A Crummy Commercial

 I saw this on the Digikey site: The PVI is no longer made ?  It's the heart of the Keyall HV and Keyall HV+.  I looked at the suggested replacement, it is surface mount but DigiKey doesn't sell it :(   This is a problem with the DigiKey notification system, if it's a part that hasn't been ordered recently, DigiKey doesn't send a notification.  I guess it's better than Mouser, they don't send anything at all.   Best Regards, Chuck, WB9KZY http://wb9kzy.com/ham.htm 

Seems like another nifty tech oriented website is gone ?: http://www.bunkerofdoom.com/  Luckily there are a number of hits on the wayback: https://web.archive.org/web/20240521124557/http://www.bunkerofdoom.com/  On a related note, I heard about this software: https://www.httrack.com/  A way to fully copy a site to a drive and then be able to look at it offline.  Might be useful for backing up the Jackson Harbor Press site or maybe even for this blog ?  One thing about a wayback archive is that there are often "holes" - pictures just aren't always preserved.  I remember a friend challenging the notion of backups once:  "do you fully verify the backup ?"  -  honestly, no.  I've been subscribing to the concept: " do lots of backups and hope that the aggregate will have everything " :) Also, something weird happened to a couple of backups I did manually to the wayback of the blog: I usually do them on Saturday of the previous 7 days of blog ...

I did a search using Duck Duck Go for:     pn5179 ham radio circuit schematic (I just happen to have a bunch of PN5179 transistors in the junkbox). And one of the links was: https://www.edaboard.com/threads/pn5179-equivalent-transistor-needed-for-construction.259327/  where I saw this: Ah, the little guy with the hammer !  That's from the QRP Popcorn blog.  So I tried looking at the QRP Popcorn blog and got this: Some of the QRP Popcorn pages are found almost completely intact on archive: https://web.archive.org/web/20241226034145/http://qrp-popcorn.blogspot.com/2022/10/some-analog-ic-gilbert-cell-mixer-notes.html  But I noticed that on some other pages, pictures and diagrams are missing, bummer ! BTW I also tried a search for: "Discrete BJT Transformerless Feedback Amp" (the title on that PN5179 circuit) and nothing - I was interested in seeing his comments on the circuit. Also, I didn't see any of his videos on Youtube either.  I'm hoping it's j...

I got another part discontinuation email from DigiKey today.  I've seen the BF256B notice three times now, first in January and then in June - I guess it's good they repeated them because I didn't remember the exact number. https://wb9kzy.blogspot.com/2025/01/these-are-never-good-news.html  https://wb9kzy.blogspot.com/2025/06/another-one-bites-dust.html  However this time they also included the MMBF5486 which is a surface mount JFET, so it's not just the TO-92 parts, in other words, it's not just leaded parts, also surface mounted parts. On a different note, I was looking at the 2SK-152 JFET mentioned here: https://wb9kzy.blogspot.com/2022/09/sony-2010-jfet-problems.html  I noticed an interesting grounded gate amplifier circuit on the data sheet.  Did a little more searching and found a datasheet with better resolution here: https://www.silicon-ark.co.uk/datasheets/2sk152-datasheet-english.pdf  Here is a screen shot: The datasheet is also available in this ...

Apparently the problem with the Muter was the IR decoder module.  Monitoring the output of the module there would be periods of noise pulses: Then the noise might shrink and the output would invert ! Sony TV mute code 29, output inverted from active low to active high, weird !   I'm guessing that this is some problem inside with the AGC ?   Here is a picture of the defective module: Anyway, found a Sharp decoder module in the parts box, unfortunately it isn't made anymore but it is a 40 kHz module which works with the Sony remotes. I hooked it up to the Muter in place of the defective module and now the Muter works ! However I will still abandon adding a timer to the Muter.  A mini-one button IR remote will be made for the Sony CMT-EP313 stereo with built in delay timing.  I found an example of a one button remote in the junkbox: from the now defunct All Electronics :( But with the 9V battery holder it would require some voltage regulation for use with a PI...

Say there was no internet, how would I know what the carrier frequency of a Sony infrared remote control was ? Measure it ! Here is the quick and dirty test fixture: An IR photodetector diode pulled out of a surplus scale circuit board.  Used the photovoltaic  "generation" capability of the photodiode and measured the voltage output with the scope.  Here is the zoomed out view: And zooming into 2.5 us per division: Counting divisions there are 10 in one cycle of the carrier, so 10 x 2.5 us is 25 us. IR Carrier frequency is 1 / 25 us => 40 kHz So we need a 40 kHz detector module for the Sony although a 38 kHz module like the one I had been using might work.  Next number: see if I have a 40 kHz module in the junk box or maybe pull it from some defunct Sony product ?  Or buy one (last resort). Best Regards, Chuck, WB9KZY http://wb9kzy.com/ham.htm 

Somewhere I saw an article by Bob Pease (or maybe by someone else at National Semiconductor?) in which he mentions that IC designers at National could go into the lab and find transistors similar to the ones used in National's bipolar process for analog ICs.  These TO-5 packaged "kit-parts" could then be used to prototype a new IC design on the bench.  Here is an example of one of those prototypes: I've never seen those kind of 8 pin round sockets before, they almost look like miniature tube sockets. picture source (LM168 voltage reference prototype): https://www.electronicdesign.com/technologies/analog/article/21808434/whats-all-this-pease-prototype-stuff-anyhow Unfortunately I am unable to find that article (although I did spend a pleasant afternoon looking on the internet at old Pease articles. The reason for this quest ?  It was this announcement made on the IEEE Spectrum page of the MOSbius Project: https://spectrum.ieee.org/mosbius-learning-analog-system-design...

Three items:  First, yet another end of life notice from DigiKey concerning JFETs, the MMBF5486: This JFET is a little more concerning since this is a surface mount device not the leaded TO-92 JFETs recently discontinued.  I guess the main thing is if the MMBF310 continues to be available in some form.  That's the surface mount equivalent of the J310 leaded device. The second item is an interesting article in the July/August issue of On The Air from the ARRL: I thought this was a clever idea:  change the numbering on a wall clock to show UTC time.  But as with a clock without numbers the normal local time can be read just by the position of the hands.  He also mentions replacing a regular quartz mechanism with an "atomic" clock mechanism.  I guess I didn't know that the movements (with hands) are available by themselves.  I saw this listing on Ebay: available but not that much cheaper than a whole clock Finally, the Brewers hit the LA Dodger all s...

I got my daily email from the Electronic Goldmine this morning, two items caught my eye: I realize these are "new" items rather than "sale" items but yikes, the prices ! On the Switch and Parts page: http://wb9kzy.com/switch.htm  I sell the C&K 7203 center off DPDT switch for 75 cents versus $11.95 ! I also sell the C&K 7201 DPDT switch in black for $2 new in bag: I sell the C&K 8121 momentary SPDT switch for $1 And I sell the C&K 8121 momentary SPDT switch for $2 new in bag with a black cap ! Maybe I should raise my prices ?  :) Best Regards, Chuck, WB9KZY http://wb9kzy.com/ham.htm 

Martin Clausen created a PIC programmer back when I first started using PIC microcontrollers around the turn of the 21st century: https://web.archive.org/web/20051226170059/http://www.rotgradpsi.de/mc/picprog/picproge.html The programmer hardware was driven by a PC parallel port, remember those ?  It was a command line DOS program that could be invoked in a batch file.  I used it with my late, lamented Sharp laptop.  It was a perfect way for me to develop PIC code.  Note that this was still the bad old days of EPROM PICs so I had my trusty Walling EPROM eraser right next to my keyboard.  Crash and Burn development ?  More like Erase, Burn and then crash ! But then the Sharp met an untimely death due to a bad hard drive.  I moved on to a Thinkpad and Windows.  The PIC programmer was a PICkit which could handle the newer parts like PIC12F683 which was used for the PK-4 keyer chip.  I depopulated the Clausen Picprog: and then in 2003, built a di...

 I saw this LSB: and this USB filter on Ebay: USB source: https://www.ebay.com/itm/326058586882 LSB source: https://www.ebay.com/itm/226549486681  I've mentioned the PRC-74 before: https://wb9kzy.blogspot.com/2022/09/just-dream-prc-74-transceiver.html  46 crystals, 4 rotating switches - it would be "easy" to replace those crystals with a Si5351.  The 4 rotary switches would also be easy to simulate using the same technique as the Morse Dial timer: https://wb9kzy.blogspot.com/2025/05/inspiration-for-kit.html  But the fly in the ointment may be seen in this: There is a LOT of ripple although the skirts are steep.  Hopefully the ripple is due to improper termination at the spectrum analyzer I/O ?  Also the price isn't super cheap for either filter.  And in these crazy times, how much tariff tax would be applied ?  Probably only one filter is needed since the Si5351 offers the builder an easily agile BFO. I suspect that the LSB filter is meant fo...

One of the motivations behind fooling with the Si5351 is that 7 MHz (and other crystals on even frequencies like 3.5 MHz, 14 MHz, 21 MHz, 28 MHz, you get the idea) crystals are hard to find.  I didn't see any in stock at Mouser.  The only one at DigiKey is marked obsolete, there are 107 pc. in stock: source:  https://www.digikey.com/en/products/detail/epson/MA-506-7-0000M-C3-ROHS/5260194  The price is right but they are surface mount crystals, so not compatible with the LF Converter kit: http://wb9kzy.com/lfconv.htm    HOWEVER, I was able to try one by soldering it to the bottom of the circuit board: (this is a pre-solder mask board, so the mod was easier, now the solder mask would have to be scraped or burned off) The two contacts on the beveled end (pins 1 & 4) are connected to the crystal and the other two are shorted together and are just used for support.  The 7 MHz is an MA-506 crystal: So I just lucked out on the mod, sometimes luck is bette...