Astec AA21660 power supplies can be modified to give 13.8V / 24A.
They are specified to 24A @12V and 27A @5V, with 400W max continuous power. It is used in various Engenio (former LSI Logic) storage products, which are OEM-ed by many companies: IBM (TotalStorage DS4xxx and DS5xxx line), NetApp etc. The IBM FRU is 19K128.
The following mods change the overvoltage protection to 14.4V, and set the voltage to 13.8V.
Threw a wire on a palm palm tree, stretched a counterpoise on the ground, tuned it, and made the first CW QSO on 40m with Zygi SP5ELA. So next I’ve tried to tune the antenna on 80m, and the uSDX transceiver failed with a short circuit.
It seems that the smd PA transistor died on 80m (it also dies on 10m). Fortunately I’ve had two IRLML2060 transistors with me, but no soldering iron and other tools.
So is there any hope that i will be able to make more than one QSO?
I have traveled to Crete / SV9 in July 2021 for vacation. I’ve spent vacation in Greece many times. This time i brought a shortwave transceiver with me to see if amateur radio will be compatible with a family vacation.
One of my new year’s resolutions for 2021 was to make some contacts via the QO-100 satellite.
This would normally require equipment like an ADALM-PLUTO or other transmit-capable SDR, transverter, power amplifiers etc. This is necssesary for SSB and other modes, but for CW it should be much easier and cheaper.
I’ve added two etherify articles to the Soft TEMPEST series, one showing an exceptionally strong signal radiated from a raspberry pi 4b, and another showing that regular ethernet hardware can also be used.
I’ve always wanted to make a Moxon antenna, but didn’t have an excuse to do so. Recently i needed a very lightweight directional antenna for Etherify with not so much gain, but considerable F/B, so i finally had the excuse i needed.
To transmit CW on the Kenwood TR-9000, TR-9130, TR-9300, TR-9500 (and maybe other) transceivers one has to hold the PTT on the microphone (or on the optional BO-9 base) and only then transmit using the KEY. For some reason the Kenwood thought this would be an excellent idea.
This is a simple external semi-BK circuit implementation, so that you can just press the key to transmit. No modifications inside the radio are necessary.
The circuit is connected to the STBY (2.5mm jack) and KEY (3.5mm jack). Connect the key to the CW KEY terminals. To increase the time make the capacitor bigger, currently it is 3000uF (3x 1000uF in parallel). The diodes are any silicon diode like 1N4148, 1N914, 1N4001 etc.
Keep in mind that the capacitor is charged to 8V, so that the key has temporarlily 360mA flowing thorugh it. No problem for a straight key, but it might be an issue with some electronic keyers.