Interfacing the Hardrock-50 HF amplifier to the Hermes-Lite 2

Since several months ago, I'm operating my HF station "remotely" from another room in the house. The station consists of a Hermes-Lite 2.0 beta2, a Hardrock-50 HF amplifier, and an outdoor MFJ-993BRT antenna tuner. My plan is to operate all of this from a laptop with ethernet connection from anywhere in the house.

The Hermes-Lite poses no problem, since it is always controlled by ethernet only. However, I need to be able to operate the Hardrock amplifier remotely: I need to change the bands, which is usually done via buttons on its front panel, and to check the output power and SWR, if only to be sure that the antenna tuner has found a tuning solution. This is usually done by looking at the Hardrock front panel display or by looking at a Diamond SX20C power/SWR meter that I also have installed in the shack.

I have taken advantage of the holidays to finish making all of this controllable by ethernet. Here I describe my solution.

Continue reading "Interfacing the Hardrock-50 HF amplifier to the Hermes-Lite 2"

Calibrating the S-meter in Linrad

In a previous post, I talked about the GALI-39 amplifier kit from Minikits. Here I will describe the procedure to calibrate the S-meter in Linrad (or another SDR) using this amplifier or any other amplifier with a known NF and an uncalibrated signal source. Leif Åsbrink has a youtube video where he speaks about the calibration of the S-meter in Linrad. However, he doesn't use an amplifier, so I will be following a slightly different procedure.

Continue reading "Calibrating the S-meter in Linrad"

Building the GALI-39 amplifier kit from Minikits

The GALI-39 is a DC-7GHz MMIC amplifier from Minicircuits. This device has a gain around 20dB and a NF of about 2.4dB. The nice thing about MMICs is that their input and output impedances are matched to 50Ω, so it's quite easy to work with them. Minicircuits makes many MMIC amplifiers suiting different needs, but unfortunately their products are not so easy to get in small quantities.

Minikits.com.au is an Australian store that sells Minicircuits parts in small quantities as well as many interesting RF kits. I needed some RF amplifier having a known NF to do some signal level calibrations, so I ended up ordering the GALI-39 amplifier kit from Minikits. This kit includes just the GALI-39, a PCB and the handful of SMD components you need to bias the amplifier. At 22AUD, the price of the kit is about right and buying the kit instead of just the GALI-39 saves me to do the shopping for the assorted SMD components and using the PCB instead of botching some circuit is always nice, because the PCB uses microstrip transmission line (but the substrate is regular FR-4). Here I have a look at what is included in the kit (I've been unable to find a complete list on Minikit's web).

Continue reading "Building the GALI-39 amplifier kit from Minikits"

Band switching with the Hardrock-50 HF amplifier and the FT-817

The Hardrock-50 HF is a very nice kit for a 50W amateur HF amplifier covering the 160m through 6m bands. It supports interfacing with the FT-817. With the proper cable, the amplifier can be connected to the ACC jack on the FT-817 in order to do PTT keying and read the BAND DATA signal from the FT-817 to select the proper band in the amplifier's low pass filter automatically. The connections required are shown in the Hardrock-50 Tech Site. Yesterday, I prepared the cable to interface my amplifier to my FT-817ND. However, I have found a problem in my amplifier that prevents automatic band switching from working properly. Apparently, this problem has been fixed in the newest units and can be fixed with an easy modification in the units which are affected.

Continue reading "Band switching with the Hardrock-50 HF amplifier and the FT-817"