February 10, 2023
SolderSmoke Podcast #224 is available.
http://soldersmoke.com/soldersmoke243.mp3
Video here: (32) SolderSmoke Podcast 243 (video) Hi7/N2CQR, uBITX, Success with High School Receiver Project - YouTube
Pete N6QW had technical difficulties this morning. He insisted that the show must go on. Pete will be back for the next episode.
Travelogue:
Bill in the Dominican Republic for all of January.
HI7/N2CQR Eastern
tip of the island. uBITX and dipoles.
20, 17, 10. CW and
SSB. SSB was tough and I had reports of
RF getting into the signal.
Went to CW.
Worked VWS Mike KA4CDN, and Walter KA4KXX on 20CW.
Finally moved up to 10 CW. Lots of contacts. Even though uBITX very QRP
on ten.
I am modifying the uBITX now.
Copper tape shielding to keep RF out.
Low power out not
the fault of the IRF-510s. The problem
is the 2N3904s.
Will replace with 2N2222 in To-18 cans.
Dean KK4DAS putting KD8CEC software into Arduino. I gave up.
Who sent me this orphan uBITX?
SolderSmoke Shack South in final phase of construction.
SHAMELESS COMMERCE DIVISION:
Patreon!
Bezos Shopping!
DC Receiver Project
Local High School radio club.
Simple: Like
Herring Aid 5 and Wes’s original.
Farhan’s four
stages:
BP Filter, Diode Ring, PTO, AF amp.
Simple Colpitts PTO SURPRISINGLY STABLE.
Simple and easy.
No chips. No complicated circuits.
Guys have helped test out the design: Rick N3FJZ, Walter KA4KXX,
Daniel VE5DLD, Stephen
VK2BLQ and others.
First session last night: We demonstrated build of the PTOs.
They worked (thank God).
Open Circuits book.
Envelope Detection Controversy
Save the Antenna – Book “Losing the Nobel Prize” K1JT
MAILBAG
--Dean KK4DAS 10 meter DSB!
Tiny SA ULTRA! FB
--John AC2RL on Elmer W3PHL DSB guy
--AC3K reports inventor of Fender Stratocaster guitar was a
ham: W6DOE
--AF8E was doing POTA.
I worked him. He said my rig had presence. FB
--Alain F4IET FB DSB rig with mic in Cigar can!
--Daryl N0DP worked him on SSB. He is homebrewing
--Steve N8NM was in for repairs but is on the mend.
--Rick G6AKG working with sub-harmonic mixers and logic chips
--Paul HS0ZLQ Built DC receiver but looking for something
else to build. No DSB!
--Steve AB4I – Coherer, Jagadish Chandra Bose, and Marconi
--Eldon KC5U
Worked VK5QD right after me and mentioned SolderSmoke FB
--Todd K7TFC is building the DC RX.
--Tony G4WIF and Ian G3ROO using automotive relays for
antenna switching. FB.
--Dave WA1LBP Great to hear from my fellow Hambassador (Okinawa)
Older post comments:
--Scott VO1DR was also in CF Rockey’s class! (Blog comment)
--Aurora Aug 4, 1972: Twelve people shared memories. (Blog comment)
--Will WN1SLG Googled novice call and was led to
my Novice log.(Blog comment)
Posts
Bill, LICW training covers the /, and the procedural K, you are spot on with your observations..Ed KC8SBV
ReplyDeleteExcellent podcast, even without Pete. Congratulations on the high school DC project debut. I'm about 2/3 through my own build.
ReplyDeleteHi Bill. Thanks for the mention. I'm building your direct conversion reciever but I'm changing the frequency to 21 mhz.
ReplyDeleteIm going to try the PTO ocsollater. I've never made one before and it looks interesting to me.
I will let you know how I get on.
73's.
Paul. De HS0ZLQ /G0MIH.
Thanks Paul. But I think you may have trouble stabilizing the oscillator at 21 MHz. We were surprised that it was stable at 7 MHz. 21 MHz is, I think, pushing the envelope. But good luck. 73 Bill
DeletePaul HS0ZLQ would have a good chance of success with a 15M version by building the PTO for 10.5 MHz and then using the two transistor frequency doubler circuit in the 15M transmitter design by WA1LNQ which is Figure 36 on page 50 of Solid State Design.
DeleteThis comment has been removed by a blog administrator.
ReplyDeleteHi Bill, is there one place, with a link to it, where I can find the complete schematic (sorry Pete!!!!) for the final version of the high school direct conversion receiver? Or maybe two or three links to the final versions of the parts of it? Thank & 73
ReplyDeleteJerry aa1of
Where could I find the final version of the hi school dc receiver? Tnx Jerry aa1of
ReplyDeleteHere you go Jerry: https://soldersmoke.blogspot.com/2023/01/a-call-for-builders-please-help-us-test.html
DeleteLots of other info on this project on the blog at https://soldersmoke.blogspot.com/search/label/TJ%20DC%20RX
Bill, after listening to podcast 243 and your uBITX low output on 10 meters I needed to dig out my notes on mine. If you look at the RF drive level at the junction of C82 and RV1 you will notice a large difference about half as much drive on 10 as you’ll see on 160 or 80 meters. The gain on this stage needs to be flattened across the whole range, or at least increased at the upper frequency end.
ReplyDeleteI did the changes that Howard WB2VXW suggested (on the uBITX group) which was adding a 33uh inductor in series with R81 and a 220pf cap across R82. I also replaced Q90 with a 2N2222A. Similar additions were added to the other driver stages the result was a doubling of the drive at C82/RV1 junction and I now see 3 watts out on 10 meters instead of the 1.25 watts I originally measured. I adjusted RV1 on 40 meters for max output until no increase is noticed and then back is off a touch.
I measured an increase power-out across the bands and bands above 30 meters there was a doubling of output. I hope this might be of help.
Another question for you when I use the link to Amazon on you page and buy stuff I have on my wishlist do you still get credit? I still put something in the search window to find but end up buying also from my wishlist.
Forgot to add my name and call to uBITX response.
ReplyDeleteSkip NC9O
Thanks Skip. I did most of the mods suggested by Allison KB1GMX. I replaced the 2N3904s in the driver with 2N2222A. I also changed the emitter resistors to 11 ohms and changed the cap she recommended. I too saw power out on 10 go from 1 watt to 4 watts. I am now thinking of changing the pre-driver resistor. It is surface mount, and tiny, but Todd K7TFA of Mostly DIY RF has them on small PC boards, so I will also try this mod.
DeleteAs for your wish list, I think I get credit only for the things that you search for through my blog. So you might want to search again (on the SolderSmoke blog site) for the wish list items. 73 Bill