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Re: Homebrew from scratch
#ubitx
Richard Bennett
Very nice,
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I much prefer the modular designs for anything. I am thinking tho, when I take on an endeavor such as this, I would prefer to stack the boards in the box veetical? on their sides. Could still pack it in a pretty small enclosure. Just me thinking out loud. 73, KD9BPY
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Re: LA4425a Audio power IC
Looks like a good choice.
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Though?is now going obsolete (at least for ON Semi), which is true of just about every audio amp that's ever existed except for the LM386. Somehow, the LM386 just keeps chugging along. ? On Mon, Jun 18, 2018 at 11:41 am, R. E. Klaus wrote:
Curious if anyone has tried the LA4425a IC for replacement of the TDA2282. The LA4425a is used by Yaesu in some of their radios and needs only 3 external components, 2 of which are already in place in the uBITX and they are good up to 16 volts. They can be bought for a little over a dollar (U.S.) from UT Source and other internet dealers. |
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Re: Transmit indicator light.
Phase is important, if you are measuring current and voltage at the antenna port
you will also want to measure the phase angle between the two. A Tandem Match more or less measures voltage and current into the antenna. This one is $12:? ? ?? T1 is a current transformer, T2 is a voltage transformer, Actually, a Tandem Match adds the voltage and current readings in phase and out of phase from which an SWR relative to 50 ohms can be calculated. From those readings, can also calculate forward and reverse power in Watts.. Primary trick on a Tandem Match is that the voltage and current are scaled such that if driving a 50 ohm load, the sum of the two when out of phase is zero.?? The Bruene and Monimatch designs do about the same as a Tandem Match.?? This 1959 Bruene article is a classic, recommended:?? Here's a full analysis of the Tandem Match:?? Another tutorial on SWR meters:?? There are others. An advantage of the Tandem Match is that the transformer ratios pretty much calibrate it for both absolute power into 50 ohms, and SWR.? Unlike the resistive bridges typical of qrp swr meters, a Tandem Match (or Bruene or Monimatch and friends) can remain inline to monitor correct antenna functioning while operating the transmitter. If you really want to explore antenna impedances to 440mhz and maybe do two port measurements, check out?Kee's AQRP Vector Impedance Analyzer near the bottom of this webpage: ? ?? That one really does measure voltage and current into the antenna, along with the phase angle. And can do much much more. Jerry, KE7ER ? On Mon, Jun 18, 2018 at 11:10 am, Arv Evans wrote: Probably could use a diode rectifier and filter cap at the toroid location and run
DC to the front panel LED.? I have never tried that because radiated RF inside
the chassis has never been a problem.
Using a rectifier and filter cap could also let you measure RF current on an ADC
input of the Arduino.? Interesting thought that if you measure RF current and RF voltage at the antenna jack it might be possible to calculate antenna impedance.? |
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Re: Nextion Display vs 1602 LCD - Current Consumption
#ubitx
Jack Purdum
Most TFT color displays will run more current. Out 5" display runs as high as 0.7A. Jack, W8TEE
On Monday, June 18, 2018, 2:51:26 PM EDT, Joe <joeman2116@...> wrote:
I have a 3.28 Enhanced version on my ubitx. When I first installed it I noticed it ran warmer than with 4 line lcd display. I have a heatsink on the raduino regulator so it was warm but not excessive. However, with no display it was very cool. Most of us agree it would be best to use 5v from another source like one of the small adjustable 5v 1amp units on ebay Especially if your using the large display. With the 5v regulator ebay module as source, the raduino regulator barely has any detectable heat. Joe VE1BWV On Mon, Jun 18, 2018, 12:47 PM Michael Babineau <mbabineau.ve3wmb@...> wrote: As it appears that the Nextion Display will be getting its +5V from the L7805CV regulator on the Raduino board, I started wondering |
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Re: Nextion Display vs 1602 LCD - Current Consumption
#ubitx
I have a 3.28 Enhanced version on my ubitx.
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When I first installed it I noticed it ran warmer than with 4 line lcd display. I have a heatsink on the raduino regulator so it was warm but not excessive. However, with no display it was very cool. Most of us agree it would be best to use 5v from another source like one of the small adjustable 5v 1amp units on ebay Especially if your using the large display. With the 5v regulator ebay module as source, the raduino regulator barely has any detectable heat. Joe VE1BWV On Mon, Jun 18, 2018, 12:47 PM Michael Babineau <mbabineau.ve3wmb@...> wrote: As it appears that the Nextion Display will be getting its +5V from the L7805CV regulator on the Raduino board, I started wondering |
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LA4425a Audio power IC
R. E. Klaus
Curious if anyone has tried the LA4425a IC for replacement of the TDA2282. The LA4425a is used by Yaesu in some of their radios and needs only 3 external components, 2 of which are already in place in the uBITX and they are good up to 16 volts. They can be bought for a little over a dollar (U.S.) from UT Source and other internet dealers.
73, Roxie K1AUS |
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Re: Transmit indicator light.
I bet that someone? could come up with a circuit of a diode, capacitor and resistor to feed into the same analog pin as the s-meter in the modified software so you could see about how much power was going out. Seems simple enough to me, but I do not have the coding skills to do that. On Mon, Jun 18, 2018 at 2:10 PM, Arv Evans <arvid.evans@...> wrote:
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Re: Transmit indicator light.
Roy WA0YMH Probably could use a diode rectifier and filter cap at the toroid location and run DC to the front panel LED.? I have never tried that because radiated RF inside the chassis has never been a problem. Using a rectifier and filter cap could also let you measure RF current on an ADC input of the Arduino.? Interesting thought that if you measure RF current and RF voltage at the antenna jack it might be possible to calculate antenna impedance. Arv? K7HKL _._ On Mon, Jun 18, 2018 at 11:48 AM Roy Appleton <twelveoclockhigh@...> wrote:
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Re: Transmit indicator light.
The following is a question not a statement. Typically the ant lead is at the back of a radio case and the LED indicator would be on the front panel. Wouldn't running the wires feeding the LED that distance cause a potential of rf radiation into the radio? Roy WA0YMH On Mon, Jun 18, 2018, 10:47 AM Arv Evans <arvid.evans@...> wrote:
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Re: Damage to uBITX from nearby QRO transmitter (no power out on TX) ?
#ubitx
Jerry, thanks for the heads up on msg #37380. Somehow I missed that discussion late last year.?
I don't recall anyone postings about problems with Q90 on the uBITX and given the number of "blown" Q13s in the BITX40, either people have become more cautious (unlikely), or as Farhan suggests, the first diode ring mixer is offering enough protection. As they say, "if it ain't broke, don't fix it" ! Cheers Michael VE3WMB? |
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Re: Low RX Audio
#ubitx
Have a usb oscilloscope with built in dds. Will check today. Thanks for the idea. |
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Re: Damage to uBITX from nearby QRO transmitter (no power out on TX) ?
#ubitx
The incandescent lamp is good because resistance of the filament increases by 10x as it heats up.
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Here's an old thread on that:? ?/g/BITX20/message/31352 The back to back diodes on the uBitx may not be a good idea however, as they could introduce spurs as stated in my previous post. Jerry, KE7ER On Mon, Jun 18, 2018 at 09:28 am, iz oos wrote:
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Re: Damage to uBITX from nearby QRO transmitter (no power out on TX) ?
#ubitx
A fix was earlier suggested for this. let us check Regards MVS Sarma ? On Mon, Jun 18, 2018 at 10:03 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote: Very few reports here of Q90 on the uBitx getting blown. |
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Re: Damage to uBITX from nearby QRO transmitter (no power out on TX) ?
#ubitx
Very few reports here of Q90 on the uBitx getting blown.
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Q13 was getting fried quite often on the Bitx40. Farhan figures that front end protection diodes will create lots of extra spurs, and that the first diode ring mixer offers adequate protection. ? ??/g/BITX20/message/37380 Worth experimenting with.? Jerry On Mon, Jun 18, 2018 at 07:05 am, Michael Babineau wrote:
Has anyone reported damage to their uBITX (little or no power out on TX) caused by previously keying a QRO rig nearby ?? |
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Re: Damage to uBITX from nearby QRO transmitter (no power out on TX) ?
#ubitx
You can put a very small lamp in series before the back to back diodes, to increase protection. Consider however that diodes would add some overload. Il 18/giu/2018 16:05, "Michael Babineau" <mbabineau.ve3wmb@...> ha scritto: Has anyone reported damage to their uBITX (little or no power out on TX) caused by previously keying a QRO rig nearby ?? |
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Re: Help with AGC kit wiring
Don is out of town for the 4th and he can provide nice looking drawings. I probably need to put "snaps" on my board as often as I've taken it out of the unit.
However the picture associated with?#49378? gives you a rough idea (but uses 2 pins and is less mechanically secure).? This is for the Ver 3 uBITX board. I understand there are some differences between it and the Ver 4 uBITX board but i don't have one to check. Hopefully this will help clear up the questions: 1) remove a 0.2" section of the trace where you want to install the AGC 2) scrape the solder mask off the trace ends and prepare them for soldering by tinning them 3) drill a header pin size hole in the middle of the 0.2" section you removed. It will go through the ground plane on the other ? ? side of the board. 4) scrape the solder mask off around the hole on the ground side. That is where the middle header pin will be soldered. ? ? Requires lots of heat because the hole will haver no thermals.? 5) take a 3 pin section of male header and bend the short leads out at right angles (in the same plane as the rest of the ? ? header pins to match the tinned trace ends when?you insert the middle pin in the hole you drilled. 6) solder the 3 pin header in place ....you can add super glue if you want but not necessary. 7) solder a 3 pin section of female header to the AGC board. Note the pins are labeled "IN" (to K3 pin 14) and "OUT" ? ? (to K1 pin 12).The connector can be mounted parallel to the AGC board (bend the pins 90 degrees) which?results in ? ? the AGC board being plugged perpendicular to the uBITX board or at right angles which results in the AGC ? ? board being parallel to the uBITX board. Make sure there is no interference (shouldn't be). 8) the rest of the wiring can be attached to the top or bottom of the AGC board .....your choice. 9) you can use a RF Gain pot or jumper that function out (jumper location is labeled and provided) ....your choice 10) you can use an "AGC hold time" jumper (provided) manually or add an AGC "Off, Fast, Slow" switch and wire it over ? ? ?to the?double row header.....your choice. The higher the resistance, the longer the AGC Hold Time. 11) you can add a S-meter connection as explained by Don.....your choice. 73 Kees K5BCQ ?? |
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Re: Transmit indicator light.
_._ On Mon, Jun 18, 2018 at 8:07 AM Praba Karan <vu3dxr@...> wrote:
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Nextion Display vs 1602 LCD - Current Consumption
#ubitx
As it appears that the Nextion Display will be getting its +5V from the L7805CV regulator on the Raduino board, I started wondering
if this regulator is up to the task (it is rated at 1.5 A) and if so whether or not this might mean that adding a heatsink to the regulator might now be a must (mine already runs pretty hot).? First I took a peek at the datasheet for the existing 1602 Display. The VISHAY datasheet that I had previously downloaded shows that? the Supply current (IDD) is only 3mA but it also lists LED forward current (IF) Array: 260mA Edge: 40mA (these are the Max values). So I am assuming that this means that the worst case current draw for the existing uBITX display is 3mA + 260 mA + 40mA which would be 303 mA ?? If this assumption is correct then the average current would be around 152 mA for the existing 16x2 Display based on average numbers (1.2mA + 130mA + 20 mA).? Looking at the specs for the Nextion 2.8 inch display () it claims that for a VCC of 5V and a Brightness of 100%? the? typical current draw is 65mA !? This seems too good to be true.? Unless I am missing something, this would mean using the Nextion would provide about 82mA current savings over the existing LCD display.?? Michael VE3WMB? |
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