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Sundar, It should be best sound around half. Just check if final audio tr's are too hot! Raj

Glenn, Please try a mod.. Remove first transistor's base bias resistors uBitx = 1K and 2.2K Connect a 39K or 47K resistor from first base to last emitter. The emitter voltage will be around 5-7v. I

Dear Raj, I? added one 100 ohms preset (not trimmer) in between the diode d15 and D16 (after cut the track) the audio is ok and volume is increased. Good result. vu2nsk

Interesting, I had built the uBITX bi-amp stage only, on a small pcb some time ago. I just measured the 2nd and 3rd harmonics as shown below, with -30, -20 and -10dBm input from an HP8640B sig gen and

Which corner frequency for the LPF solution should be used, 50Mhz?

Excellent finding! Adding a low pass filter seems the easiest solution. At which impedance should be designed? 50ohm, 500ohm? Where exactly place it, considering the schematics of ver. 3 and ver. 4. I

I tried EPCOS TDK and it works as well as one marked S+M https://www.ebay.com/itm/480pcs-kit-assorted-chip-inductor-coil-1210-1008-24x20pcs-EPCOS-TDK-MURATA/142968653807 This one has it marked R68K ,

The SMDs I used are marked S+M and yellow in color. Smaller ones did not help. Just do the relay mod for now.. don't use sockets for them. Raj

Mark wrote: When transmitting, the display should show the frequency of the carrier in the case of CW, and should show the frequency of the suppressed carrier in the case of SSB. If your firmware does

What firmware are you running?? Mine seems to be OK on xmit but several hundred Hz off on rcv. I'm thinking it might be the constants used in the firmware for the USB & LSB offsets. They're used by

Thank you 73’s

the 45 mhz if amplifier is distorting and producing a second harmonic at 90 mhz. this mixes with the local oscillator to produce a spur at 90 mhz - local oscillator. here is how it happens : the spur

Roger I got put on moderation by Wicked Witch of the West or perhaps it was the Tin Man.? Bit like being stuck in Mt Eden Gaol for a few weeks without any playthings except the local Tribesmen.. .

Evan It's almost certain the dimming is done by PWM, ie chopping the LED supply.?? Did you try adding some series inductance to the display supply along with your extra capacitors.? vk3pe

A relative and I have both purchased the uBitx boards and upgraded to the CED firmware with a Nextion diplay (he has a 3.5" enhanced and I have a 2.4" enhanced). Both exhibit a tone when the LCD is

Tim....some one has to tell the truth. There much BS talked here.....

This might have been posted before, so forgive me if doubled up, but an interesting web page on how to use Axicom rf type relays. http://www.i1wqrlinkradio.com/antype/ch97/chiave50.htm vk3pe

Watch it Roger, they will ban you from the site and then you won't get to hear about Rev 5 and the 50 percent off coupon that AF is going to give out to disgruntled purchasers of V3 and V4 boards.

I don't agree.....this rig will work to some extent and I have used it for QSOs on 80-40- and 20 metres in CW SSB FT8 and WSPR. But the software calibration to get it working correctly is an

Hi Bill. This is a bare Si5351 board being controlled by an Arduino. This is the environment in which the calibration sketch expects to execute. If I set the correction constant, I get the correct