the Bitx40 uses 12v natively however the qrp-labs DDs vfo requires 5 volts. I have tried several buck converters but there is a lot of hashing (noisy) when the converter is powered on. Anyone have a suggestion as to anything I might try. If I use an external 5 volt wall wart then the problem (noise)?goes away. I don't want to have a 12 v power connection and have to run a wall wart also. 73 art
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Re: (Raduino) A Duhhh.... Moment
Ok, I see where to cap goes, totally missed that at first. ?Just wondering on the 50 turn torroid now.
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Re: (Raduino) A Duhhh.... Moment
So I remove L4, and what do I do with the 50 turn toroid? ?Also, anyone know what the .01 uf cap is for that it came with?
Thanks, Janson W7TJS
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Re: Low Power - Final Amplifier on through - hole kit
Greetings all.
I started tracing my PA with Leonard's documentation.?
The first discrepancy I noticed right away.?
He had 30v pk-pk on the collector of Q1 (2n2218) and I only had 15.94v pk-pk. And the waveform is quite different. My guess is that the problem is around here. I double-checked all the component values, orientation of the 2n2218, and my solder joints. I'm still stumped.
Attached is a capture from the scope.?
My voltages at Q1 were as follows:?
Base: 1.79v Collector: 10.97v Emitter: 1.14v
And yes, I am running the entire board from a 20vDC regulated bench power supply (HP3630A), and I am feeding in 2v pk-pk at 14.00MHz from the function generator (Tektronix AFG3251).
Any insights would be much appreciated!
On Sat, Jan 21, 2017 at 6:09 PM, Jorge Luiz Fenerich <py2pvt@...> wrote: ? ? Thanks Leonard for finding this page I was needing it and I need to know also the voltages in Q1 (2N3866) if you know please pass me ok?? ? Jorge PY2PVT _._
-- Mark Baldridge 608.561.3853
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Re: Different display issues
Hi Jack, I have been battling "noise clicks" for some time now in my DDS. I have tracked it to the i2c bus SDA data being injected in the power rail by my OLED display, the bitx is so sensitive it acts on this noise, my Mst3 with the exact same DDS doesn't have this problem.?
Anyway, the only way I could reduce this noise after many tests and redesigns was to put a D.C.-D.C. Isolator in the power rail for my OLED display. it didn't remove it 100%, more like around 95% - but at least it was usable.? A simple voltage regulator (7805) and associated filter caps and even chokes didn't help.?
Even though the clicks occur when moving the encoder, it was the display updates causing the noise for me. ?When I moved to a TFT or LCD display I didn't have this issue, but check that your voltage supply to the DDS is not under load, that could cause some noise on updates.
Hope this helps Darryl VK3DAZ
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On 24 Jan 2017, at 6:39 am, Jack Purdum via Groups.Io < econjack@...> wrote: All:
I have my B40 with Raduino display and it works as advertised. I am now trying to add my TFT display and DDS VFO, which is a AD9850, more-or-less the same as the VFO in the Forty-9er article (March, 2016 QST). I am using a rotary encoder to change the frequency, again the same as before. The processor is a Mega 2560 Pro Mini; too many things going on for a Nano. I've used the TFT display, DDS, and Mega boards on an antenna analyzer project and had no issues. (Schematic attached, the SWR bridge is omitted.) However, on the B40, any movement of the encoder can be "heard" in the receiver audio. Also, there is a slight dimming, or flicker, of the display when rotating the encoder.?
As I've said many times before, I'm a software guy so the EE stuff leaves me not knowing where to begin. Any ideas sincerely appreciated.
Jack, W8TEE
<Figure33.jpg>
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Re: Strong stations too loud even at lowest volume
Yes, when power to Q1 is switched off, that path is linear. But I am curious how big a signal it can pass as a linear amp when that pot is at 10k. I'd guess either your mod or the pot on the rx line between the relays would work fine, and either would be about as much trouble to implement. Agreed, feature creep on the rig as shipped from hfsigs should be avoided. ?But it's built to be hackable, adding AGC (with a disable switch) to see if you like it seems a perfectly fine way to spend the day. ?Those with strong signals popping up next door now and then might welcome AGC. ?I doubt I'll need it out here.
Jerry Gaffke, KE7ER, Flora OR
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All:
I have my B40 with Raduino display and it works as advertised. I am now trying to add my TFT display and DDS VFO, which is a AD9850, more-or-less the same as the VFO in the Forty-9er article (March, 2016 QST). I am using a rotary encoder to change the frequency, again the same as before. The processor is a Mega 2560 Pro Mini; too many things going on for a Nano. I've used the TFT display, DDS, and Mega boards on an antenna analyzer project and had no issues. (Schematic attached, the SWR bridge is omitted.) However, on the B40, any movement of the encoder can be "heard" in the receiver audio. Also, there is a slight dimming, or flicker, of the display when rotating the encoder.?
As I've said many times before, I'm a software guy so the EE stuff leaves me not knowing where to begin. Any ideas sincerely appreciated.
Jack, W8TEE
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Re: Strong stations too loud even at lowest volume
Good question Jerry. No, it just gets deaf(er). No extraneous products. With Q1 idle signals pass from C11 through R14 to C13. It would take nearly a volt to broach the barriers on the idle BJT. At that point it will distort no matter what. Certainly one could incorporate other measures but none would be so simple and effective. A FET between K2 14 and K1 12 could be controlled for AGC but that is a wee bit more work. No AGC is rather nice. Less background noise. CW is good without AGC. Beware Feature Creep!
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No shorts in the turns. I also re soldered the connections.
When I scope the transformer, I get 250mv p-p. Looks like one of the transistors is gone. I had it working for quite for weeks.
Checked my DDS setting drive source to 8ma,?crystal load to 8pf. Stuck a 50 ohm load on the o/p and I get 1.8v p-p.
73
Ken VA3ABN
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Re: Strong stations too loud even at lowest volume
I'm sure it works well enough. ?My concern is that the diode ring mixer is non-linear, but normally only the 40m signals from the antenna get passed on to the 12mhz crystal filter because the bandpass filter up front strips out everything except 40 meters. ?Now if Q1 goes non-linear, we've got all those 40m harmonics plus all the vfo harmonics mixing together, likely producing a few birdies. ?(That's just as true for those of you with carefully groomed sine waves out of the VFO, cuz the action of the mixer is very not linear.)
On Mon, Jan 23, 2017 at 08:04 am, Jerry Gaffke wrote: Does Don's trick of cutting power to Q1 make that first RX amp go non-linear, and introduce crud into the received signal? ?
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Look back at messages.? There was an email address that you send PayPay to and the serial? numbers of the boards. I just told them I needed 2 and sent the money PayPal. I put how many raduinos i needed in the comment/message box on PayPal. Got them In the mail a month or so later.? Jared
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On Jan 23, 2017, at 11:00 AM, "kq2q2000" < kq2q@...> wrote: Hello, I received a new BitX40 in December. I see that the 2017 units come with a Raduino DDS
I would like to order one or two Raduino's. How do I do that? I do not see them for sale on the webpage. Thank you, Bob? KQ2Q Danielsville, GA
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Re: Strong stations too loud even at lowest volume
Send an email to hfsignals at gmail dot com stating you're an old customer and would like the Raduino upgrade.. Do it now, they were offering the upgrade to old customers for $14, but seems they were cutting it off right about today.
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Re: Strong stations too loud even at lowest volume
Using a pot between antenna and ground, center wiper into the receiver, seems the most obvious thing. ?The ideal place for such an RF gain control would be in the wire between K2-14 and K1-12, an attenuator there will only affect the receiver. ?Pot should have short wires to it, or use coax. Should also work fine to put a 1k pot in front of C11, as output of the transmit amp at Q4 would then only see 1k to ground regardless of the position of the RF gain control. ?Also, that node is free floating with DC blocking caps in all directions. ?But can't be on the Q1 side of C11, as that would muck with the DC bias into the base of Q1. ? ? What's the best way to do AGC here, such that it affects the RF gain and not AF gain? Does Don's trick of cutting power to Q1 make that first RX amp go non-linear, and introduce crud into the received signal?
On Mon, Jan 23, 2017 at 05:42 am, Lawrence Galea wrote: The simplest way.A pot at the aerial input to the receiver side. 50¦¸, 100¦¸, 1k¦¸, 10k¦¸ whatever you have. Aerial input to the top, centre to receiver, other contact to earth. ?
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Hello, I received a new BitX40 in December. I see that the 2017 units come with a Raduino DDS
I would like to order one or two Raduino's. How do I do that? I do not see them for sale on the webpage. Thank you, Bob? KQ2Q Danielsville, GA
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Re: Strong stations too loud even at lowest volume
I bread boarded Peter's set up and it works great. The only variation I had was I put the LED and LDR in a sleeve of shrink tubing. (I bought a bag of the stuff at Dayton for next-to-nothing and I'm going to have to live to be 150 to use it all up. If it doesn't move and I can't eat it, it ends up in shrink tubing...)
Jack, W8TEE
From: Peter Parker <parkerp@...>
To: [email protected]
Sent: Monday, January 23, 2017 4:06 AM
Subject: Re: [BITX20] Strong stations too loud even at lowest volume
Another AGC idea. ? Uses an LED & LDR. ?Louder signals brighten the LED which reduces the LDR's value which reduces the volume, so compressing the audio.?
https://www.youtube.com/watch?v=IQ5JEPRiPoM
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Re: Strong stations too loud even at lowest volume
The simplest way. A pot at the aerial input to the receiver side. 50¦¸, 100¦¸, 1k¦¸, 10k¦¸ whatever you have. Aerial input to the top, centre to receiver, other contact to earth. Used it way way back and it works.? Low values are better.? Just try it.
V I ? ? ? ?Potentiometer? I ------- Antenna < > < ><---------Receiver input < > I ------- earth
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Re: Second tuning pot in analog
Bob,
A bourns 100K 10 turn pot will do a great job.
Alternatively use a pot of 10% of the value of the main tuning and
connect the center and end pin in series to the tuning pot.
Disconnect the earth end of original tuning pot.
Connect the end of fine tune pot to ground.
Connect the center of fine tune pot to the main pot disconnected earth
end.
If the tuning works reverse of what you expect then use the other end of
fine tune pot to ground.
That should do it!
At 23/01/2017, you wrote:
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How do you wire the second pot
in series?
72, Bob KI0G
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Re: Strong stations too loud even at lowest volume
R15 serves as part of the stage supply filtering. I would leave it. If you want to remove R16 then be sure to install a 220 ohm resistor in series with the switch or control. That will limit the current. A switch works very well, don't discount the simplicity and utility. I would recommend that you only do this at this one stage. The others need to provide the proper terminations to the crystal filter. -ND6T
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Re: Battery recommendation...with external amp
Sounds like I would be well off going LIPO, I don't want to go with an automotive or RV battery - I have to lug one of those when I go camping anyway, as I run a CPAP on an inverter when I am sleeping (if I start out fully charged it lasts a full weekend), but I really don't want to run my radio equipment off the same battery, for obvious reasons. If I can charge my radio battery packs off my car's battery overnight, then run the car engine for a bit to charge the car battery back up, or run a SMALL solar charger during the day to charge spare packs (big panels get expensive...), that would be fine as well. I live in northern Michigan so we don't get as much sun (or wind, most of the time) as the fellow in Texas does...
Rich KC8MWG
On Monday, January 23, 2017 1:12 AM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
If I had the motorcycle battery handy, I'd certainly use it. ?Check water levels occasionally if it has vent caps, especially if it's on the charger much. ?I even suggested somebody try a motorcycle battery here a few weeks ago when I thought they might be having trouble with their switching power supply. ?But they aren't built to give a lot of discharge cycles, and lithium is far better than lead if you are going to be lugging it around in a backpack. ?
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Don, ND6T
JP McGinley KA3BWP
Raj vu2zap