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troubleshooting the bitx40 receiver
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Excellent!! Todd K7TFC On Dec 25, 2016 11:18 AM, "Ashhar Farhan farhanbox@... [BITX20]" <BITX20@...> wrote:
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Thomas Noel
¿ªÔÆÌåÓýAshhar,In the receive troubleshooting video, what is the unseen end of the red insulated wire connected to? Or nothing? Thomas W Noel KF7RSF
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I second KF7RSF's comment. ? Can you please tell us what the red wire /speaker connection is you are using? It's not clear on the video. Kent? W9WB? On Dec 25, 2016 3:33 PM, "Thomas Noel tnoel@... [BITX20]" <BITX20@...> wrote:
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it is not connected anywhere. it is hanging off the table On 26-Dec-2016 6:03 pm, "Kent Vanderploeg kvanderploeg@... [BITX20]" <BITX20@...> wrote:
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I think we're misunderstanding each other. ? The red wire connects to a speaker.? What does the other end of the speaker connect to? We can't see the wiring in the video, ?so perhaps you're using the speaker circuit on the board to test with?? That's what we're trying to understand.? Kent? W9WB? On Dec 26, 2016 6:36 AM, "Ashhar Farhan farhanbox@... [BITX20]" <BITX20@...> wrote:
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¿ªÔÆÌåÓýKent, I am pretty sure the speaker you see and hear is connected to the speaker connections on the board.?? The red wire Farhan is holding is not connected to anything and Farhan is just using it to inject noise into the board at the various places he describes for troubleshooting.? The other end is as he describes, just dangling off the table. ? 73, Dale? K9NN ? From: BITX20@... [mailto:BITX20@...]
Sent: Monday, December 26, 2016 7:52 AM To: BITX20@... Subject: Re: [BITX20] troubleshooting the bitx40 receiver ? ? I think we're misunderstanding each other. ? The red wire connects to a speaker.? What does the other end of the speaker connect to? We can't see the wiring in the video, ?so perhaps you're using the speaker circuit on the board to test with?? That's what we're trying to understand.? ? Kent? W9WB? ? On Dec 26, 2016 6:36 AM, "Ashhar Farhan farhanbox@... [BITX20]" <BITX20@...> wrote: ? it is not connected anywhere. it is hanging off the table ? On 26-Dec-2016 6:03 pm, "Kent Vanderploeg kvanderploeg@... [BITX20]" <BITX20@...> wrote: ? I second KF7RSF's comment. ? Can you please tell us what the red wire /speaker connection is you are using? It's not clear on the video. ? Kent? W9WB? ? On Dec 25, 2016 3:33 PM, "Thomas Noel tnoel@... [BITX20]" <BITX20@...> wrote: ? Ashhar, ? In the receive troubleshooting video, what is the unseen end of the red insulated wire connected to? Or nothing? ? Thomas W Noel KF7RSF ?
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Dear farahan have u uploaded bitx transmitter troubleshooting? kindly send me link On Monday, December 26, 2016 5:18 AM, "'Dale Hammer' DaleHammer@... [BITX20]" wrote:
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Kent, I am pretty sure the speaker you see and hear is connected to the speaker connections on the board.?? The red wire Farhan is holding is not connected to anything and Farhan is just using it to inject noise into the board at the various places he describes for troubleshooting.? The other end is as he describes, just dangling off the table. ? 73, Dale? K9NN ? From: BITX20@... [mailto:BITX20@...] Sent: Monday, December 26, 2016 7:52 AM To: BITX20@... Subject: Re: [BITX20] troubleshooting the bitx40 receiver ? ? I think we're misunderstanding each other. ? The red wire connects to a speaker.? What does the other end of the speaker connect to? We can't see the wiring in the video, ?so perhaps you're using the speaker circuit on the board to test with?? That's what we're trying to understand.? ? Kent? W9WB? ? On Dec 26, 2016 6:36 AM, "Ashhar Farhan farhanbox@... [BITX20]" <BITX20@...> wrote: ? it is not connected anywhere. it is hanging off the table ? On 26-Dec-2016 6:03 pm, "Kent Vanderploeg kvanderploeg@... [BITX20]" <BITX20@...> wrote: ? I second KF7RSF's comment. ? Can you please tell us what the red wire /speaker connection is you are using? It's not clear on the video. ? Kent? W9WB? ? On Dec 25, 2016 3:33 PM, "Thomas Noel tnoel@... [BITX20]" <BITX20@...> wrote: ? Ashhar, ? In the receive troubleshooting video, what is the unseen end of the red insulated wire connected to? Or nothing? ? Thomas W Noel KF7RSF ?
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On Monday, December 26, 2016 9:47 AM, "vijai george vijaigeorge2005@... [BITX20]" wrote:
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¿ªÔÆÌåÓýKent, The red wire is just a wire acting as a antenna for injecting some signal into the circuit. The speaker is just hooked up to the BitX40 in normal fashion using the onboard audio amplifier. You could use a simple RF generator and a probe to do the same thing. ?Farhan is just using stray RF noise to test the different stages. Joel Caulkins KB6QVI On Dec 26, 2016, at 4:52 AM, Kent Vanderploeg kvanderploeg@... [BITX20] <BITX20@...> wrote:
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kent the other end u can put our finger to inject noise? dont connect speaker to red wire On Monday, December 26, 2016 7:09 AM, "Joel Caulkins caulktel@... [BITX20]" wrote:
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Kent, The red wire is just a wire acting as a antenna for injecting some signal into the circuit. The speaker is just hooked up to the BitX40 in normal fashion using the onboard audio amplifier. You could use a simple RF generator and a probe to do the same thing. ?Farhan is just using stray RF noise to test the different stages. Joel Caulkins KB6QVI On Dec 26, 2016, at 4:52 AM, Kent Vanderploeg kvanderploeg@... [BITX20] <BITX20@...> wrote:
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Thanks for the video.? Testing shows the L2 is definitely bad.? No signal passing to C3.? I've "extracted" the remains of L2 since it was already cracked.? Removing the superglued remains was trickly, but some Super Solvent helped.? I temporarily jumpered the terminals for L2 and I can actually hear SSB signals now.? Before, I could only make out a single, very strong CW signal. ? I did trying calling CQ and throwing out my call to some strong signals, but heard no replies.? Does L2 affect the output signal as well? I can only get the LDG Z-817 tuner to tune if I whistle VERY strongly into the mic.? My FT-817 will tune on SSB at 1W by humming into the mic. ? Kent? W9WB On Mon, Dec 26, 2016 at 9:20 AM, vijai george vijaigeorge2005@... [BITX20] <BITX20@...> wrote:
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L2 is in the signal path for both transmit and receive.
Replacing the 6uH L2 with a piece of wire will mess with the tuning of that filter, and almost certainly reduce the signal that gets transmitted as well as what's received. But the fact that you are getting something to work on both transmit and receive suggests you are most of the way to having a working rig. Jerry, KE7ER |
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While you're waiting for a replacement core, you could replace L2 with an air wound coil, wound on a soda straw or the like. ?Plenty of "single layer air coil calculators" out on the web to determine how many turns to use given the diameter of the form and how many turns per inch you get with the enameled copper wire you have available. ?I'd go for an extra 10% of inductance, or 6.6uH, and then adjust it by spreading the coil out for maximum signal. ?On most enameled wire, you can just heat it good with a good hot soldering iron, burning off the enamel and tinning the leads all in one go. ?If that doesn't work, try extra flux, or scrape the enamel off first.
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The L2 will need 6uh inductance. This will need a fairly large coil. The advantage of the toroids is that they are self shielding. The air core coil is bound to pick up magnetic fields from other coils resulting in out of band signals on reception and instability on transmit. on the other hand, there is nothing to prevent you from using another toroid (including a tap washer) with enough turns to hit 6uh inductance. - f On Tue, Dec 27, 2016 at 4:03 AM, jgaffke@... [BITX20] <BITX20@...> wrote:
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Wouldn't a tap washer become saturated? Or are you suggesting it as a stopgap until the proper toroid can be obtained? Rich KC8MWG On Monday, December 26, 2016 5:44 PM, "Ashhar Farhan farhanbox@... [BITX20]" wrote:
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at the power levels of the band pass filter, there is no fear of the tap washer being saturated. to test this, try microwaving it. - f On Tue, Dec 27, 2016 at 4:28 AM, Richard Knack ihc73scout2@... [BITX20] <BITX20@...> wrote:
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Unfortunately, I doubt Kent has tools to measure inductance, and so has no way to accurately create a 6 uH coil using a tap washer. ?When I hear tap washer, I think of one of those little rubber things you stick in a water faucet to keep it from dripping, is that what you have in mind? ?What size? ?How many turns for 6uH? ?What size wire? ?On the bright side, I doubt rubber would saturate.?
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You're right though, 6uH is not soda straw territory. ?A more reasonable diameter would be a couple centimeters, with 1mm per turn that's around 2 cm long for 6uH. Given no suitable cores, if I were Kent I'd be winding an air coil to get by till a core arrives. ?Even if it was a bit big and did pick up stray fields, it's at least easy to calculate and easy to adjust for maximum signal. ?Good enough to verify the rig works and move on to the next issue, like a suitable enclosure. Though I must concede that Ashhar has way more experience with this sort of thing. Jerry, KE7ER ---In BITX20@..., <farhanbox@...> wrote : at the power levels of the band pass filter, there is no fear of the tap washer being saturated. to test this, try microwaving it. - f
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You're correct, ?I have no way to measure inductance. ? My quick look at making an air inductor showed it would be larger than I'd like to mess with, ?as I have replacement parts en route from FL.? I should have components to wind a proper replacement in a couple of days.? Kent W9WB? On Dec 26, 2016 6:27 PM, "jgaffke@... [BITX20]" <BITX20@...> wrote:
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For discussions of using a tap washer, see the original BITX design; search this group for a lot of answers...
The point of using a plastic washer is that it will provide the self-shielding properties of a toroid. Actually, using powdered iron or ferrite is a means of increasing the inductance so that fewer turns are involved. But any toroid of plastic, or wood or anything else would work. Think copper washers. The only real concern is finding something that will not bite into the insulation of the wire and short it. And, of course, getting the wire ends properly into the circuit. As to finding a suitable 6 uH inductance, tear apart an old FM radio and remove one of the IF transformers; one of the windings of that transformer will almost certainly adjust to about 6 uH, and can be used in the BPF. If you are lucky, your junk box contains a 10 MHz IF transformer. The easiest thing to do with a linear inductance is use a soda straw. It will provide rigidity and will work well. One may have to arrange it on the board for minimum extraneous RF pickup, but we are hacking here, after all. There are references here in the group, in the Minima mailing list, and other places on the internet as to how to do this, e.g., google permeability tuning. john AD5YE ---In BITX20@..., <jgaffke@...> wrote : ... You're right though, 6uH is not soda straw territory. ?A more reasonable diameter would be a couple centimeters, with 1mm per turn that's around 2 cm long for 6uH. [john] True, for a single layer. What about 2 or 3 layers? Given no suitable cores, if I were Kent I'd be winding an air coil to get by till a core arrives. ?Even if it was a bit big and did pick up stray fields, it's at least easy to calculate and easy to adjust for maximum signal. ?Good enough to verify the rig works and move on to the next issue, like a suitable enclosure. Though I must concede that Ashhar has way more experience with this sort of thing. Jerry, KE7ER |
Todd K7TFC
Joel Caulkins/N6ALT
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