The Expert 1K-FA is a great amp, but the internal tuner only matches up to 3:1 SWR. I had issues with antennas being out of range of the 1K-FA internal tuner, and resolved ALL issues via the AT-AUTO.
Fully Automatic Tuning – QRO
I cleared the memory and trained the tuner on all bands, then did the same with the tuner in the amp. The result is a perfect match on any frequency, on any antenna, and tuning is fully automatic! I’m very happy to have this in place for the ARRL contest.
The AT-AUTO ‘s will follow the active TX slice on the radio, and enable the operator to concentrate on the work, and not be concerned with making errors when changing bands etc.
The Expert 1K-FA does all the antenna switching automatically. Fully automated, and carefully programmed, the 1K-FA greatly reduces the chance of user error. The K6HR Contest Station Block Diagram makes this SO2R setup a bit easier to understand.
The transceiver is a FlexRadio 6700 featuring two Spectral Capture Units. I utilize the two SCU’s as “two radios”, each with its own amplifier, tuner, and antenna. I designate ANT1 as the Mosley TA-33-JR-NW (for all HF bands 20 meters and above) and ANT2 as my 130ft Height Compromised HF Dipole for frequencies on 30 down thru 160 meters. Low SWR across all amateur bands!
The cool trick is the operator can move freely through the bands and operate at will via either radio. The 1K-FA’s foolproof switching ensures the TX radio will get the correct TX antenna every time. The second radio, in every case will be connected to the wideband RX loop antenna.
Data Driven via Flex USB
The Expert 1K-FA and the Palstar autotuners operate based on frequency data received from the radio. The 1K-FA and the AT-AUTO autotuners follow the radio in realtime as the operator changes frequency.
The operator only needs to turn the ‘tuning dial’ and press the PTT!
LP-500 Station Monitor
I have installed the LP-500 station monitor with 4 sensors. You could say it takes the guesswork out of getting good reports!
Leveraging the four sensors of the LP-500 Digital Station Monitor, I can ensure both amplifier channels are operating at full output, with the lowest SWR, and best linearity at all times.