Hi guys! Just wanted to show a pic of the radio with new knobs.
RL Drake MN2700 main tuning knob (2 inch skirt) on the encoder, with the kit-projects.com tuning knob on the volume...

Luxury tuning and volume!

73,
Kelly K5AID?

I appreciate the advice. I am going to definitely make use of shielding where possible. I'll make sure to bypass the rails and control lines as well as to make sure to keep leads as short as possible. I have scavenged quite a few parts from junk box boards. I will also be buying some toroids, trimmer caps, etc. shortly. At least I can start on the power switching section of the PA with what I have on hand.?

None yet. Was planning on using the ones recommended over ubitx.net unless I saw another idea appear I. The next month or so.?

73
AJ6CU

Derek, I had a problem wrth the s-meter sticking when I fist installed the agc board that seems to be resolved since I redid the wiring on the switch.

Did you use the latest instructions when hooking up the switch? The earlier version had a mistake in the wiring dagram.

73, digger AB3XU

I am glad that other ubitx enthusiasts are getting benefit from this project. Just a bit of payback for what I have learned. Thank you Farhan, Dr Lee and all other operators.

开云体育

I enjoyed the video... it was a good example of how physics COULD be taught... very instructive and helpful in showing how they came up with ways to test various hypotheses with relatively simple equipment.? (The video helped me to understand how they tested the idea of photons and their reasoning behind the test, something I'd wondered about in the past - and I'd had a year of physics.? I know how they showed the wave aspects of photons... learned that in high school.)

I would add that I've seen (and even owned, until someone torched my shop/lab) some really old test equipment, dating back into the 20s and 30s (plus a few electronics books and manuals from the same period and earlier - all ashes).? I know that the impedance bridge was old... dating to the mid 20s if not a bit earlier, and hams would 'roll their own' test equipment a lot back then.? They had some interesting ideas and equipment, back to the earliest days of radio.? Some of it would be a big problem today (rotary gap transmitter for instance), but it worked for them, and from what I remember reading back when I was a kid, they were well aware then of many of the problems inherent in the equipment being used and had novel ways of testing different aspects of radio.

My favorite piece that I lost in the fire (besides my books, radios, and modern equipment) was an optically amplified meter - that would measure a tiny fraction of a microamp.? They used a very sensitive meter movement, and used a light source to project it onto a wide screen.? It really worked well, and as I remember (the shop was torched in 2010), it dated well before 1920.? Beautiful finished wood cabinet, brass trim, and very well made (rather typical of the period).? (I also used to have a scope very much like the one in the video, but never really used it much - let it go years before.)

My in-laws, before they passed, had a big receiver that would receive from longwave clear up through shortwave - it dated (again, as I remember) to the 20s or 30s, well before WWII.? Again, gorgeous fancy wood cabinet (I think solid oak), brass and either nickle or silver trim, you name it.? Radios and test equipment were BUILT back then...

Bob

N4FBZ

Thanks to all the replies! After performing the mod to even up the bands, I suspect that I will need to turn the drive down. And I will keep the watt meter, it might be a tad high, but it is not way off either. I am wondering whether my dully load has a flat impedance response curve too. That could vary the output.

73
AJ6CU
Mark

And if you write using MacOS, it will definitely store "hidden files" on the flash and you will get the multiple file error message. Although there is supposed to be a way to see all hidden files on a Mac, it was far easier for me to slip it into a PC and find those files and delete them....

AJ6CU
Mark

Hi All

There needs to be a correction on the layout of the SD card.

Number 1

??? It *.TFT file doesn't need to be the only thing on the root of the card.

??? You can have a Folder there also.

???? I put all the Nextion display TFT files in the folder.

??? Then when we need a TFT file its all ready on the card,

?? Just copy the file needed? to the root.

?? P.S.? Don't forget to remove any files on the root that's not needed.

?? Just one TFT file on the root.


?? We put any update of the TFT file on the SD card when there updated.


? WB8LGA

? Charles

Hi,

It is interesting that the Bell Labs film and the MIT film both came out in 1959. In reading a little about the presenters in the films it looks like this was no accident. The Sputnik satellite launch sent shockwaves through the US and there was a big push for more and better science education.?

Both of these people (and certainly many more) obviously were very smart and interested in improving the physics education of the time. It is a good thing they were there to invent the teaching tools they did. Without the big science push of the day, maybe only the few that attended their lectures personally would have been lucky enough to see these demonstrations. It is fun (and educational) to see these time capsules from the beginnings of the space age.





A side note. Right after the Bell Labs wave video was another old video by Tektronix?on transmission lines. The interesting thing they did was send narrow pulses down a long coax cable and look at the pulses into the cable with open, short and proper termination. Had fun doing the same experiments this evening with a signal generator, scope and a long piece of cable TV coax. Also tried source termination, where the output of the coax is unterminated, but you terminate the input of the coax with a series resistor to the center conductor. I'd used the source termination method for sending digital data down ribbon cables in the past. Was fun to do this again just for play and remind myself it actually works.?

Thanks Laurence for linking the original video, it lead to a bit of fun and learning.

Tom, wb6b

Very similar results on my V4, a little less than yours on 20 (12w), a little more on 40 (9w), but the pattern is the same and a result of the filters selected on each band relative to the frequency. The rig will transmit anywhere, but should only be used between 80-10m as that is what the filter design is for.

=Vic=

I thank David for his design and for making the .stl file available.? I have just ordered four brackets from a local 3D printing service.? Beats buying a printer with attendant problems of assembling, setting up, adjusting, as well as finding space for it, and avoiding "discussions" with the beloved.
Vy 73,
Kevin,
VK3DAP / ZL2DAP

Thanks is all I need.?

The 80m LPF is also used for 60m, so the cut-toff freq is high enough to pass the third harmonic of 160m.
This is not a sine wave:
? ??/g/BITX20/message/48122

OK, if this is indeed the problem, found them at Arrow (my newest favorite supplier...). But which variant of MMMBT3904 is right? Looks like main difference is wattage (250-350mw). Get the highest wattage?

Mark

So V4 here. Audio was working (at least as well as it ever does on v4 if you want speaker output...), Was playing around with a higher impedance speaker (16 vs 8 ohm).still audio . Turned it off, solder speaker wire,, turned it on and no audio.... Bet I shorted the speaker wires somehow and blew the final stage.

Pulled out my Fluke 77, put it in diode mode, and Q72 appears to be a two way diode ;-) between Base and Collector. (i.e. Fluke reports .5 forward volts both ways) Checked the other 2n3904's, and none of them behaved this way.?

Am I interpreting this correct? There is only a 1k resistor between between base and collector... I am much more of a software guy.

If there is consensus here, any suggestions on sourcing the 2N3904??

73
Mark
AJ6CU

Yes, after much trial and tribulation I'm pretty happy, and confident, with my freq and bfo calibration.

-- digger AB3XU