Re: Bitx40 SI5351 drive strength
I checked the drive at the DDS input and found it to be 1vpp.
(from internal VCO)
I did this because I plan to add a DDS also and have a few. I have 2 of the N3ZI ver.1 DDS
and 2 homebrew Uno>9850.? I also have 2 of the Si boards.
Any thoughts on which one ??? I think the N3ZI wants 200ohms....no idea on the others.
Trip - KT4WO
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Frequency counter and huff n puff using Pic
I happened to be working on an MKARS80 which is a variant on the BitX.? I realised that this rig uses a Pic 16f818 as a frequency counter with LCD readout and it generates a huff n puff voltage. If you are capable with Pics it may be worth checking out for use with the new board to give a readout and stabilise the vfo. Code and circuit diagram are here ; Rob | | | | | | MKARS80
Transceiver kit The MAKRS80 is a QRP transceiver designed for use
for use on the 80M band, the circuit was developed from the
BITX20
designe... | | | | Preview by Yahoo | | | ?
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Just a reminder to those using the si5351.? Turn OFF unused outputs.? They will default to a frequency and as in my case cause 'sproggies' across the bands. You can check using a scope etc. to check them. Rob G4NQX
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not at all. you will be able to upgrade that as well! just wait a few...
On 18-Dec-2016 10:22 am, " bruce@... [BITX20]" < BITX20@...> wrote:
?
So does this mean the Bitx40 board that just arrived is now out of date? What has been updated, is there an update for existing boards or do I buy another Bitx40?
Bruce VK2RT
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So does this mean the Bitx40 board that just arrived is now out of date? What has been updated, is there an update for existing boards or do I buy another Bitx40?
Bruce VK2RT
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we have been working at an update to the bitx40. i was to give hfsigs the final go yesterday but i have had to stall it due to a family emergency. the new bitx40 will roll out very soon! until then we have suspended the currenyt sales. orders already booker will be shipped. i know that it is a bummer, we were all looking forward to these boards this chirstmas. they will be delayed for a few days.
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Re: Help with Digital VFO install
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From: BITX20@... [mailto:BITX20@...]
Sent: Saturday, December 17, 2016 2:58 PM
To: BITX20@...
Subject: [BITX20] Help with Digital VFO install? ? Here is my hack problem. I have the new BITX40 V3 SMD board and want to use a IK3OIL FLL with it. - I found where to take the output on the BITX board for the INPUT on the IK3OIL FLL. ?Do I put the + side of a 0.047uf cap to the board in series with the connection to the INPUT on the FLL?
- When I install the VC line from the FLL where do I install it on the BITX board ? ?I believe that I have to remove the VFO coil and tuning capacitor in the BITX VFO when I install the FLL VFO. ? Plus do I use a 100K resistor in series with the connection at the BITX board on this VC line?
Thanks and a Merry Christmas to everyoneyou... ?
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Re: Bitx40 review (video)
I too had to get rid of C91 when adding an external VFO.? Details here, in the last couple of paragraphs: ?
On Saturday, December 17, 2016 3:57 PM, "Joel Caulkins caulktel@... [BITX20]" wrote:
?
Peter,
I didn't need to remove C91 on my BitX40 board, only L4 and it works perfect with a Si5351 and a Arduino, however i too was getting harmonics from the Si5351, so I added a LPF between it and the BitX board and now it works great with a much lower noise floor.
Joel KB6QVI
On Dec 17, 2016, at 12:43 PM, parkerp@... [BITX20] < BITX20@...> wrote:
?
Adding a DDS isn't all plain sailing. ?
I got a horrible whine that was coupled into the BitX via the power supply rail. ?I needed to add some caps and big RF choke to provide isolation. That removed about 95% of it so it's hardly noticeable unless the antenna is removed. ?Another choke should fix it completely.?
Also I sometimes hear a lot of carriers from SW broadcast signals when tuning 7 MHz that weren't there when using the free running VFO. My theory is that it's a harmonic of the DDS VFO but I haven't tracked it down yet.?
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Re: Bitx40 review (video)
Haven't tried this but it should be possible to use L4 (taking off a few turns?) as the inductor in the LPF, so not wasting any parts. ?It could even possibly be done on the board, with a capacitor across R93 and more capacitance across C94/C95. The DDS1 socket connection would need to be changed over to the right side of the LPF inductor.?
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Re: Bitx40 review (video)
Peter,
I didn't need to remove C91 on my BitX40 board, only L4 and it works perfect with a Si5351 and a Arduino, however i too was getting harmonics from the Si5351, so I added a LPF between it and the BitX board and now it works great with a much lower noise floor.
Joel KB6QVI
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On Dec 17, 2016, at 12:43 PM, parkerp@... [BITX20] < BITX20@...> wrote:
?
Adding a DDS isn't all plain sailing. ?
I got a horrible whine that was coupled into the BitX via the power supply rail. ?I needed to add some caps and big RF choke to provide isolation. That removed about 95% of it so it's hardly noticeable unless the antenna is removed. ?Another choke should fix it completely.?
Also I sometimes hear a lot of carriers from SW broadcast signals when tuning 7 MHz that weren't there when using the free running VFO. My theory is that it's a harmonic of the DDS VFO but I haven't tracked it down yet.?
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Re: Bitx40 review (video)
Adding a DDS isn't all plain sailing. ?
I got a horrible whine that was coupled into the BitX via the power supply rail. ?I needed to add some caps and big RF choke to provide isolation. That removed about 95% of it so it's hardly noticeable unless the antenna is removed. ?Another choke should fix it completely.?
Also I sometimes hear a lot of carriers from SW broadcast signals when tuning 7 MHz that weren't there when using the free running VFO. My theory is that it's a harmonic of the DDS VFO but I haven't tracked it down yet.?
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Re: Bitx40 review (video)
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Help with Digital VFO install
Here is my hack problem. I have the new BITX40 V3 SMD board and want to use a IK3OIL FLL with it.
I found where to take the output on the BITX board for the INPUT on the IK3OIL FLL. ?Do I put the + side of a 0.047uf cap to the board in series with the connection to the INPUT on the FLL? When I install the VC line from the FLL where do I install it on the BITX board ? ?I believe that I have to remove the VFO coil and tuning capacitor in the BITX VFO when I install the FLL VFO. ? Plus do I use a 100K resistor in series with the connection at the BITX board on this VC line?
Thanks and a Merry Christmas to everyoneyou...
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Re: BitX40 Spectrum Output
Anyone able to offer some advice on this? The screen shots from my spectrum analyzer are in a folder under my call sign W7AMH.
Thanks,
Tom
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Re: Damage to SMT version bitx40 from nearby transmitter
Raj,
Thanks for the clarification, and the opportunity to climb upon the shoulders of those who precede me.
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Thomas,
I would recommend you do both. The diodes may not take the all power from your other antenna.
Yes the two diodes in parallel are connected between pin 12 of k1 and ground. Both diodes should be
connected in opposite polarity. The line marking the cathode of one should go to ground and
the other diode's cathode should got to pin 12 (Rx antenna line). This will limit the voltage to
less than one volt and that wont damage the Rx.
The bulb is useful for preventing the diodes from blowing up by dissipating excess incoming power.
I used to run a 10M packet bbs link and another antenna was for my base HF. When one transmitted
the other rig lamp used to glow.
You can check the power received by connecting a QRP power meter on the 40M antenna and?
the other port of the meter to a dummy load. You will find out? how much power is picked up by the?
40M antenna when you transmit on the main winlink antenna.
I forget a lot too @ 60! The doctor asked to visit again when I start to forget my XYLs name!
Cheers
Raj
vu2zap
At 17/12/2016, you wrote:
??
Raj,
Thank you for the response. You confirm my fear that the danger of damage is real and present.
I am very much a beginner at this sort of work. I have excellent mechanical and soldering skills, but know little of circuit elements beyond what was required for my license.
I believe you have offered two possible ways to mitigate the risk - either the diodes OR the incandescent bulb. Correct?
If I choose the diodes in parallel, I assume one lead of each goes to pin 12 of K1 relay. Does the other lead of each go to ground? Or where? Be gentle please!
If I choose the miniature bulb, does that bulb function as a sacrificial element like a gas discharge arrestor cartridge? Or is it able to absorb and limit the voltage? I can do either, and it seems you are saying the second option is better.
I???m learning as fast as I can!
Thomas W Noel
KF7RSF
On Dec 16, 2016, at 9:07 PM, Raj?vu2zap@...?[BITX20] <BITX20@...?> wrote:
Thomas,
At pin 12 of K1 relay solder 2 4148 diodes in parallel but in opposite polarity. This will limit the receiver from getting high RF voltage.?
Also if you cut the track between K1 pin 12 and K2 pin 14 and insert a 12v 60 or 40 ma miniature incandescent bulb it would be better. This is common protection method in commercial transceivers and amps. This track seems to be on the component side.
cheaper still!
73 Raj vu2zap
At 17/12/2016, you wrote:
??
How likely is this to happen? Bitx40 connected to 40M resonant antenna perpendicular to another antenna with a 100W transceiver running a Winlink gateway.
I fully expect front-end overload and nasty noises, but will the coupling cause actual damage> I would like to leave the bitx40 running but volume minimized to lessen drift during warm-up period.
Currently I leave it running but antenna dis-connected, but it is only a matter to time until my feeble brain forgets.
Thomas W Noel
KF7RSF
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Re: Bitx40 review (video)
Peter, in the video you mention removing a cap in addition to the toroid from the VFO circuit when converting to a DDS VFO. Which cap did you decide to remove (I assume it would be C91)???
73, AL - VE3RRD
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SolderSmoke Podcast 192 is available
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Re: Bitx40 review (video)
Ah yes, I see it now.? Thanks.
On Saturday, December 17, 2016 7:33 AM, "Raj vu2zap@... [BITX20]" wrote:
?
The blue RV1 is the bias set for the IRF. The drive is set by the preset
R136 before the driver transistor.
At 17/12/2016, you wrote:
?
Another nice video Peter.? Thanks.?? In your comment on
the pot in the RF amp stage, I think you made the same mistake that I
did: assuming that that pot was for setting the IRF-510 bias (as was the
case in all earlier BITX circuits).?? But take a look at the
schematic:? The bias is set by a regulator chip (smart move Farhan!)
and that pot just sets the RF level going to the driver (thus allowing
VK3YE to go QRPpppppppppppp from the beach!). 73? Bill
On Saturday, December 17, 2016 1:59
AM, "parkerp@... [BITX20]"
wrote:
?
There's not much in it that most people here won't already know, but a
video review I've just uploaded could still be of interest.
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Re: Pop in speaker on key-up
Tnx for the help. I didn't use the right search terms.
I will dig up some of the older posts, but will prob. just live with it.
Once I have in metal case maybe it will clean up some.
My only issue so far was L3 was broken off the board when it arrived.
Fixed that and up and running!!
Tnx de Trip - KT4WO
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Re: Bitx40 review (video)
The blue RV1 is the bias set for the IRF. The drive is set by the preset
R136 before the driver transistor.
At 17/12/2016, you wrote:
toggle quoted message
Show quoted text
?
Another nice video Peter.? Thanks.?? In your comment on
the pot in the RF amp stage, I think you made the same mistake that I
did: assuming that that pot was for setting the IRF-510 bias (as was the
case in all earlier BITX circuits).?? But take a look at the
schematic:? The bias is set by a regulator chip (smart move Farhan!)
and that pot just sets the RF level going to the driver (thus allowing
VK3YE to go QRPpppppppppppp from the beach!). 73? Bill
On Saturday, December 17, 2016 1:59
AM, "parkerp@... [BITX20]"
wrote:
?
There's not much in it that most people here won't already know, but a
video review I've just uploaded could still be of interest.
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Joel Caulkins/N6ALT
Raj vu2zap