|
|
|
|
Hi
thank you, a 1k.-resistor did the trick !
73 Gert DG3OQ
|
Re: Not the W8TEE/TFT board we are looking for.....
I found this on an Arduino forum maybe it will help.
You can find all necessary libraries and examples at official OPEN-SMART google disk here's the link for 2.2" :
|
Re: Choosing a toroid for impedance matching from antenna to NE602
Since the very helpful reply I received from Jean-Matthieu about the Le Tenor radio I have been searching for information about the tuned circuit.
I have read that this type of circuit is a double tuned circuit and so have been reading a lot about this. I think I see how they work so am just going to outline my ideas below in case I am missing something:
Initial data:
input impedance (from antenna): 50 ohms
input impedance to NE602 (1500 ohms)
required tuned frequency: 7MHz
toroid used: T50-2
calculations:
start by picking a capacitor: 280pF (chosen as I have seen this value used in several circuits)
inductor needed to resonate a parallel LC circuit at 7MHz: 1.8uH
turns needed on a T50-2 for 1.8uH: 19
calculate primary turns required to match a 50 ohm antenna to this tuned circuit:
I have 50 ohms on the primary, 17 turns on the secondary and need 1500 ohms later on so try these values first so get: 3 turns on primary
Using the values from above for the second transformer I can now say I require 1500 ohms on the primary of the second toroid and need 1500 ohms for the NE602 so I can just do a 1:1 ratio for the turns on the second toroid, so 17 turns each side.
As far as I have seen (at an initial basic level) this seems to be a good start.
(using Jean-Matthieu's windings of 3 on the primary and 25 on the secondary on a T50-2 for both toroids with 50 ohms primary impedance, I calculate a secondary impedance of 3472 ohms. As I need this matched to 1500 on the NE602 I then calculate I need 16 turns on the secondary of the second toroid to make this match when saying I have 3472 ohms on the primary side)
I do have one more question that I have been searching for the answer to - when impedance matching from say 50 ohms into the tuned circuit is it better to go for a higher value for the reflected impedance part, above I have chosen to use 1500 ohms but Jean-Matthieu calculations suggest 3472 ohms?
|
Re: Bitx20a FREE to a good home
sure.? i will pay shipping. Ron KB6K
On Sat, Dec 2, 2017 at 12:38 PM, Joe Piacentini <j.piacentini@...> wrote: Hello,
I built a Hendricks Bitx20A kit a few years ago.? It actually worked for a bit, had one QSO, but I never got it to work consistently.? Oscillation in the PA, and now I may have added a new problem when I accidentally overdrove the mic input.? Several folks in this group gave me good suggestions, but despite all the help I keep ending up frustrated.? So, in the hope that this kit might bring someone pleasure, I offer it free to a good home.? Any takers?
73 Joe P. AB3LD
|
Re: Bitx20a FREE to a good home
Thanks Joe and Michael,
Ed Kelley
828 Althauser St.
Dubuque, IA 52001
PS send me your PayPal email. Thanks
Ed
On 12/2/2017 5:16 PM, Joe Piacentini
wrote:
toggle quoted message
Show quoted text
Ok, update:
?Michael has decided to pass, so Ed looks like you¡¯re next in
line. Just let me know where to send it. ?
|
Re: Bitx20a FREE to a good home
Ok, update: ?Michael has decided to pass, so Ed looks like you¡¯re next in line. Just let me know where to send it. ?
|
Re: Bitx 40 Hardware Questions
First: I take it the empty pads etc have markings? D an VR numbers? If so, they're most likely superseded by? a 'double-diode package. The original diodes were iN4148(equivalent)s and the trimpot was to balance them. The new package is twinned Schottkys (far better low-signal performance), and manufactured on the one lump of silicon and so inherently balanced. The C103 trimmer was provided *for* as an option to adjust for better audio by pulling the BFO's Xtal frequency a little to a better position relative to the edge of the Xtal Filter's slope (they all can vary a little with manufacturing tolerances). Search back in the Group's Message archive for more in-depth explanation, but upshot is, as has been emphasised here often,"It's a work in progress". Note that yours is V3 - there may yet be a V4 - that's up to Farhan VU2ESE, its creator.
This ought to be a 'sticky' on the Group's homepage ... :)
73 de ZL2DEX
|
Re: BITX40- New RaduinoXP (Mega) PCBs are in and tested
Have you worked out
pricing for the Lotsa Clock pcb Mike and how did your DX mail
weighing of the 2 pcb offer go?
Bill, VK7MX
On 1/12/2017 9:54 AM, Michael Hagen
wrote:
toggle quoted message
Show quoted text
The
second order of RaduinoXP PCBs got here Tuesday.
I have built 4 and am really pleased.
There are LOTS of Connectors.
See attached PDFs for pinouts.
Attached are Blurry Photos of bare and completed PCBs, and the
RaduinoX
(Nano) PCBS for size comparison.
Don't look too long, your eyes will cross!
You can email me for more info.
Bare PCBs for XP are $12 (total US) and a special 1 ea. XP and 1
ea. X
for $16.
So you get Both.
I also got "Lotsa Clocks" board tested.? It is stand alone PCB
with the
Big Brother (20 Pin) SI chip.? It has 2? 8 pin outputs for the 8
Clocks
with a ground in between for coax.? Runs on 4 pin I2C connector
from 5
Volts.? Has 3.3V level shift and regulator on board.
73's
Mike, WA6ISP
|
Re: Bitx20a FREE to a good home
Boy that was fast ?. Ok Michael, you asked first so I guess you win. Just let me know where to send it.?
|
Re: Bitx20a FREE to a good home
If you don¡¯t have somebody already, I¡¯m learning a lot about electronics and I would love to have a 20m kit to play around with. Would be fun to fix too.
Thanks, Ben KD2NOU?
I can PayPal you say 20 to cover shipping
Ed W0IC
On 12/2/2017 2:38 PM, Joe Piacentini
wrote:
Hello,
I built a Hendricks Bitx20A kit a few years ago.? It actually
worked for a bit, had one QSO, but I never got it to work
consistently.? Oscillation in the PA, and now I may have added a
new problem when I accidentally overdrove the mic input.? Several
folks in this group gave me good suggestions, but despite all the
help I keep ending up frustrated.? So, in the hope that this kit
might bring someone pleasure, I offer it free to a good home.? Any
takers?
73 Joe P. AB3LD
|
Re: Bitx20a FREE to a good home
I can PayPal you say 20 to cover shipping
Ed W0IC
On 12/2/2017 2:38 PM, Joe Piacentini
wrote:
toggle quoted message
Show quoted text
Hello,
I built a Hendricks Bitx20A kit a few years ago.? It actually
worked for a bit, had one QSO, but I never got it to work
consistently.? Oscillation in the PA, and now I may have added a
new problem when I accidentally overdrove the mic input.? Several
folks in this group gave me good suggestions, but despite all the
help I keep ending up frustrated.? So, in the hope that this kit
might bring someone pleasure, I offer it free to a good home.? Any
takers?
73 Joe P. AB3LD
|
Re: Bitx20a FREE to a good home
I have a Hendricks Bitx17A kit and I would like a 20 to fix
Ed W0OIC
ekelley828 at centurylink.net
On 12/2/2017 2:38 PM, Joe Piacentini
wrote:
toggle quoted message
Show quoted text
Hello,
I built a Hendricks Bitx20A kit a few years ago.? It actually
worked for a bit, had one QSO, but I never got it to work
consistently.? Oscillation in the PA, and now I may have added a
new problem when I accidentally overdrove the mic input.? Several
folks in this group gave me good suggestions, but despite all the
help I keep ending up frustrated.? So, in the hope that this kit
might bring someone pleasure, I offer it free to a good home.? Any
takers?
73 Joe P. AB3LD
|
Re: Bitx20a FREE to a good home
If you haven't had a taker I'll go for it.? ?I have some equipment that I can troubleshoot with.?
73, MichaEl KM4OLT
|
Bitx20a FREE to a good home
Hello,
I built a Hendricks Bitx20A kit a few years ago.? It actually worked for a bit, had one QSO, but I never got it to work consistently.? Oscillation in the PA, and now I may have added a new problem when I accidentally overdrove the mic input.? Several folks in this group gave me good suggestions, but despite all the help I keep ending up frustrated.? So, in the hope that this kit might bring someone pleasure, I offer it free to a good home.? Any takers?
73 Joe P. AB3LD
|
Re: Bitx 40 Hardware Questions
C93, C103, R106 are not stuffed, and are not needed.
The board is stuffed with MMBT3904's, not BC849's. ?I doubt swapping the MMBT3904's out would improve anything.
Haven't heard many complaints about cold solder joints on R's and C's.
Most boards arrive in working condition, just follow the directions at
Of boards that don't work, it's often trouble with the toroids such as broken or shorted or cold solder joints on the wires.
Perhaps the enamel is not scraped off enough, or scraped off too far back to where they short.
Be careful of all the extra flying leads on those connectors, perhaps cover the ends with tape to avoid them shorting to stuff.
Be careful of the IRF510 heatsink, it is at 12v and a flying lead shorting to that will blow your Raduino.
though the wires on all those toroids are sometimes broken or don't have enough enamel scraped off to be soldered down properly or are shorted.
when they arrive or perhaps?
toggle quoted message
Show quoted text
On Sat, Dec 2, 2017 at 11:23 am, James Lawrie wrote:
First question is what are the empty pads a trimmer used for, should I add trimmers to these, and if so what value would they be?
Second question the sm Transistors are?BC849, would it make any difference to swap out the BC849s with better spec RF Transistors?
Third Question I've noticed some solder joints on the caps and resistors that appear cold, haven't tested yet but have others had this issue? it's an easy fix but just curious.
|
Bitx 40 Hardware Questions
Hello,
I have purchased 3 Bitx 40s v3 and I'm totally new to this transceiver so I have a couple of questions about the PCB and the Transistors.
First question is what are the empty pads a trimmer used for, should I add trimmers to these, and if so what value would they be?
Second question the sm Transistors are?BC849, would it make any difference to swap out the BC849s with better spec RF Transistors?
Third Question I've noticed some solder joints on the caps and resistors that appear cold, haven't tested yet but have others had this issue? it's an easy fix but just curious.
Thanks,
Jim
|
Hello Paul:
Well, yes, I used Si5351, since I am following Farhan's instructions as best I can.
Basically, my set corresponds to the idea of Farhan, except in the control, since I am using an Arduino Mega 2560 board and mechanical encoders.
The main difference, apart from the previous one, is that in the design of my PCB I have included the Si5351, so the connections of this IC to the mixers are very short.
In the attached pdf you can see the design.
In my receiver? some birdies appear, but it works acceptably well. In fact, I get clear signals in all the bands (you can see it in the video)
73 Andr¨¦s EB7ME
|
Been a while since anyone asked about a 20a. Take a look at It sounds like you have all you need to intelligently troubleshoot it.
Leonard
|
ekelley
Michael Monteith
James Lawrie
Andr¨¦s Moreno
