Adrian Chadd
@erikarn.bsky.social
* he/him
* VR/AR prototype work at Facebook/Meta
* KK6VQK when RF
* Discord - therealerikarn
* FreeBSD, WiFi drivers/stack, Retro Computing, Random Electronics, and occasional kid/puppy stories
* https://erikarn.github.io/ for links to everything else
* VR/AR prototype work at Facebook/Meta
* KK6VQK when RF
* Discord - therealerikarn
* FreeBSD, WiFi drivers/stack, Retro Computing, Random Electronics, and occasional kid/puppy stories
* https://erikarn.github.io/ for links to everything else
good morning from my new mug
October 13, 2025 at 3:11 PM
good morning from my new mug
And I quote, $42.69 to Kat
please keep up the good fight!
please keep up the good fight!
September 19, 2025 at 9:48 PM
And I quote, $42.69 to Kat
please keep up the good fight!
please keep up the good fight!
July 30, 2025 at 6:03 AM
Yes, the coil form is very fucking melty.
July 29, 2025 at 11:54 PM
Yes, the coil form is very fucking melty.
It's 110 turns (around 8 layers?) of enamel coated wire around the form. The core is an iron transformer core.
July 29, 2025 at 11:54 PM
It's 110 turns (around 8 layers?) of enamel coated wire around the form. The core is an iron transformer core.
So I ordered a replacement 144MHz RF board for the TS-790 so I can replace and document/reverse engineer some damaged coil packs on one I repaired recently.
Anyway. This RF board is a bit special.
I give you ... one good and one cooked coil.
Anyway. This RF board is a bit special.
I give you ... one good and one cooked coil.
July 29, 2025 at 11:54 PM
So I ordered a replacement 144MHz RF board for the TS-790 so I can replace and document/reverse engineer some damaged coil packs on one I repaired recently.
Anyway. This RF board is a bit special.
I give you ... one good and one cooked coil.
Anyway. This RF board is a bit special.
I give you ... one good and one cooked coil.
sorting out paperwork and found this
July 26, 2025 at 11:17 PM
sorting out paperwork and found this
me: "hm the bandpass filter, used for both the TX and RX paths, is still pretty shit."
also me: "oh, hm, it's like 10+dB down"
also me: "wait it's 10dB down between the RX connector and the switches BEFORE the BPF"
also me: "oh for fucks sake diode, why are you now a resistor sigh"
also me: "oh, hm, it's like 10+dB down"
also me: "wait it's 10dB down between the RX connector and the switches BEFORE the BPF"
also me: "oh for fucks sake diode, why are you now a resistor sigh"
July 25, 2025 at 3:51 AM
me: "hm the bandpass filter, used for both the TX and RX paths, is still pretty shit."
also me: "oh, hm, it's like 10+dB down"
also me: "wait it's 10dB down between the RX connector and the switches BEFORE the BPF"
also me: "oh for fucks sake diode, why are you now a resistor sigh"
also me: "oh, hm, it's like 10+dB down"
also me: "wait it's 10dB down between the RX connector and the switches BEFORE the BPF"
also me: "oh for fucks sake diode, why are you now a resistor sigh"
Heh.
My most recent build came out OK, but it's a frankenbuild in a 2ru case - aldar lake, "commercial" motherboard with pcie and PCI slots for testing older hardware, a bunch of SATA SSDs and RAM. It mostly all fit.
It /did/ take some searching to find RAM that didn't hit the heatsink though!
My most recent build came out OK, but it's a frankenbuild in a 2ru case - aldar lake, "commercial" motherboard with pcie and PCI slots for testing older hardware, a bunch of SATA SSDs and RAM. It mostly all fit.
It /did/ take some searching to find RAM that didn't hit the heatsink though!
July 22, 2025 at 3:53 PM
Heh.
My most recent build came out OK, but it's a frankenbuild in a 2ru case - aldar lake, "commercial" motherboard with pcie and PCI slots for testing older hardware, a bunch of SATA SSDs and RAM. It mostly all fit.
It /did/ take some searching to find RAM that didn't hit the heatsink though!
My most recent build came out OK, but it's a frankenbuild in a 2ru case - aldar lake, "commercial" motherboard with pcie and PCI slots for testing older hardware, a bunch of SATA SSDs and RAM. It mostly all fit.
It /did/ take some searching to find RAM that didn't hit the heatsink though!
Well, i finally got one of the transmit bandpass filters tuned correctly. This is the bandpass filter on the IF board, before the signal is sent to the RF power amp.
If they're tuned to the right bandwidth but they're not tuned for the right /level/ then the final drive stage doesn't get enough RF.
If they're tuned to the right bandwidth but they're not tuned for the right /level/ then the final drive stage doesn't get enough RF.
July 19, 2025 at 5:32 PM
Well, i finally got one of the transmit bandpass filters tuned correctly. This is the bandpass filter on the IF board, before the signal is sent to the RF power amp.
If they're tuned to the right bandwidth but they're not tuned for the right /level/ then the final drive stage doesn't get enough RF.
If they're tuned to the right bandwidth but they're not tuned for the right /level/ then the final drive stage doesn't get enough RF.
here it is in it's mostly fine glory. The fan doesn't switch on right though - it's still got some stuckiness due to age, so I may need to pull it completely apart and attempt to clean and re-lubricate it.
Or shit, I wonder if the drive transistor isn't able to drive it to ground strong enough. Hm.
Or shit, I wonder if the drive transistor isn't able to drive it to ground strong enough. Hm.
July 8, 2025 at 5:52 AM
here it is in it's mostly fine glory. The fan doesn't switch on right though - it's still got some stuckiness due to age, so I may need to pull it completely apart and attempt to clean and re-lubricate it.
Or shit, I wonder if the drive transistor isn't able to drive it to ground strong enough. Hm.
Or shit, I wonder if the drive transistor isn't able to drive it to ground strong enough. Hm.
oh look now i know why the thermal control loop in this radio isn't working.
what the fuck has this radio SEEN?
what the fuck has this radio SEEN?
July 7, 2025 at 12:01 AM
oh look now i know why the thermal control loop in this radio isn't working.
what the fuck has this radio SEEN?
what the fuck has this radio SEEN?
ok, so
the yellow caps are 47uF replacements from the "these are cheap caps only use them for hacking not repair", and with these the rails going into the amplifiers suck less, and
.. well, the three bipolar caps have been temporarily replaced with MLCCs.
And all is good.
the yellow caps are 47uF replacements from the "these are cheap caps only use them for hacking not repair", and with these the rails going into the amplifiers suck less, and
.. well, the three bipolar caps have been temporarily replaced with MLCCs.
And all is good.
July 5, 2025 at 11:52 PM
ok, so
the yellow caps are 47uF replacements from the "these are cheap caps only use them for hacking not repair", and with these the rails going into the amplifiers suck less, and
.. well, the three bipolar caps have been temporarily replaced with MLCCs.
And all is good.
the yellow caps are 47uF replacements from the "these are cheap caps only use them for hacking not repair", and with these the rails going into the amplifiers suck less, and
.. well, the three bipolar caps have been temporarily replaced with MLCCs.
And all is good.
i figured out why the finals didn't work
So, that works, now I just need to finish figuring out the low FM MIC audio level. Time to make or find a suitable audio generator.
So, that works, now I just need to finish figuring out the low FM MIC audio level. Time to make or find a suitable audio generator.
July 5, 2025 at 9:09 PM
i figured out why the finals didn't work
So, that works, now I just need to finish figuring out the low FM MIC audio level. Time to make or find a suitable audio generator.
So, that works, now I just need to finish figuring out the low FM MIC audio level. Time to make or find a suitable audio generator.
I found oxidised copper /inside the bloody LCD panel cables/. I tore the LCD completely down and .. jesus.
Anyway, all of that ended up blowing a 500mA surface mount fuse on the LCD board. No other damage was visible.
So, I give you (with a temp wire instead of the fuse) ... it fucking BOOTING.
Anyway, all of that ended up blowing a 500mA surface mount fuse on the LCD board. No other damage was visible.
So, I give you (with a temp wire instead of the fuse) ... it fucking BOOTING.
July 4, 2025 at 3:55 AM
I found oxidised copper /inside the bloody LCD panel cables/. I tore the LCD completely down and .. jesus.
Anyway, all of that ended up blowing a 500mA surface mount fuse on the LCD board. No other damage was visible.
So, I give you (with a temp wire instead of the fuse) ... it fucking BOOTING.
Anyway, all of that ended up blowing a 500mA surface mount fuse on the LCD board. No other damage was visible.
So, I give you (with a temp wire instead of the fuse) ... it fucking BOOTING.
Then I cracked out the powerbook 540c which never quite worked well.
It was NOT immaculate. It had leaky battery gunk everywhere, so much blue copper gunk everywhere. The LCD was just all white.
Here's the corner of the case and screen - you can see the blue copper stains that are left.
It was NOT immaculate. It had leaky battery gunk everywhere, so much blue copper gunk everywhere. The LCD was just all white.
Here's the corner of the case and screen - you can see the blue copper stains that are left.
July 4, 2025 at 3:55 AM
Then I cracked out the powerbook 540c which never quite worked well.
It was NOT immaculate. It had leaky battery gunk everywhere, so much blue copper gunk everywhere. The LCD was just all white.
Here's the corner of the case and screen - you can see the blue copper stains that are left.
It was NOT immaculate. It had leaky battery gunk everywhere, so much blue copper gunk everywhere. The LCD was just all white.
Here's the corner of the case and screen - you can see the blue copper stains that are left.
In "oh cool the kids aren't here so I can work on projects and clear my head" news
I cracked the powerbook 170 out of storage and cracked it open to clean it up.
it required no cleaning. One bluescsi v1 and 7.6.1 later and bam. Now I just need a serial cable and i'll get it on appletalk.
I cracked the powerbook 170 out of storage and cracked it open to clean it up.
it required no cleaning. One bluescsi v1 and 7.6.1 later and bam. Now I just need a serial cable and i'll get it on appletalk.
July 4, 2025 at 3:48 AM
In "oh cool the kids aren't here so I can work on projects and clear my head" news
I cracked the powerbook 170 out of storage and cracked it open to clean it up.
it required no cleaning. One bluescsi v1 and 7.6.1 later and bam. Now I just need a serial cable and i'll get it on appletalk.
I cracked the powerbook 170 out of storage and cracked it open to clean it up.
it required no cleaning. One bluescsi v1 and 7.6.1 later and bam. Now I just need a serial cable and i'll get it on appletalk.
oh look the free parts radio someone gave me lives
June 29, 2025 at 10:00 PM
oh look the free parts radio someone gave me lives
