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Re: No audio driver
Could use the diode probe if a signal is injected into the amp with some kind of probe, giving a response 2 or 3 ?times bigger than it normally is. On Sun, Apr 2, 2017 at 06:01 am, Ashhar Farhan wrote:
The difficulty with a good procedure to align the the tx is that, it needs to 'see' the RF at fairly low levels of 100 mv or so. ? |
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Re: New to group -- exploring multiband capabilities
I've heard that using CLK0 and CLK2 with CLK1 forced low does alright. ?Turning on CLK1 to use all 3 does create some crosstalk as they are all operating from the same VCCIO supply. ?Ashhar apparently found that not to be a significant issue on the uBitx, though if not to your taste you could spend another $1USD on a second Si5351 (and figure out some way to talk to the second I2C port). ?A VXO on the BFO works, but having an Si5351 channel for the BFO makes it easily adjusted for alignment and USB/LSB/CW selection. ?The Si5351 only has two PLL's internally, but the fractional dividers on the outputs allow more than enough resolution for our purposes. Exactly how would you use CLK2 for GPS calibration? ?I'm thinking the ideal (and cheapest) way to calibrate is to set it up as a 10mhz WWV receiver (or your favorite HF time standard signal at most any frequency), look for zero beat. ?That zero beat will depend on all three uBitx local oscillators, but since they are all operating from the same reference oscillator the calculations for the correction factor are trivial. Jerry, KE7ER On Sun, Apr 2, 2017 at 06:23 am, cove37 wrote:
I'm also guessing someone's solved the interrelational problems with clk1 and 2 to get the desired frequencies from all 3 outputs. ?I still would be ok with using a VXO for the BFO so I could use the clk2 for GPS calibration. ? |
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Re: No audio driver
If you now have no output when you speak into the mic, but the receive is OK (but everything worked OK previously); then another component to check is Q13. Although Q13 is in the TX path, it is left in the circuit during RX. If you have transmitted on another 100W or higher power rig while the Bitx40 was in RX mode on a nearby antenna,then there is a good chance you have blown Q13 - if you didn't install the two 1N4148 protection diodes between K1 pin 12 and ground. The picture in the following message shows the location on the board: /g/BITX20/message/22844?p=Created,,,20,1,0,0::Created,,minimum+mods,20,2,40,4415405 Placing them between pin 12 and ground means they are only in the circuit during RX; you might not want an extra couple of non-forward biased diode junctions in the TX path during transmit that could generate noise, harmonics etc. Q13 can be replaced by a 2N3904. |
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Re: New to group -- exploring multiband capabilities
Thanks for the info. ?The uBitx system looks promising also. ?If no one is having problems with the 12mhz IF, then I'll stick with it. ?10.7 is convenient because you can buy matched crystals for that freq off the shelf. ?I'm also guessing someone's solved the interrelational problems with clk1 and 2 to get the desired frequencies from all 3 outputs. ?I still would be ok with using a VXO for the BFO so I could use the clk2 for GPS calibration. Thanks Burton Ison W5IAC On Saturday, April 1, 2017 4:06 PM, cove37 via Groups.Io <cove37@...> wrote: Hello all, A couple of questions to bounce off all -- since the IF is 12Mhz (maybe change to 10.7 to get it further from 20m), couldn't 20-10 meters use the mixer sum, instead of difference, and this would automatically switch the sideband to upper? ?Also, would it simplify the filtering to use a robust bandpass filter for each band for both T and R, eliminating the need for a separate LPF? Thanks Burton Ison W5IAC
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Re: No audio driver
The transistor current stays the same in all the class A amplifiers. It won't do. It should be something simple that is available in every shack. probably, a slightly forward biased diode will do it. - f On Sun, Apr 2, 2017 at 2:50 PM, Lawrence Galea <9h1avlaw@...> wrote:
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Re: Raduino BFO hook up?
Does anyone know of Arduino code that works on a Arduino with an encoder that handles 10 MHZ and below (LSB) and above USB with the correct frequency readout? The Pa3fat code I am using works well below 10 MHZ but 20 meters I am at 9MHZ and tuning is backwards (when display shows going up in frequency.. Output is actually going down) which makes converting tuff!
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Re: SOLVED Re: [BITX20] Bitx40 low volume oscillation squeal
Nothing strange in electronics On Sun, Apr 2, 2017 at 1:51 AM, Graham <planophore@...> wrote:
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Re: No audio driver
Farhan how about measuring voltage changes in supply or emitter resistors? Regards Lawrence On Sun, Apr 2, 2017 at 8:54 AM, Ashhar Farhan <farhanbox@...> wrote:
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Re: No audio driver
How about this Farhan?
toggle quoted message
Show quoted text
It should do, very economical RF probe! 73 Raj At 02-04-2017, you wrote:
I am trying to figure out a simple tx checkout procedure that doesn't need, say, "connect a 1ghz spectrum analyzer to point x".? |
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Re: No audio driver
I am trying to figure out a simple tx checkout procedure that doesn't need, say, "connect a 1ghz spectrum analyzer to point x".? The difficulty with a good procedure to align the the tx is that, it needs to 'see' the RF at fairly low levels of 100 mv or so. This is quite difficult with a simple diode probe. The diode probes work only above 1v levels. One could add an RF amplifier to boost up the levels, but that is just too much complication. does anyone have a better idea of a simple 2-3 component rf detector? - f On Sun, Apr 2, 2017 at 7:49 AM, John Backo via Groups.Io <iam74@...> wrote: Mike. please realize that the hfsigs group aligns the BITX40 for RX (to 40m), but does NOT do any TX alignment. |
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Re: Adding speech compression.
Hi John, Adding speech compression can make a difference when trying to cut through noise or a heavy pileup, but tread lightly; it's easy to turn your good intentions into over-modulation or worse.? Here's a bit of introductory reading to get you started (be sure to check out the references): |
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Re: No audio driver
Mike. please realize that the hfsigs group aligns the BITX40 for RX (to 40m), but does NOT do any TX alignment.
There is one reference to TX and that is to increase the rig current by 100ma. with the PA connected. Transmit involves the audio mic amplifier, the PA drive, and the PA output voltage. Most likely the mic audio is ok, if connected properly. But the IRF510 gate voltage and the PA drive need to be set for proper operation. This involves adjusting RV1 AND R136. Set the current up 100 ma. with the IRF510 connected. This is done by adjusting RV1. NOTE WELL that the gate voltage on the IRF510 should not exceed 4v. or so. Then, with the mic connected, try speaking into it in TX mode. Observe the current draw of the IRF510. It should increase to about 1 amp or so. If it does not, the first thing top try is an adjustment to R136. Slowly increase R136 (the PA drive) until you see an increase in the current draw on transmit. This is the proper procedure to get into TX mode. See the Topic "BITX40 Low Output Power" (message 23134 and following) for more information. Jerry, perhaps a short paper on transmitter adjustment is in order? It should be on the same page as hookup information. john AD5YE |
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Re: extra surface mount component
y Bit The leaded ceramic disk marked 106 is not a mystery, that's called out in the destructions at ???
The SMD 0.1uF cap is still a mystery. ?There were lots of ripped out C107's for some obscure reason, my best guess is the SMD cap is a replacement C107. ?But would not be a bad idea to put a 0.1uF cap on both ends of the tuning pot wires, one at the pot and one on the raduino. ?The raduino end may be the more critical. Jerry, KE7ER On Sat, Apr 1, 2017 at 06:50 pm, <ae6d@...> wrote:
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Re: extra surface mount component
I received my BitX40 two days ago. The box contents (item 16) lists the 1 x 0.1uf smd capacitor. It measures at 88.5nf with my cheap tester. There is also a loose ceramic capacitor with leads (104) in the box which is not in the box contents list. It measures at 72nf. Both are roughly the 0.1 uf value. I thought maybe a choice of two types of capacitors. I don't have a new guess on what they are for. My board has an intact C107. I first thought one might be for the 2nd harmonic suppression (see the "bitx output harmonics" thread. The fix for the harmonic problem is a 100 pf capacitor, not 100 nf, so I don't think it is for that. I'm not far enough along to see if mine has a 2nd harmonic problem. Ed, AE6D |
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Re: SOLVED Re: [BITX20] Bitx40 low volume oscillation squeal
Graham
¿ªÔÆÌåÓýHi Raj,I found that my problem was with the connector I had used for the volume control. There was some form of oxidation one the spring "pins" in the connector that was causing the audio stage to oscillate when the volume control as at or near zero ohms. A different connector and wires and all was better. I have seen some strange things before but this was a first. cheers, Graham ve3gtc On 2017-04-01 10:50, Raj vu2zap wrote:
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Raj vu2zap
Goran VE6GPO