Sunday, January 20, 2019

Increased functionality of Hardrock-50 with autotuner option installed


Tuning solution results on 6 meters


My HR-50 is now complete with the increased functionality that comes from having the $179 autotuner (ATU option) installed. This includes:

  • Auto-tuner capability
  • 60m capability
  • QRP Mode

True to its name, the ATU tunes antennas that have up to a 10:1 SWR ratio. The HR-50 requires a manual push of the Mode button in order to begin a tune cycle. There is no provision to have the tuner initiate a tune cycle on its own if, for example, something happens to the antenna while operating. However the LCD display will show an increase in reflected power if this occurs, prompting the operator to initiate a tune cycle or to investigate the antenna/feedline issue that caused the change.


Start-up screen now shows ATU presence & firmware version
Once a solution is found, the parameters are saved so that a new tuning cycle is not required when returning to a previously tuned antenna-band combination. Also, the ATU's relays are non-latching - power to the amp must remain on even if the amp is being used only as a tuner (see QRP Mode, below).

The ATU works as expected, easily and quickly tuning my triband Yagi on 12 and 17 meters. I have a PAR Omniloop for 6m mounted to a 10-foot pole on my chimney. Its direct SWR on 50.313 MHz is 2.2:1 - with the tuner activated it becomes 1.2:1.

On 30-80 meters, I use an 80m dipole fed with about 120 feet of ladder line. Depending on the band, its SWR can be 25:1 or higher. The ATU will not tune this antenna nor is it designed to; instead, I tune to within the ballpark on my Palstar AT2K (I have the dial numbers posted near my desk) and can then let the Hardrock 50's ATU do the rest. This still saves time since I no longer have to be exact on dialing in the perfect values on the AT2K's 3 controls.

Without the autotuner installed, the HR-50 lacks 60m capability - the band is not selectable with the
Receive screen showing QRP mode selected
band switch. With the autotuner installed, a 60m filter is now available as is selectability. On my HR-50, 2 watts of drive on 60m produces an output of 50 watts (14VDC supply).

In QRP Mode, the amplification function is turned off but autotuning of the antenna and display of forward power is retained. The HR-50 essentially becomes an outboard autotuner with graphical display of power. And, if you decide you want it, 50+ watts is available at the push of a button.

Receive current when used in QRP Mode with the ATU relays energized to maintain a match is 250 mA.

I'm looking forward to using this amplifier from the field with KX2 and my PAR End-Fed antenna for 20, 30 and 40 meters. That will likely be next weekend during the Winter Field Day.

Transmit screen when in QRP Mode
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