My BitX20 Choice.

Started by gil, May 24, 2015, 10:29:51 PM

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gil

You're right Bob, I plan on doing just that :-)

The BitX20A is to take sailing, and hopefully I'll get to go in a couple months!

Gil.

gil

#16
Well, I finished the BitX20. It doesn't work :(

I've built so many kits, including a K2, and they all worked immediately... This kit was no walk in the park. First, the manual is riddled with errors. To anyone wanting to build one, DO NOT follow the manual to the letter. Some resistors are labeled with the wrong colors, especially the 10 Ohm, 100 Ohm and 1 kOhm variety... Follow the component values, not the colors. Download the BitX17A manual, it is much better.

Then I inverted the two molded inductors, broke one while unsoldering it >:( I ordered a replacement, but now I have to wait. The VFO works mind you, I get about a 150kHz tuning range, though I might replace the polyvaricon with a varactor later for more range. The BFO seems to work too, I measured the 11mHz signal with a cheap frequency counter. I did hear some signals and voices but very faint. There is definitely a gain problem somewhere. The transmitter section does not seem to output anything, another mystery to solve. I hate troubleshooting.

Well, if I had a scope and an HF signal generator, it would be much simpler... Anyone has an old 20mHz oscilloscope pickup up dust in his basement?

It will be a week before I get back to it. I hate having $200 sitting like that...

Gil.

RadioRay

#17
"space ninjas..."

Well, just remember that > I < am the one to whommmmm the aliens gave a silver rubber jump suit! I'd rather not explain what I had to do to earn it though ...

-...-

From experience and for my use, the go-to in wilderness or foreign remote assignments has been Morse because of very low power requirement for the same intelligence transfer which translated in tiny power consumption. The ability to easily and quickly send a written text/cipher text message with minimal support/consumption was important. 35 mA on receive for an MTR RIG  and a 13 to 18 dB SYSTEM GAIN FOR CW compared to voice is why I use Morse 99% of the time, especially in the field where I carried my gear in addition to my normal load-out and had to recharge batteries in my "spare time"  ;-/

In a grid-up or easy recharge environment , I might use digital like the winlink system, using RMSexpress on the tablet. However, it and especially
Voice requires a much better signal to noise radio than Morse for the same exchange. For me personally , I have little use for voice outside of quick reaction tactical comms and it's very tough to support in the field due to the required power levels .

It's FUN however to chat with people in voice if that is what you're into and a necessity when dierating a group quickly, usually in close area operations. We ALL agree "Radio is magic!



"When we cannot do the good we would, we must be ready to do the good we can."  ~ Matthew Henry

gil

Hello Ray,

Well, voice is not what I'm into but I want to be able to listen to and participate in the 14300 maritime nets while on the boat.. So, now I have to troubleshoot this thing :( The only kit I built that didn't work right away uses USB! Go figure :o The Morse gods know I did something wrong and are punishing me!

Gil.

RadioRay

Oh yes - MMSN is great for sailors and life aboard is supported by HF Radio. How well I remember.

Ray
"When we cannot do the good we would, we must be ready to do the good we can."  ~ Matthew Henry

beewhisperer

I am not a prepper, though I can show you how to pickle anything in about 5 days without vinegar or cooking, and I can take you out in a field and show which grass seeds to pick, grind them up and make pancakes.  Just old world methods.  I regret i did not learn CW long ago.  One thing most forget about CW.  Its not just Morse code.  Letter swapping is easy light security, however you can make you own code for a neighborhood watch, where a combo of just 4 dots and !dashes can mean 16 different sentences. (binary 4 bit)  eight would give you 256.  Think of it.  #14 (i am at wiggens)  # 46 (i have food) #67 (I need water) # 108 (I am ok for now).  NVIS is also harder to trace than say uhf or vhf.  I am going CW all the way.

K7JLJ

You can do the same with phone using mike breaks and have the ability to talk in a hurry if needed..

Two breaks means approaching from East.  Then all hell breaks loose... "They broke through the roadblock and have grenades, 100M from base!"

Try tapping not that out under stress ;)


- Jim
-Jim

gil

Hello,

A code like this is fine as long as it is short. Remember, Morse code is only 26 letters... So, if your code is longer than maybe 15 items, you might as well learn Morse. It is very easy to learn it at about 7wpm, anyone can do it rather quickly. I would never suggest anyone to learn it that slow, but it's better than nothing.

Update on the BitX20: Still no cigar :(

The receiver works, though the audio volume seems very low.

I followed the calibration instructions for the transmiter and went as far as biasing the output transistors. Problem is, I get zero drive from the microphone. I replaced one transformer and one transistor, to no avail. All components in that circuit are correct. Darn!

Gil.

cockpitbob

Good luck with that Gil.  Especially without an o-scope, debugging radio electronics can be really tough.

gil

I have about a dozen scopes in my Ebay watch list right now, all below $100.. Big analog boat anchors, but hey, it it works, who cares...

Gil.

KK0G

I've had pretty good luck tracking down problems like that with no oscilloscope. The little RF detector trick that's shown in the Elecraft K2 manual seems to work pretty well using the schematic and process of elimination.


Sent from my iPhone using Tapatalk
"Those who would give up essential liberty to purchase temporary safety, deserve neither liberty nor safety" - Benjamin Franklin

KK0G

gil

QuoteThe little RF detector trick that's shown in the Elecraft K2 manual seems to work pretty well using the schematic and process of elimination.

Yep, I've got one of those. It's so nice to see what the waveform looks like though...

Gil.

KK0G

#27
Quote from: gil on June 20, 2015, 07:14:31 PM
QuoteThe little RF detector trick that's shown in the Elecraft K2 manual seems to work pretty well using the schematic and process of elimination.

Yep, I've got one of those. It's so nice to see what the waveform looks like though...

Gil.
Yeah, but in your case you have no signal so you don't even have a waveform to look at, hence my comment about the detector. If I was a betting man I'd wager it's something dirt simple like a missed or cold solder joint, diode in backwards, etc. When I built my K2 I had no receive on one band, 40 meters if I recall correctly, I used the schematic and detector to eliminate entire receiver sections at a time and narrow it down to a very small part of a single section. It probably took me less than 20 minutes to find the diode where the signal stopped, and another 30 seconds with a magnifying glass to reveal the solder joint I missed on one side of that diode. One missed joint out of the thousands of solder joints I made in that K2? I didn't think that was too bad. ;D
If you have no mic signal you could use the same trouble shooting technique to locate the problem.
"Those who would give up essential liberty to purchase temporary safety, deserve neither liberty nor safety" - Benjamin Franklin

KK0G

gil

Yep, I just need to go through it again. I have a small guitar amp I can use to follow the path from the microphone to wherever the problem is... Once I can't hear myself anymore I'll know where it is..! On the positive side, following schematics is good schooling..

Gil.

KK0G

Quote from: gil on June 20, 2015, 10:51:34 PM
...... On the positive side, following schematics is good schooling..

Gil.
I totally agree with that. Following the instructions to build a kit doesn't really teach you much about electronics, it teaches you to mainly how to follow instructions, identify components, populate boards with those components, and solder. I've learned far more by trouble shooting my screw ups than successfully completing a kit that works perfectly the first time it's fired up. I have no doubt you'll find the problem, good luck.
"Those who would give up essential liberty to purchase temporary safety, deserve neither liberty nor safety" - Benjamin Franklin

KK0G