Good point Evan!
But I can’t figure out is how disconnecting a Lowpass filter would result in a lower voltage. It should result in a higher voltage. ?
I tried to look for what things might be shorting out. There’s a chance that the high-voltage system is shorting out but it’s only connected by 47 pf?
?and that’s not much. ?
Gordon?
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On Feb 28, 2025, at 16:35, Evan Hand via groups.io <elhandjr@...> wrote:
? It should be possible to test the LPF selection process with a DMM.? Use USB, set the drive to 1 and the mic to 0.? Then, measure the voltages on the banded sections of the selection diodes.? Only one pair should be close to zero; the others should be close to the input voltage (12 volts) without the RF voltage doubler.
?
73
Evan
AC9TU
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Re: uBITX v6 Low Audio - Back at it again
Sorry, my bad. It is 0.82 kOhm, not 0.82 as reported. Thanks for catching that. Base of Q30 is in fact 50.8 ohms. i rechecked. OK, C30 will get removed and voltages checked on Q30. 73, Richard AG5M
On Friday, February 28, 2025 at 12:38:02 PM PST, tomekdm sp7etd via groups.io <tomekdm@...> wrote:
Hi Richard,
Really sorry, my mistake, I have measured C10 again to the ground and this is also ~823 ohm.
But don't bother with C10, nor C30. This is the same as measuring resistance from base of Q10 and Q30 to GND.
In both there is ~823 ohms. Your measurements brings confusion as I was thinking we have only trouble at 2nd RX chain,
are you sure its not 0.82 kOhm? If this is 0.82k then its OK.
Anyway 50 ohm on base of Q30 is NOK.
Can You de-solder C30 and measure voltages on Q30 before replacing Q30?
Regards
Tomasz
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Re: zBitx - Progress Update
The USB ports are the actual USB ports on the Raspberry Pi Zero 2, so HFSignals didn't have much say in it.
?
Joel
N6ALT
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It should be possible to test the LPF selection process with a DMM.? Use USB, set the drive to 1 and the mic to 0.? Then, measure the voltages on the banded sections of the selection diodes.? Only one pair should be close to zero; the others should be close to the input voltage (12 volts) without the RF voltage doubler.
?
73
Evan
AC9TU
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Re: zBitx - Progress Update
So, the USB port is microUSB, not USB-C? A little disappointing, but I guess the C is larger and there wasn't room?
The rest is very exciting, and I'm waiting with bated breath for mine! -=-=-=-=-=-=-=-=- 73, Gwen, NG3P
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“Is it possible that the software got crazy and didn't enable any section in the LPF filter?
73,
奥辞箩迟别办”
It’s unlikely that the software is doing anything wrong. It’s more likely that some piece of hardware has a problem in order to figure that out. We have to divide this somewhere and decide whether the problem is on the left side or the right side. With your voltmeter, unable to measure DC voltage properly in the face of RF, this is going to be a little more difficult and may require the scope.
But the first problem is probably to split this into modules and figure out where the issue is : with the transformer or beyond that.
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Re: Has anyone received a zBitx?
Please see this message for more information, it was sent earlier today:
?
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The below message was an answer to sa7buj.
As shown in the scope image, I have ca 4.5V peak-to-peak there when transmitting.
-- Wojciech M. Zabo?otny
My GPG/PGP keys:
standard: 8192R/7E17F00A (B53C 1F09 BEA9 ED46 51B6 ?2C2E 4344 F292 7E17 F00A)
confidential: 16384R/1FEDB03C (3412 2330 E225 D57D 70C3 ?2340 B294 9408 1FED B03C)
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Re: Has anyone received a zBitx?
HI Jim -- this has been explained in recent messaging.? ?Take a read and you'll learn everything you are asking. 73 KX4Z
Hey everyone,
?
Since we're at the end of February.? Just wondering if anyone received their zBitx yet.? any reviews etc.? If not is there a date when they will be shipped/Delivered and available for order again?
?
KD9QPD
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Has anyone received a zBitx?
Hey everyone,
?
Since we're at the end of February.? Just wondering if anyone received their zBitx yet.? any reviews etc.? If not is there a date when they will be shipped/Delivered and available for order again?
?
KD9QPD
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Re: Looking for the V2 Hardware Upgrade Info
I misunderstood you, I thought this was what you was searching for. Swing and a miss I guess. Haha
David
On Fri, Feb 28, 2025 at 06:14 AM, WK4DS wrote:
Here you go JJ
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I was finally able to return a small favor for all your hard work on these awesome radios…
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David
WK4DS?
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Thanks David. Although this doesn't address the necessary upgrades to keep the IRFZ24Ns in place; it does help to convert a V2 to a V3.
?
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As shown in the scope image, I have ca 4.5V peak-to-peak there when transmitting.
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Is it possible that the software got crazy and didn't enable any section in the LPF filter?
?
73,
Wojtek
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Re: uBITX v6 Low Audio - Back at it again
If after de-soldering of C30 voltages on Q30 will be near voltages of Q10, so:
E= 1.6, B= 2.4, C= 7.9
Then You need to replace C30 with any 100nF (0,1uF) ceramic capacitor.
?
If voltages will be still low as before:
E= 0.0, B= 0.28, C= 11.00
Then Q30 needs replacement.
?
Regards
Tomasz
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Re: uBITX v6 Low Audio - Back at it again
Hi Richard,
Really sorry, my mistake, I have measured C10 again to the ground and this is also ~823 ohm.
But don't bother with C10, nor C30. This is the same as measuring resistance from base of Q10 and Q30 to GND.
In both there is ~823 ohms. Your measurements brings confusion as I was thinking we have only trouble at 2nd RX chain,
are you sure its not 0.82 kOhm? If this is 0.82k then its OK.
?
Anyway 50 ohm on base of Q30 is NOK.
Can You de-solder C30 and measure voltages on Q30 before replacing Q30?
?
Regards
Tomasz
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Wojtek, the scope photos were very helpful.
?
That transformer is supposed to Step UP the voltage, not down.? ?So something is terribly wrong, and it appears tht bothof your FETs are doing fine.
?
You can divide the system in half and help to figure out where the real problem is, by lifting the Orange wire that goes to the CAPACITORS and send it instead to a 50 ohm dummy load of suitable power handling capacity.? ?Then measure the voltage or power in that line.? ?Of course it will have sizeable HARMONICS so you dont' want to send it to an antenna, but sending it to a dummy load will allow you to check that the transformer is still working properly.? ?You should get PLENTY of power out of the orange wire.? ??
?
Assuming you DO get power out of the Orange wire -- then the problem is in the LPF system; something is indeed shorting out your power.
If you do NOT get power out of the Orange wire -- then there is something wrong with the transformer.? ?I didn't see enough in your tofigure it out.? ?It should have two brass rods that are probably soldered together on one side and not on the other, but I'm not able to see mine and not exactly sure how they are assembled.
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Splitting the system into? ?MOSFETS+TRANSFORMER? one one side and? LO PASS FILTERS out of the question will help you figure otu where the problem lies.
?
73
Gordon KX4Z
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Re: Looking for the V2 Hardware Upgrade Info
This is from Farhan re upgrading my V2, "The standing current in the diodes that switch the LPFs was found insufficient on 3.5 MHz, hence, the resistors R201, R202,
R203 and R204 are changed from 470 ohms to 330 ohms."
?
Joel
N6ALT
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Re: Looking for the V2 Hardware Upgrade Info
Joel,
?
FYI, changing the resistors increased the bias current on the PIN diodes for the LPF and T/R switching diodes.? This was to reduce spurs and improve power output,
?
73
Evan
AC9TU
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Re: Looking for the V2 Hardware Upgrade Info
One of the things to change is R201-R204 to 330ohm 1/4 resistors, I remember doing mine but I don't remember why, other than that I don't recall doing anything else.
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Joel
N6ALT
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Re: uBITX v6 Low Audio - Back at it again
Before I stat removing components, I'll report the following based on your last suggestions:
Resistance from base of Q30 to GND = 50.8 ohms, no where close to 836 ohms.
Resistance from base of Q10 to GND = 0.82 ohms, no where close to 102 ohms.
Resistance across C30, in circuit, = 50.6 ohms.
I light of that, what's your opinions? Start pulling and ordering some parts?
73, Richard AG5M
On Thursday, February 27, 2025 at 07:15:47 AM PST, tomekdm sp7etd via groups.io <tomekdm@...> wrote:
ok. got some measurements. While measuring resistance from base of Q30 to ground (top node of C30 to GND) is around 836 ohm. While base of Q10 to GND (top node of C10) has 102 ohm (different transformer). Richard, if You will have much lower than 100 ohm - C30 (100nF) is also suspected to have short.... less than 90 ohms.
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Richard AG5M
Joel Caulkins/N6ALT
Gwen Patton
WK4DS
tomekdm sp7etd