Gary @N8DMT
n8dmt.mastodon.radio.ap.brid.gy
Gary @N8DMT
@n8dmt.mastodon.radio.ap.brid.gy
Amateur Radio Extra, Maker, Product developer, Wireless/RF/Antenna guru / electronics consultant, LabVIEW, RTL-SDR, ADALM Pluto, GNU Radio, FCC testing. Location […]

🌉 bridged from https://mastodon.radio/@n8dmt on the fediverse by https://fed.brid.gy/
US Coast Guard aircraft executing a search just south of Key West Florida. Additional assets joining in now.
December 6, 2025 at 1:22 PM
Found another ZFL-2000 amp in the lab stock - but this one is tagged as “BAD”. Will retest and if actually defective, will set aside for disassembly during next snow day. Curious to see if there is a part number / label on the back side of that 12-pin circular Mod-Amp case. #rfamplifier #smokeletout
December 5, 2025 at 3:33 PM
What is inside a Mini-Circuits ZFL-2000 RF Amplifier? Had a few minutes to take a quick look inside one of these RF Amps. Didn’t learn much, and was surprised to see a fully-cased (pins) amplifier module inside. Would take a lot more effort to disassemble […]

[Original post on mastodon.radio]
December 5, 2025 at 1:59 PM
Completed a few tests on the 2.4 GHz RF Equipment (RFE) components for the single-band Pluto transceivers. TLDR: All looks good and ready to continue evaluating controller software. Details at the qsl.net blog. #hamradio #sdr
https://qsl.net/n8dmt/24-ghz-pluto-rf-equipment/index.html
November 26, 2025 at 9:21 PM
RF equipment setup complete for first low-power 2.4 GHz test using Remote SDR and Pluto SDR. Waiting for the afternoon to find/retrieve the second RaspberryPi-5 computer needed for the second transceiver controller. (Have moved multiple times with re-boxing […]

[Original post on mastodon.radio]
November 23, 2025 at 3:01 PM
Here is the system drawing showing the local laptop PC with headset and the remote computer & RF equipment group (Raspberry Pi 5, Pluto SDR, and transmit/receive amplifiers and filters leading to the antenna). Ideally, the remote equipment is located VERY […]

[Original post on mastodon.radio]
November 21, 2025 at 9:50 PM
Slow Work Day: Let’s sort ferrite! Made a quick ferrite material sorter using NanoVNA-H4 and a two-turn test loop. Ended up finding at least four material types. Now labeled in separate bags and ready for (easier) future use!
#hamradio #emiemc #sortalltheparts
November 17, 2025 at 8:50 PM
Have you seen video on the DIY capacity hat for a vertical antenna whip? Link below for one ham’s approach. Have purchased some 24” zip ties and found the lab stock of copper tape. Interested to see how this works on my 17’ SS-17 whip antenna!

With the cooler […]

[Original post on mastodon.radio]
November 14, 2025 at 9:19 PM
The 3/8-24 antenna ground-isolator/connector test box is completed. This simply connects or disconnects the lower ground stake connection to the upper counterpoise / coax-feed and vertical whip assembly. It’s easy to have the ground stake connected with the […]

[Original post on mastodon.radio]
November 14, 2025 at 8:58 PM
I’m sure there is a project in here somewhere: Parts for an experimental ground isolator for a 3/8-24” vertical antenna mounting system. The box goes in between the ground spike and radials/coax-feed/vertical-whip. The switch will open or close the ground […]

[Original post on mastodon.radio]
November 12, 2025 at 8:44 PM
A follow up post on the DIY RF Comb Generator. TLDR: It works even better when mounted to a small board with SMA jacks! Nice quality combs up to over 1 GHz! Details over at the qsl.net blog. #hamradio #testequipment
https://qsl.net/n8dmt/diy-rf-comb-gen-test/index.html
November 11, 2025 at 1:25 AM
DIY RF Comb Generator for less than $1.00? After evaluating the mil-spec Herotek comb generator module and Pluto SDR clock source combination, decided to try out a low cost alternative for generating combs. With an on-hand SI5351A clock source, added two […]

[Original post on mastodon.radio]
November 10, 2025 at 3:32 PM
Finished up testing of what looked like an RF amplifier module but was really a comb generator. TLDR: It works! Now have picket-fence RF signals! Details in two posts over at the qsl.net blog site. #hamradio #testequipment […]

[Original post on mastodon.radio]
November 8, 2025 at 4:06 PM
Getting the lab organized a-bit more: Printed out a data sheet for a pair of Narda RF couplers. Have both couplers back in the same storage package again. What is the RF Geek equivalent of the old hammer-nail saying?

When all you have are RF couplers […]

[Original post on mastodon.radio]
November 6, 2025 at 9:22 PM
Random RF Component Find #308: Herotek GCA640-258 RF comb generator. Was stashed in one of the garage lab boxes. Needs cleaning! This appears to be a 640 MHz input comb generator that will output multiples of that frequency up to ~ 18 GHz. Includes a […]

[Original post on mastodon.radio]
November 4, 2025 at 9:36 PM
2M FT8 Monitor: Setup the IC-705 with 16’ of RG400 coax feeding a DIY 2 Meter halo perched on top of the office closet door. Using SDR-Control on the iPad for FT8 decode. Will monitor 144.174 FT-8 to see if I can hear anything (only seeing always-there power […]

[Original post on mastodon.radio]
November 2, 2025 at 3:41 PM
Testing the new 33 cm Pluto SDR controlling software: Have basic RX/TX working and tested on FM mode using a local (second Pluto) SDR linear translator “repeater” controlled by GRC. Notes on using F1ATB’s Remote SDR SW over on the QSL.net website (3 postings) […]

[Original post on mastodon.radio]
November 1, 2025 at 8:05 PM
Testing a RF Limiter with a Yaesu VX-8DR HT: Was able to find 4 RF limiter candidates for use in a 902 MHz full duplex transceiver and tested one unit’s limiting function using L2 TX Po at 446 MHz. TL:DR, the tested limiter works as hoped! More information and […]

[Original post on mastodon.radio]
October 23, 2025 at 8:15 PM
Thinking about a 902 MHz transceiver based on the ADALM Pluto SDR using a set of printed circuit board filters and a RF circulator to combine the TX and RX paths together at the antenna (supporting full-duplex comms). Measured two sets of 902 MHz circulators […]

[Original post on mastodon.radio]
October 21, 2025 at 8:34 PM
Today’s Music Festival Attire: A green shirt with a T-Rex dinosaur with the statement “Make Billionaires Extinct”. Background is a ringed planet and stars.
#makeastatement
October 18, 2025 at 11:17 AM
KK7B 144/902 converter LO update: Setup the HP1121A RF probe to walk down the LO lineup and found a gain stage with only +2 dB gain. The resistor to VCC is 560 Ohm instead of 100 Ohms as the other amp stages have installed. Will find a 100 Ohm resistor and […]

[Original post on mastodon.radio]
October 13, 2025 at 5:47 PM
A few additional thoughts on the KK7B 144/902 translator boards: 1) Add connectors to the RX and TX filter chains on a bare board and use it as a Pluto SDR front-end on 902 MHz. With pi5 & Langstone SW + RX LNA, TX PA and T/R switch yields low-cost 902 […]

[Original post on mastodon.radio]
October 12, 2025 at 3:08 PM
The converter’s oscillator/multiplier stage basically works (although a-bit low on power level). Board draws ~208 mA at +12V which seems reasonable for the number of active devices installed. Frequency looks good at 758 MHz monitored at the tacked-on BNC jack […]

[Original post on mastodon.radio]
October 11, 2025 at 8:48 PM
Ran across an unfinished late-80’s project that would benefit from some time to poke around on: SHF Systems 144/902 MHz linear translator boards (3). Two boards are bare and a third has the oscillator built up that might be checked out with current test gear […]

[Original post on mastodon.radio]
October 11, 2025 at 6:04 PM
Further investigation of the EtherKit Si5351A shows it is a useful (square wave) signal source from 4 Hz up to 200 MHz when controlled by SATSAGEN. This is a versatile clock source that will add value here in the home lab. Monitored source output with the […]

[Original post on mastodon.radio]
October 10, 2025 at 8:33 PM