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Gigaparts has been out of stock for quite a while now.? I still have one on backorder, not clear when they'll be back in stock.

GF

Sajid Rahum,

There is a spreadsheet in the files section with voltages for the transistors.? Look for vu2zap in the files search.
/g/BITX20/files/VU2ZAP

The power sections of the different versions are the same, so the voltages should be correct or at least close.

73
Evan
AC9TU

All - looks like i lost output power on SSB.

Here is trace of what happened.? By mistake i had wrong antenna plugged in.

1. I will test CW output to see if there is any power after PTT on mic PTT.
2. PTT relay is kicking in with SSB; i am able to hear modulation on receiver nearby.

Could Q90 be gone? or IRF510?

for Q90 - what is the exact component or is there a substitute i could use.

Appreciate your inputs.

Well the traditional pair of diodes can be helpful. But the nifty thing about the led photoresistor AGC is that the attenuation comes from mere resistance so there is minuscule distortion. Howard has advanced it nicely for his ubitx by moving the tap after an added cw filter. I am pleased merely installed across the volume control. I am thinking it should work with the QCX but I haven’t done it yet.?

curt wb8yyy?

10, 15 and 20 have been open for me this morning, and my V6 uBITX has done a great job in netting me some contacts.

I am LOVING this radio!!!

John

Are you using the same USB cable for both in-circuit and out-of-circuit programming?? If not,
then the cable you are using for in-circuit may be a charging-only cable with no data leads.

Arv K7HKL
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_._

Noted Sir, let me get the spares within this week. Apparently it will take more than a week for the vendor to ship. So I am heading to "Lamington Road" and fetching stuff. My qth is on the other end of Mumbai.

Will keep every thing updated

Simran,

Here are the results of my quick test:
? ? ? ? ? ? ? ? ?Receive Current? ? ? ? ? USB Current? ? ? ? ?CW Current? ? ? ? CW Power Watts
12 volts? ? ? ? ? ?0.427? ? ? ? ? ? ? ? ? ? ? ? ? 1.5? ? ? ? ? ? ? ? ? ? ? ?1.77? ? ? ? ? ? ? ? ? ? ?3.9
13 volts? ? ? ? ? ?0.433? ? ? ? ? ? ? ? ? ? ? ? ? 1.6? ? ? ? ? ? ? ? ? ? ? ?1.86? ? ? ? ? ? ? ? ? ? ?4.9
14 volts? ? ? ? ? ?0.441? ? ? ? ? ? ? ? ? ? ? ? ? 1.7? ? ? ? ? ? ? ? ? ? ? ?1.93? ? ? ? ? ? ? ? ? ? ?6.0

All Current is in Amps
The frequency was 14.030 MHz
I used a GRPGuys SWR/Power/50load on the output for the power measurement and the dummy load.
There was no sound into the mic for the USB test.

NOTE:? I did not set up this rig.? My stock uBitx is on loan to a fellow ham to see how it works for CW (I am not a CW operator).? I am not sure why the USB current is so high.? If my memory serves when I did the stock uBitx it was around 0.9 amps (.7 without any bias).??This uBitx is not stock: The Raduino and Nano have been replaced with a Teensy board version.? This should only affect the total current draw, not the difference between the receive and the transmit.? It should still be in the ballpark.? Because it is not stock I did not want to raise the input voltage above 14volts.

You can see that the efficiency is not near 50%.? It is more like 19% to 22%.

On 80 meters with 12 volts in:
? ? ? ? ? ?Receive Current? ? ? ? ? LSB Current? ? ? ? ?CW Current? ? ? ? CW Power Watts
? ? ? ? ? ?0.429? ? ? ? ? ? ? ? ? ? ? ? ? 1.5? ? ? ? ? ? ? ? ? ? ? ? ?1.92? ? ? ? ? ? ? ? ? ? ?6.9

The above is for reference.
73
Evan
AC9TU

Dear Evan, thanks for the reply. Sure thing. Please take your sweet time. In the mean while I will refer the voltage chart as provided by Raj VU2ZAP and see.

I was wondering if i should inject a 20mV 1kHz signal to the mic preamp and see the output?

thanks
Simran

On Sun, Dec 19, 2021 at 09:27 AM, <arorasimran@...> wrote:

I will recalc for 15V. It will be some what relatively less but should be in the same ball park.

Simran,

The power does not remain constant.? It is better to think of the IRF510s as variable resistors that the resistance is dependent on the gate voltage.? This is not related to the voltage on the drain.? What that means is the current will INCREASE with voltage increase.? This is why some run their rigs at higher voltage; to output more power.

I have to run errands right now but will set up my v6 to measure the current draw change between transmit and receive when I get back.

73
Evan
AC9TU

Thanks Paul for the information. Can you please tell me what current it draws or it should draw generically on 80m and 20m with your voltage setup. I will recalc for 15V. It will be some what relatively less but should be in the same ball park.

I don't really think any thing will go wrong with 15V, I remember I had definitely tried to tx on a wire antenna without knowing SWR of the antenna whatsoever. That must have damaged the IRFs

I will do voltage measurements and get back.
The IRF will get delivered some time this week tomorrow onwards.

WIll keep the thread updated.

Thanks

Simran

On Sun, Dec 19, 2021 at 05:20 AM, <arorasimran@...> wrote:

Can you please tell why should I lower this to 12V? it works well @ 15V (hopefully not frying the finals).

I just use 2 diodes (1N5400) to drop 15 volts to 13.5 volts.? I don't know what would be damaged by the 15 volts.

I do not have inline power meter so measuring DC current in series is only? my option.

The current pull is same on all bands

The ubitx will pull more current on the lower bands because it puts out a lot more power on 80 meters than 20 meters (for example).? On 10 meters, the current draw will be much less than on 20 meters.? So something is seriously wrong if the current draw is the same on all bands.

Maybe take voltage measurements and troubleshoot it that way.? Someone uploaded a voltage chart in the files section.

Dear Farhan bhai, it pulls around 1.02 amp peak to 0.98A quescent

Hi there Ashhar bhai, Salam Namaste, No I cant really check that. No knowns in the vicinity to really test this.?
Do you think I have fried the finals?

Dear Paul, thanks for replying and helping.
I will definitely first get a dummy load. Possibly, I have a SDR that can do HF? monitoring. No other radio as such to monitor.

Can you please tell why should I lower this to 12V? it works well @ 15V (hopefully not frying the finals).

The only goofup I did was while assembling the kit, I connected LS to the wrong port and hereby frying a diode that refers to battery operation ? if I am not wrong?
I have ordered 10x IRF510s and will try my best to not fry them with ESD :D

The antenna SWR was measured using my RigExpert analyzer.

I do not have inline power meter so measuring DC current in series is only? my option.

The current pull is same on all bands

On Sun, Dec 19, 2021 at 03:21 AM, <arorasimran@...> wrote:

Also, with CW its 1A @ 15V =15W consumption. With voice 0.7A @ 15V = 10W.

That 1 amp current for cw transmit is low.? Not normal.? Should be at least 2 amps (or more).? Troubleshoot this first.

Can you try transmitting on a lower band and look at the current on CW transmit?? The current should be higher on lower bands.

Do you have a radio to monitor your transmission?? No antenna needs to be connected to the monitoring radio.

There are a lot of great suggestions in this thread - get a dummy load, add 3 diodes to lower the 15 volts, replace q10 with 2n2222.