Re: Frequency from dds pcb
Ok Cesar, I don't think you'd fry your counter, the freq amplitude directly from the Raduino is pretty low, if unsure just make voltage divider with a potentiometer and feed the counter through a small capacitor (about .01uF).
That's ok, you're reading the VFO frequency which is about 5MHz, since the IF freq is 12MHz (12-5 = 7 MHz).
On Sun, Jun 11, 2017 at 1:43 PM, EA3IAV <Cesarleon@...> wrote: I have a freq counter but I don't want to fry it. I mean, where do I tiuchbwith the wire in order to pick freq without overloading the fcounter
thanks
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Re: My Next Ham Radio Project
O'Reilly Auto Parts has them listed but do not seem to be for sale at this time
DuWayne KV4QB
--
DuWayne? KV4QB
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Re: Frequency from dds pcb
If you are worried about not having a blocking cap on the frequency counter then unplug the connector that you have attached to "DDS1" and measure right off of that. There is a blocking capacitor on the Raduino. If you program the reference frequency (25 MHz, not 7 MHZ (7 MHz is NOT your reference crystal frequency!) then you will get a value around (but seldom right on) 25 MHz. That is your "reference" frequency, the frequency of your reference oscillator on the Raduino.
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That's good news!
If it displays ok, the output from the Si5351 PLL chip is likely ok too.
I can't imagine why D7 blew unless it saw reversed power supply leads.
Could be that you have a power supply not capable of putting out enough current
to blow the LM7805 regulator on the Raduino.
How many amps is your 12v power supply capable of putting out?
Jerry
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On Sun, Jun 11, 2017 at 11:37 am, <mattcarus@...> wrote:
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.
?
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Re: Frequency from dds pcb
What frequency should I get if I attach a freq counter to te dds connector? At 7.000mhz on the dds I read 5.005,687 on the fcounter
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Re: Frequency from dds pcb
I have a freq counter but I don't want to fry it. I mean, where do I tiuchbwith the wire in order to pick freq without overloading the fcounter
thanks
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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.
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
with the regulator input. ??? The problem of shorted regulators passing full voltage through them was?well known and accounted for with the series diode.
?
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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
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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.
?That is if you don't have access to a frequency counter...
Dan
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??
Thank you
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Re: New BITX-40 User and Antenna Recommendations
Both 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.
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On Jun 11, 2017, at 11:15 AM, Syed Faisal Akber < faisal@...> wrote:
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
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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
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Re: My Next Ham Radio Project
Nice 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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Suitable for framing!
As are many of Randall's offerings.
Here's the manual: ???
Jerry, KE7ER
On Sun, Jun 11, 2017 at 10:33 am, K-Squared wrote:
Here's a schematic.? I'll try to include a
complete parts list later.
?
?
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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
|
is there a way to pick the actual freq from the dds in order to align it??
Thank you
|
Re: My Next Ham Radio Project
Suitable for framing!
As are many of Randall's offerings.
Here's the manual: ???
Jerry, KE7ER
On Sun, Jun 11, 2017 at 10:33 am, K-Squared wrote:
Here's a schematic.? I'll try to include a complete parts list later.
?
?
|
The 1n4148w is good for 300ma, plenty good for use in front of all LM78* on the Bitx40, including the Raduino.
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
toggle quoted message
Show quoted text
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
with the regulator input. ??? The problem of shorted regulators passing full voltage through them was?well known and accounted for with the series diode.
?
|
My Next Ham Radio Project
Here's a schematic.? I'll try to include a complete parts list later.
|
DuWayne Schmidlkofer
Don, ND6T
Matt Carus