Dan Maloney
I do reuse some stages, but more often than not I simply reuse the componts.
Also, build the fittings jto support the pots, caps and switches using a 3d printer
I don't tend to box up my rigs as I like to see the electronics.
@James Finch - Aren't you tuck with FSK and OOK with the Si4432? IOW, no AM, SSB, or FM?
*stuck
Anyone played with the Teensy?
Great little uPs. Very powerful.
Everytime I start with a box on a build I end up in a corner with lack of space or trying to trouble shoot down in a hole
@Charlie Morris ZL2CTM - I have one in a half-built virtual subtractive synth on a shelf :)
started to when you were playing with SDR
@Charlie Morris ZL2CTM I've been using teensys for a few years, great devices! haven't had a chance to play with the 4 yet but I have one at home
Nice. They did a great job with that. The audio lib is really good too.
@MS-BOSS I've been trying to be patient and wait and see what everyone else has done first. tinySA (HBTE groups.io), UHF Spectrum Analyzer (instructables) and the Hackaday.io https://hackaday.io/project/2443-handheld-3ghz-spectrum-analyzer
have you ever tried building software selectable filters, charlie? either with fets or relays
The other hard part being here in NZ is getting components. I often have to ship them in from overseas, Especially toroids.
I suspect that we're all about to face that Charlie
Yes. I did use some relays a while back to sw in and out caps for a BPF. It worked. I want to do it again for a 80/40m rug.
I kept the inductance the same and varied the cap. The passband characteristics were a bit wonky, but it worked.
Usually, a better approach than relays are PIN diode switches. At least these days.
Are there special considerations in sending RF through relay contacts?
@Charlie Morris ZL2CTM Do you have a known god aliexpress supplier of toroids?
@Dan Maloney Still researching and compiling resource data. Have to review the code to understnd.
@Dan Maloney You don't want to send more than a few watts through relay at the moment it is trying to disconnect the contacts. Then you get a lot of magic smoke.
For low level RF i have not had any problems with small relays. For high power yes. I tend to use either salvaged HF radio ant relays, or high current AC/DC relays. I havn't burned any contacts out with that approach.
@Dan Maloney For long operating life, cut the output power before switching the relay.
Magic smoke. The key to everyhting.
I get my toriods form Kits and Parts
@Dan Maloney Hermetically sealed relays with vaccuum inside are the best, however I have not seen them in years. At least not with sane price.
@James Finch -Seemed to me when I read Silicon Labs data sheets on those chips is that they're geared mostly for transmitting and receiving data. They do make a line of FM broadcast receivers that output analog audio, but they're limited to the broadcast band 88.1-108MHz here in the States)
As for AliExpress. I don't have any one specific supplier. I have been burned buying IRF510s. I only buy those through a local supplier.
@MS-BOSS - Thanks for the tips!
I got a SPDT RF relay with SMA connectors from a ham fest earlier this year. Going to use it for a TX/RX relay with my LimeSDR Mini. Depending on its power level.
Are the transitor and diode switches worse at HF? Guessing the RF switch IC's are a lower power option.
See the photo above for the relays. All the blacl ones are 1A 30VDC
I'm starting to use more and more SMA connectors. Not sure what the max power rating is for them.
GAN fets may be useful RF switches now. They are very cheap for very high currents and voltages, but have lots of gate leakage current. I have just started looking into them. Spiteful bumped die packages but.
@James Finch Even cheap PE4259 can handle +33.5 dBm into 50 Ohm load. Depends on your view of lower power.
I'm mostly QRP, so 5W or so out of the PA.
I hope I am answering your quesitons.
@Dan Moloney Si443x (Si4431 is a little weaker TX signal): https://www.silabs.com/documents/public/data-sheets/Si4430-31-32.pdf
We're getting up to the end of the hours, and although Charlie has the day off, we can't keep him away from the bench all day. I just want to say thanks to Charlie for getting up with the sun and spending his morning with us. I found this super useful, and I can't wait to try out some homebrew stuff myself.
Thanks Charlie! 73 de N7DPM, and thanks to everyone how made this a great chat today!
Thanks!
many thanks Charlie - very much appreciated
Thank you!
Thanks for the chat.
Thanks, Charlie.
My pleasure.
Don't forget that next week we'll be talking with Samy Kamkar about side-channel attacks and reverse engineering:
@Charlie Morris ZL2CTM power rating depends on the brand and type...here's an example https://mpd.southwestmicrowave.com/wp-content/uploads/2019/01/power-rating.pdf
https://hackaday.io/event/170293-side-channel-attacks-hack-chat
Side-Channel Attacks Hack Chat
Samy Kamkar Wednesday, March 25, 2020 12:00 pm PDT Local time zone: Hack Chat This event was created on 03/09/2020 and last updated a day ago. Join this event's team Samy Kamkar will host the Hack Chat on Wednesday, March 25, 2020 at noon Pacific Time. Time zones got you down?
Thanks Trevor.
Feel free to stay on and chat, of course. The Hack Chat never closes!
I'm here.
ah cool, you should make sure it's posted on the frontpage again next tuesday so i don't forgot
thanks charlie, i do enjoy your videos
Charlie, really appreciate those videos where you explain how you get to the values that you do !1
Thanks. I hope they are useful.
For sure! Enabled envisioning in more detail what those block diagrams are doing. Same with the IC's that perform those roles. Thanks Charlie!
I know the circuits are super simple, but that's what I am trying to do. I want others to see that it's not hard.
Yep, we run a post for the upcoming Hack Chat on Monday (usually) or Tuesday, and flog it in the newsletter that goes out Wednesday. I can also add you to the email reminder that goes out 30 minutes before the chat if you DM me your email address.
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