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Re: BITX40 package size
Jerry KE7ER I'm confused.? How does one get a negative output from a 3-terminal regulator with input shorted.? Where does the negative voltage come from? I see that we are almost neighbors.? I'm in Meridian Idaho.? May have to get together sometime for coffee and discussion of ham radio ideas. Arv K7HKL On Sun, Jun 11, 2017 at 11:55 AM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote: The 1n4148w is good for 300ma, plenty good for use in front of all LM78* on the Bitx40, including the Raduino. |
Re: BITX40 package size
The raduino is fine in as much as it powers up, displays frequency etc. I can't test the DDS output of it so it might not be completely fine but looking ok so far.
Raj: what voltage should I expect between base and emitter? I'm travelling for the next few days so probably want get to check until the end of the week - and there's no way I'm taking it on a plane with me, that's just asking for trouble! Matt 2E1HNK |
Re: Frequency from dds pcb
Just power the Raduino from a USB cable to keep all other circuitry quiet and attach a small wire to the DDS connector, you should be able to pick the signal on a nearby receiver on CW then zero beat it. Dan?That is if you don't have access to a frequency counter... On Sun, Jun 11, 2017 at 1:11 PM, EA3IAV <Cesarleon@...> wrote: is there a way to pick the actual freq from the dds in order to align it?? |
Re: New BITX-40 User and Antenna Recommendations
Thomas Noel
¿ªÔÆÌåÓýBoth will work, and both will have similar challenges as you can¡¯t fool Mother Nature.The (extremely) short loaded vertical will have low efficiency and narrow bandwidth, and will require a tuner. The magnetic loop will also have extremely narrow bandwidth and require adjustment with even slight frequency changes. Google K2MIJ and his extremely small antennas for HF, such as the 9¡± tall ¡°Limbo Stick¡± Another idea is the spiral loop. Thomas W Noel KF7RSF
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Re: Frequency from dds pcb
What works for me is to program it for the reference frequency and then use the result (read by a frequency counter) as the value to insert as your reference. For the Si5351 in the Raduino, for instance, use 25 MHz.
That eliminates the errors if you were to use a broadcast signal since it involves your BFO frequency, too. Don, ND6T |
Re: My Next Ham Radio Project
¿ªÔÆÌåÓýNice project.? Where do you source the Flux Capacitor from? Does Doc Brown sell kits for them? 73, Faisal VA3SFA On 06/11/2017 11:02 AM, Jerry Gaffke
via Groups.Io wrote:
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New BITX-40 User and Antenna Recommendations
Hi Everyone,
I ordered a BITX-40 a short while ago (A3-720). I've finally wired it together and got it working!! Once I have a decent small antenna I'll get on the air. I live in an apartment and won't be able to put up dipoles or large verticals. I am looking at two different options: 1 - A short (2m) vertical with a loading coil. 2 - A small magnetic loop. Have you tried the BITX-40 with any of these two types of antennae? What are your experiences and recommendations? Thanks and 73, VA3SFA/W6 |
Re: My Next Ham Radio Project
Suitable for framing! On Sun, Jun 11, 2017 at 10:33 am, K-Squared wrote:
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Re: BITX40 package size
The 1n4148w is good for 300ma, plenty good for use in front of all LM78* on the Bitx40, including the Raduino.
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The combination would be cheaper than my LM2940* But I still like the thought of an LM2940-12 up front to the main Bitx40 supply. ?Dropout at 150ma is around 0.13v, so 12.000 volts in would still give the Bitx40 11.870v. ?A diode plus LM78* would lose quite a bit more than that. I well remember how fantastic it was to have the LM309k to play with back in the early 70's. It did everything! ?And just 3 terminals! You could power a board full of 7400's and 7490's with it! ?> The problem of shorted regulators passing full voltage through them ... Correct me if I'm wrong, but I assume you mean the problem of a reversed supply. ? Jerry, KE7ER On Sun, Jun 11, 2017 at 10:28 am, Arv Evans wrote: 45 years ago in the LM340 regulator days it was conventional to always put a 1N400x in series ? |