Your results are disappointing as I'd suspected they would be.

The amplifier chain seems ot struggle to make power and the quality
of the power is poor.

What also is suspect is the two IF stage 12 and 45Mhz have excess
gain and the mixers are likely getting over driven.? How much excess
depending on how you count it overall at least 16db.? I don't believe
that helps except to make up for low gain in the transmit chain.

Allison

I have a v3 uBitx that has had some issues in the past but these were all worked out, to include changing out the TDA2822 to another version of that chip. I have been working with this radio for several weeks now and it has been working fine.
Today when I went to use it, the receive audio is extremely low. I can hear it in an earbud if I turn it all the way up, but the side tone is so loud then that you can't stand it. I havent made the side tone volume fix yet. The output is at rated output on CW but I have zero output on SSB. The rig was off all day and when I turned it on, this is what I found.
Then antenna is good, everything seems to check out fine except the radio. Can someone point me in the right direction?
Thanks
72



--
72 and God bless
KD4EPG

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Quick answer: Michael, you can set that frequency range anyway you want. ?It’s been along time since mine was stock, but I think it easily did the 40 m band.

I quickly took information from others and created my own little sketch that allows me to do 80 m as well, made a few hardware changes for that and bought an output low pass filter. ?

?I built my Bit40,? but was looking to find some specifications.? Is there a good list of specifications???? The HF Sigs site has some for the uBitx but missing on the Bitx40.?? For instance what should be the frequency range, bottom to top end???? I wanted to know if it goes to the right limits on both end.? Just some verification before I do any mods.

Thanks
73, KM4OLT
Michael

Hi,

If I recall correctly the forty meter filter also passes 30 meters, and the 20 meter filter includes 17 meters. The materials are starting to arrive for my external filters and I intend to build one for each band and not include two bands per filter.

73,

Bill KU8H

--
bark less - wag more

sweep of L17, L18, L19?

Yes, corner is set a high so it can be used on 60m too.

Aha!!!! photo of "80 meter" bandpass filter on my ubitx ...L20, L21, L22 as swept? ..corner frequency is closer to 6 mhz than 4

Jim

Hi, I try to explain that happend to my uBitx, in 40 m dont have trouble , the signal its strong, but when advance in superior bands 20, 15, 10, the noise its very low, I supose was the antenna, but prove with ft-817 and have a strong signal in this bands, I try the BFO settings, gain some signal streng in 20 m no more, any ideas??, Sorry for my English, 73 from Chile.

Punctuation, lad! For lack of a comma, it reads as JW4JM. Still, a neat call. My previous, a selection from those available, was ZL3LH (different region, and vanity calls not implemented in regulations), 'Left Hand' to balance me (dexter being Latin for the right side/hand/arm: skill and sword-arm strength). Present call is a 'vanity', and quite pleasantly fluid to the 'fist'...
73 de ZL2DEX

Allison

I may have needed to define my terms better. It was not -30 dBc but -24 dB referenced to one of the two tones used for testing. That is a figure of merit that I normally use to set drive levels and I consider it the maximum acceptable although, as you point out, there is no spec for most modern equipment and no FCC level other than "must not cause interference outside the signal bandwidth". Modern equipment like the Icom 7300 uses a general specification of -50 dBc for all unwanted emissions and this presumably includes IMD products outside the filter bandpass.

Maybe another way of looking at it: Testing on 80 meters, through a very sharp bandpass filter that limits harmonics and spurs to -60 dBc or better, I set the Drive level to produce +37 dBm on CW. I then put a single tone at -43 dBV into the audio input to get +30 dBm output on SSB. I then increased the tone input in 1 dB increments until I achieved 1 dB of compression. That happened at an audio level of -34 dBV, 9 dB higher than the level to make one watt, and the RF output with that input was +38 dBm. An increase of 9 dB of audio produced an increase of 8 dB in RF output; 1 dB of compression.

I then added a second tone at the same level and measured the difference between one of the tones and the first adjacent product: -15 dB. Opposite sideband products were less than 30 dB down from the primary tone level.

Operation of my radio at the 1 dB compression point results in unacceptable (to me) IMD as well as unacceptable (to everyone) splatter in the opposite sideband and outside the filter sideband on the desired sideband. I could not achieve my desire for -24 dB for the first IMD product with any more than -41 dBV of audio drive which produced an RF output of 1.6 watts.

WA8TOD

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HI,

Here is a picture of my Nano a Nano ISP programming setup. I used the ISP headers with the pins connected one to one, except for the orange wire connected to pin 10 on the Nano programmed as an ISP to reset on the Nano being programmed.

The ISP header pins are connected internally to pins 11, 12, and 13. Because the Nano on my uBITX does not have the ISP header installed, I described the actual pins used rather than the ISP header pins. The brown wire from reset on the ISP programmer Nano to +5V is the (use with caution) direct short disable reset fix.

Be advised on some boards (Uno vs Nano) pin 1 of the ISP header is rotated by 180 degrees. So double check if you use the ISP headers.?



Tom, wb6b

I wasn't having that problem until I installed the AGC board.? Then, when it happened, I soldered a 10nF ceramic capacitor across the audio pot from high side to ground.? The feedback went away, but I noticed the audio has less high response.
Dan, W2DLC

Glad you're back Gordon.

Bet of luck with your recovery.

73
Dennis W7DRW

"brown lead to the center"