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Bitx Drift

Rich Dalton All Messages By This Member #19058 When I received the BitX( #33) the drift was pretty bad so I installed a DDS, UNO and a NT7S Si5351 board which works like a champ. Today in prep for a presentation at my club later in the week I disconnected the DDS and re-soldered L4. Only this time I soldered it to the bottom of the board and I think this did help with the drift. It's not completely gone but is a lot better than before.? The addition of a very large tuning knob also helps with the tuning. As always you mileage may very.
Ryan Flowers All Messages By This Member #19063 Thanks for sharing! Can you explain how soldering L4 under the board instead above would help the drift? As for tuning easier, I built a 20:1 gear reduction drive, but you can also get 10 turn pots cheap on ebay, if you don't mind the wait for shipping.? Ryan KC7RYS
k4dsb All Messages By This Member #19069 开云体育 Ive used the 10 turn pots ...I have the hendricks version of the Bitx...with good voltage regulation to the varicap diode via the pot and precision low % caps in the oscillator circuit...after 10 min of warm up time the drift is very low ..maybe a couple hundred hertz over 15 to 20 min or so..hardly a bothersome drift...anyone remember the old external vfos for HF rigs..at that time...drift like the bitx you would of killed for ... Powered by Cricket Wireless "geocrasher@... [BITX20]" wrote: ? Thanks for sharing! Can you explain how soldering L4 under the board instead above would help the drift? As for tuning easier, I built a 20:1 gear reduction drive, but you can also get 10 turn pots cheap on ebay, if you don't mind the wait for shipping.? Ryan KC7RYS
Rich Dalton All Messages By This Member #19072 I'm really not sure. Could be as simple as a bad solder connection in the original? L4 had been pushed around quite a bit during shipping it was 90 degrees twisted. Stay capacitance to the surrounding parts. I do know when it was on top if I got my finger within a 1/2" the frequency would change.?
ohwenzelph All Messages By This Member #19073 Heat rises, the stuff that gets hot are already on the top of the board.
Rich Dalton All Messages By This Member #19074 ?external vfos for HF rigs..at that time I was thinking the same thing. Hams are kinda spoiled with stability right out of the box now days. And if it's not stable enough for 129.00 you can add the,??High stability temperature compensated crystal oscillator.? ?
Todd K7TFC All Messages By This Member #19075 >>Heat rises, the stuff that gets hot are already on the top of the board.<< The cliche that "heat rises" refers only to heated air. Heat in solid materials moves in any direction that is lower in temperature. Heat in radiant form (long and shortwave IR) moves in whatever direction it's pointed. 73, Todd K7TFC
ohwenzelph All Messages By This Member #19076 all true, but i store my toroids in air. when the radio is cookin', i'd bet that a toroid parked in the middle of the top ( i.e. the side with the warm resistors attached and the side where they would radiate from) of that board is warmer than one parked on the bottom side. sounds like a test worthy hypothesis... and, true or not, would that be a factor in VFO stability?? and while i have ordered npo caps, and have considered changing and moving the inductor, currently my indian made bitx and i are at opposite ends of a continent... so, sadly, i can only conjecture at this point. but it would be fun to actually measure and see if it makes any significant difference. i.e. does it really help to move the toroid to the bottom of the board?
Baruch Atta #19085 I have 100 NP0 caps for 1000pF and 150 pf. ?these are surface mount.? I would be happy to send some to anybody to try.? Just send a SASE to me (I am good on QRZ.com).? Note that I had a bit of difficulty with my mod, so your milage may vary. ? 73, Joe W3TTT toggle quoted message Show quoted text On Mon, Dec 12, 2016 at 8:38 PM, ohwenzelph@... [BITX20] <BITX20@...> wrote: ? all true, but i store my toroids in air. when the radio is cookin', i'd bet that a toroid parked in the middle of the top ( i.e. the side with the warm resistors attached and the side where they would radiate from) of that board is warmer than one parked on the bottom side. sounds like a test worthy hypothesis... and, true or not, would that be a factor in VFO stability?? and while i have ordered npo caps, and have considered changing and moving the inductor, currently my indian made bitx and i are at opposite ends of a continent... so, sadly, i can only conjecture at this point. but it would be fun to actually measure and see if it makes any significant difference. i.e. does it really help to move the toroid to the bottom of the board?
ron van doremalen (PA3FAT) All Messages By This Member #19087 开云体育 Would this solve your problems: Working with W5KUB, Tom Medlin, last days to get the Arduin/SI5351 to work. Still needs some work but no more drift. Ron – PA3FAT ? toggle quoted message Show quoted text Van: BITX20@... [mailto:BITX20@...] Verzonden: 13 December, 2016 17:33 Aan: BITX20@... Onderwerp: Re: [BITX20] Re: Bitx Drift ? ? I have 100 NP0 caps for 1000pF and 150 pf. ?these are surface mount.? I would be happy to send some to anybody to try.? Just send a SASE to me (I am good on QRZ.com).? Note that I had a bit of difficulty with my mod, so your milage may vary. ? 73, Joe W3TTT ? On Mon, Dec 12, 2016 at 8:38 PM, ohwenzelph@... [BITX20] <BITX20@...> wrote: ? all true, but i store my toroids in air. when the radio is cookin', i'd bet that a toroid parked in the middle of the top ( i.e. the side with the warm resistors attached and the side where they would radiate from) of that board is warmer than one parked on the bottom side. sounds like a test worthy hypothesis... and, true or not, would that be a factor in VFO stability?? and while i have ordered npo caps, and have considered changing and moving the inductor, currently my indian made bitx and i are at opposite ends of a continent... so, sadly, i can only conjecture at this point. but it would be fun to actually measure and see if it makes any significant difference. i.e. does it really help to move the toroid to the bottom of the board? ?
Ian Gerard All Messages By This Member #19088 Is there a schematic and write up on this VFO anywhere? It sure looks like a neat project. Thanks for posting it. ? Ian ?K3HQL ? On Tuesday, December 13, 2016 10:35 AM, "ron van doremalen ronvandoremalen@... [BITX20]" wrote: ? Would this solve your problems: Working with W5KUB, Tom Medlin, last days to get the Arduin/SI5351 to work. Still needs some work but no more drift. Ron – PA3FAT ? toggle quoted message Show quoted text Van: BITX20@... [mailto:BITX20@...] Verzonden: 13 December, 2016 17:33 Aan: BITX20@... Onderwerp: Re: [BITX20] Re: Bitx Drift ? ? I have 100 NP0 caps for 1000pF and 150 pf. ?these are surface mount.? I would be happy to send some to anybody to try.? Just send a SASE to me (I am good on QRZ.com).? Note that I had a bit of difficulty with my mod, so your milage may vary. ? 73, Joe W3TTT ? On Mon, Dec 12, 2016 at 8:38 PM, ohwenzelph@... [BITX20] <BITX20@...> wrote: ? all true, but i store my toroids in air. when the radio is cookin', i'd bet that a toroid parked in the middle of the top ( i.e. the side with the warm resistors attached and the side where they would radiate from) of that board is warmer than one parked on the bottom side. sounds like a test worthy hypothesis... and, true or not, would that be a factor in VFO stability?? and while i have ordered npo caps, and have considered changing and moving the inductor, currently my indian made bitx and i are at opposite ends of a continent... so, sadly, i can only conjecture at this point. but it would be fun to actually measure and see if it makes any significant difference. i.e. does it really help to move the toroid to the bottom of the board? ?
ron van doremalen (PA3FAT) All Messages By This Member #19091 开云体育 ? On W5KUB (facebook) there is also the sketch. Not sure if attaching to this mail is the way to go. ? Ron – PA3FAT ? toggle quoted message Show quoted text Van: BITX20@... [mailto:BITX20@...] Verzonden: 14 December, 2016 03:37 Aan: BITX20@... Onderwerp: Re: [BITX20] Re: Bitx Drift ? ? Is there a schematic and write up on this VFO anywhere? It sure looks like a neat project. Thanks for posting it. ? Ian ?K3HQL ? ? On Tuesday, December 13, 2016 10:35 AM, "ron van doremalen ronvandoremalen@... [BITX20]" <BITX20@...> wrote: ? ? Would this solve your problems: Working with W5KUB, Tom Medlin, last days to get the Arduin/SI5351 to work. Still needs some work but no more drift. Ron – PA3FAT ? Van: BITX20@... [mailto:BITX20@...] Verzonden: 13 December, 2016 17:33 Aan: BITX20@... Onderwerp: Re: [BITX20] Re: Bitx Drift ? ? I have 100 NP0 caps for 1000pF and 150 pf. ?these are surface mount.? I would be happy to send some to anybody to try.? Just send a SASE to me (I am good on QRZ.com).? Note that I had a bit of difficulty with my mod, so your milage may vary. ? 73, Joe W3TTT ? On Mon, Dec 12, 2016 at 8:38 PM, ohwenzelph@... [BITX20] <BITX20@...> wrote: ? all true, but i store my toroids in air. when the radio is cookin', i'd bet that a toroid parked in the middle of the top ( i.e. the side with the warm resistors attached and the side where they would radiate from) of that board is warmer than one parked on the bottom side. sounds like a test worthy hypothesis... and, true or not, would that be a factor in VFO stability?? and while i have ordered npo caps, and have considered changing and moving the inductor, currently my indian made bitx and i are at opposite ends of a continent... so, sadly, i can only conjecture at this point. but it would be fun to actually measure and see if it makes any significant difference. i.e. does it really help to move the toroid to the bottom of the board? ? ?

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