Ham Radio - Revisiting the PA0RDT Miniwhip active RX antenna. 

I did in a previous video back when I first got it.

The circuit boards I have seen are all powered through coax. I have not seen preamp boards with a V_in tab. Therefore, let me describe what to look for on your preamp board so that you can determine whether your unit can operate with power through coax. Pause the video at 0:47, switch RU-vid's video quality to 1080p, and look at the right end of the "low-noise broadband amplifier." Just above the coax connection, you can see a small black "can" labeled L1. That inductor blocks RF and passes DC from the coax to the amplifier, while capacitor C3 blocks DC and passes RF from the amplifier to the coax. If your unit can operate from power over coax, it must have those two components. Many mini-whip preamps have two inductors, in which case the inductor connected to the coax may be labeled L2. If your preamp has a V_in tab, it almost certainly is connected to the end of the inductor that is not attached to the coax.

Yes. I've done it back when I first played around with it.

I've done that in a previous video, back when I first got it.

Current doesn't work like that. A power supply may be capable of providing 5 amps of current, but the circuit will only draw as much as it requires.

@@loughkb I sort of figgered tha, but doesn't harm to ask. I have a new active powered antenna for receiving SDR signals on computer. Plugged the 12 V DC power supply in, and the first capacitor ( just before the Z diode) in the circuit, and his is showing signs of heat by smoking and a small burn mark. Must be Zener was shorted when circuit made up at factory. Getting very high ohm readings in both direction, not just in one direction. Appears there's a short to Gnd..

BTW, you are doing the antenna a great disservice by mounting it beside the body of the RV. Mount your other antennas 3 inches away from the body of the RV and you will see their performance go to hell, too.

It's above the body of the RV, not beside it. At the top of the tube, above the ladder. And after a bit more use, it's working better than I thought initially. Maybe not the best it could, but it's fulfilling the intended task. Providing me an RX antenna that's always available.

I've been able to draw sparks from several types of antennas when there's a charge in the air. Usually when storms are passing within a few miles. I disconnect my wires when there's weather moving through. It also seems to happen more often at higher altitudes since you're closer to the upper layers of the atmosphere.

@@loughkb I was just in good old pancake-flat Southern Florida. But that was a static wake-up call for sure.

@@unklewink Florida, the lighting capitol of the states. You'll get a lot of that charge there. I've been in Arizona for awhile and in about a month, monsoon storm season starts. I'll have the antennas disconnected more often than not.

@@loughkb I have felt the wrath of lightning. I was disconnecting a 450 ohm antenna feedline from my rig to protect the rig, as a thunderstorm approached. Lightning hit a neighbor's tree at that moment. Knocked me on my... you get the idea!

Yes, made a small difference.

I hadn't looked into that. I didn't know the malahit would provide I/Q signals over USB.

@@loughkb from what I understand in windows world the malahit can be controlled and will work with the computer via the USB connection. I'm not familiar with the malahit completely yet. It was given to me by another ham. He said he wasn't having any luck with it and was tired of playing with it. It is a chinese clone.. I opened it up and after some online research discovered it was missing a FRAM chip FM25W256-G. This chip is looked for by the upgrade firmware and if it doesn't find that chip, the software stops in a loop looking for it and it acts as though it is bricked. I bought a few of those chips and installed one in my malahit and upgraded the firmware to 1.10a and it worked. I know the malahit requires the upgrade software to make it talk through the usb cable. I have a raspberry pi 3b at my station and I pieced together my OS starting with debian buster command line, the lite version and then added the rest of the parts to customize it a bit according to some directions I found online. I added a GUI and a bunch of ham software. It recognizes the malahit being connected as near as I can tell but it's not showing up on the list in gqrx. I'm not sure if it's a driver issue or something else. I may try one of the ham specific OS for pi that you reviewed.

@@kd5inm Ok, I think I follow. Through the USB connection, the radio creates an audio device. Any program that can record audio should be able to select it as an input. For example, FLDigi for decoding various digital HF modes. It also creates a serial port device and can use that for basic rig control through programs like FLRig. GQRX is a program designed to take in I/Q signals from SDR receivers like the airspy, sdrplay and such. Where the hardware is just acting like a digital sampler for RF and the software does all the demodulating stuff. GQRX is the radio, the hardware is just an RF sampler. So two different things. The malahit does all the sampling and demodulation already, only outputting audio.

@@loughkb OK, I understand. How were you getting GQRX to work with the malahit? Or did you have GQRX connected to another device? I was thinking you had the malahit connected for GQRX. Or am I mistaken? I appreciate your patience and kind instruction on this as well as your videos. I have been watching and subbed for many years.. De KD5INM

@@kd5inm I don't remember using the malahit with gqrx. What did you see that gave you that idea? Which video? I'll go look at it and attempt to explain what's going on.

An Airspy discovery HF+

@@loughkb Welp i have seen it everywhere better get out my wallet A low of 9khz is very very good

I sold the house almost three years ago when I left in the RV. I earn my survival via these youtube videos and the support of my patreon folks.

Wow! Glad it all worked, keep the videos coming, they're always good to watch.

It's presently living atop the metal ladder on the back of my RV. Working pretty well. It's an always available RX antenna that takes no time or effort to put up.