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Re: RFI from uBitx TX after AGC and other mods installed
I agree. That would be an excellent fix, Pat. But it shouldn't be occurring. Alan, can you take voltage measurements of Q1? From ground to the base, and from ground to collector when transmitting? It seems that the RF is coming in on the 5 volt power, even though it is well bypassed. Lacking a 'scope, a pair of headphones with one side to ground and the other through a .1uF (or so) blocking capacitor will let you listen to the +5 volt supply. I mean putting the capacitor in series with the headphones. The audio amplifier is disconnected from the pre-amp (which is gated off by the "click" board anyway) and is bypassed to ground by C78 (not shown on the schematic). Which brings up a point: Does the volume control affect it at all? Taking the input to U1 to ground by turning the volume all the way down should eliminate it, I would think. Unless it is coming in on the +12 volt supply (which has nothing to do with the AGC).? -Don
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Re: RFI from uBitx TX after AGC and other mods installed
¿ªÔÆÌåÓýI went down that same path and? ended up picking off receive-only?12v from R52 and putting that through a VR circuit to get 5v for the agc.? This way, you still have cw sidetone during transmit. Just fyi, 73 Pat AA4PG
Pat Griffin
http://www.cahabatechnology.com
From: [email protected] <[email protected]> on behalf of alans77 via Groups.Io <alans77@...>
Sent: Thursday, June 28, 2018 8:33:39 AM To: [email protected] Subject: Re: [BITX20] RFI from uBitx TX after AGC and other mods installed ?
Hi Don: In an effort to eliminate the RF getting back into the audio amp I replaced the TX RF output twisted pair between the uBitx board and my PL259 with coax also switched to coax wrapped 5 turns around a 120-43 core between the volume control and the
AGC board. I still hear my voice loud and clear from the speaker on 80 and 40M. I am going to look for an easy way to to mute the amp or speaker.
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3.5mm Jack Breakout board strip for sale
#ubitx
Someone made a request to order 2 of the jack break out strips I offer for sale via my website and my ISP (or my email client) deleted the message just as I was reading it.
If you would please send it again, I'd be glad to help you. Jim Sheldon, W0EB website http://www.w0eb.com |
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Re: A Breadboard Technique for the uBITX
Jack Purdum
Great minds... Jack, W8TEE
On Thursday, June 28, 2018, 11:53:05 AM EDT, Jon Titus, KZ1G <tituskz1g@...> wrote:
Here's a breadboard technique that might help others.? When my uBITX transceiver kit arrived I had no ideas for a case, so I mounted the board on a piece of plywood and used 1/8-inch clear plastic as front and rear panels for controls and connectors.? I've used this "breadboard" technique for other projects because it lets me rearrange control locations, ensure clearances between components, jacks, heatsinks, etc.? I don't ruin a nice front panel if I need to add an extra pushbutton or switch. After I learned about the W0EB and N5IB RadI2Cino (Rad I2C ino) project, and received a board and parts kit, I needed more room for the replacement board and a larger LCD. The wooden base let me glue a section of plywood on the front (see photo) and move the front panel forward by about 4 cm. I got more space, quickly added an extra pushbutton, and drilled holes to mount the LCD.? Now I can decide of how I want to proceed with a complete package for the transceiver and I'll have a template for holes and cut-outs.? But I might make a few minor changes before then. -- Jon Titus, KZ1G Herriman, UT USA |
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Re: RFI from uBitx TX after AGC and other mods installed
Alan, when you unplug the AGC board, with the audio and +5 volts still attached, does the feedback remain the same? If so, what happens when you remove the +5 volts from the board (still unplugged)? Are you running any other grounds? I think that I see something going to the ground pad next to the +5 volts: What happens if you remove that? Does re-positioning the ClickStop board (moving it temporarily up and toward the front panel) make any difference?
And just being nosey, what is the wire going to near R106? 73, Don |
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Re: Easy, Inexpensive Cooling Fan, Excelway Case
On Wed, Jun 27, 2018 at 06:57 pm, Jack Purdum wrote:
Good idea! See...that's why I'm not an EE kind of guy!Well, I kinda?am an EE kind of guy, kinda, so I should probably fire myself for not thinking about it in the first place! It was easy enough to find a place for +12V on TX, namely pin 3 on U2.? I soldered the positive lead from the fan to that, and now it only comes on during TX. ?? |
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A Breadboard Technique for the uBITX
Jon Titus, KZ1G
Here's a breadboard technique that might help others.? When my uBITX transceiver kit arrived I had no ideas for a case, so I mounted the board on a piece of plywood and used 1/8-inch clear plastic as front and rear panels for controls and connectors.? I've used this "breadboard" technique for other projects because it lets me rearrange control locations, ensure clearances between components, jacks, heatsinks, etc.? I don't ruin a nice front panel if I need to add an extra pushbutton or switch. After I learned about the W0EB and N5IB RadI2Cino (Rad I2C ino) project, and received a board and parts kit, I needed more room for the replacement board and a larger LCD. The wooden base let me glue a section of plywood on the front (see photo) and move the front panel forward by about 4 cm. I got more space, quickly added an extra pushbutton, and drilled holes to mount the LCD.? Now I can decide of how I want to proceed with a complete package for the transceiver and I'll have a template for holes and cut-outs.? But I might make a few minor changes before then.
-- Jon Titus, KZ1G Herriman, UT USA |
Don, ND6T
Jim Sheldon
Arvo W0VRA
Lee