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Hi all I am intending to use vfo as a stand alone.How do I disable output from vfo
when I go to recieve on a stand alone reciever (HRO) .If I down power it means tuning
it to frequency again etc.Any help appreciated .
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Hi John. That question has come up a few times before. It is on Hans¡¯ list of things to do. I love using the ?VFO on my boat anchor transmitters except for that issue.
Ron
Hi all I am intending to use vfo as a stand alone.How do I disable output from vfo
when I go to recieve on a stand alone reciever (HRO) .If I down power it means tuning
it to frequency again etc.Any help appreciated .
|
Thanks Ronald,I would have thought that facility would be a necessity.I presume it's on the small transceivers .I may try using a relay to deck the signal?
? ? ? ? ? ? ? ? ? ? ? John G4DXY.
On Thursday, 16 December 2021, Ronald Taylor < wa7gil@...> wrote: Hi John. That question has come up a few times before. It is on Hans¡¯ list of things to do. I love using the ?VFO on my boat anchor transmitters except for that issue.
Ron Hi all I am intending to use vfo as a stand alone.How do I disable output from vfo
when I go to recieve on a stand alone reciever (HRO) .If I down power it means tuning
it to frequency again etc.Any help appreciated .
|
John, it's not very convenient to do, but after getting it on frequency for a QSO, I set the tuning resolution to 10 KHz then just tune it off frequency by one click of the knob, up or down, to get it away from the receive frequency. Not a great solution and you have to remember to turn it back to frequency before transmitting... I tried a relay but even with the thing totally disconnected, it still leaks enough signal out of the Si5351 to get back into the receiver. It really?needs to be turned off during receive. Good luck?... 73 ... Ron
Thanks Ronald,I would have thought that facility would be a necessity.I presume it's on the small transceivers .I may try using a relay to deck the signal?
? ? ? ? ? ? ? ? ? ? ? John G4DXY. On Thursday, 16 December 2021, Ronald Taylor < wa7gil@...> wrote: Hi John. That question has come up a few times before. It is on Hans¡¯ list of things to do. I love using the ?VFO on my boat anchor transmitters except for that issue.
Ron Hi all I am intending to use vfo as a stand alone.How do I disable output from vfo
when I go to recieve on a stand alone reciever (HRO) .If I down power it means tuning
it to frequency again etc.Any help appreciated .
|
Hi Ron ? ? ? ? ? ?I have had an idea ,maybe use the if offset facility and feed into a mixer using an xtal to bring the freq back to where it should be ,and switch the xtal osc off so no output from the mixer .Any bleed through would be Mhz away depending on xtal freq
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? John G4DXY
On Thu, 16 Dec 2021 at 16:17, Ronald Taylor < wa7gil@...> wrote: John, it's not very convenient to do, but after getting it on frequency for a QSO, I set the tuning resolution to 10 KHz then just tune it off frequency by one click of the knob, up or down, to get it away from the receive frequency. Not a great solution and you have to remember to turn it back to frequency before transmitting... I tried a relay but even with the thing totally disconnected, it still leaks enough signal out of the Si5351 to get back into the receiver. It really?needs to be turned off during receive. Good luck?... 73 ... Ron
Thanks Ronald,I would have thought that facility would be a necessity.I presume it's on the small transceivers .I may try using a relay to deck the signal?
? ? ? ? ? ? ? ? ? ? ? John G4DXY. On Thursday, 16 December 2021, Ronald Taylor < wa7gil@...> wrote: Hi John. That question has come up a few times before. It is on Hans¡¯ list of things to do. I love using the ?VFO on my boat anchor transmitters except for that issue.
Ron Hi all I am intending to use vfo as a stand alone.How do I disable output from vfo
when I go to recieve on a stand alone reciever (HRO) .If I down power it means tuning
it to frequency again etc.Any help appreciated .
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Yes John. I think that would do it. Good idea. That should get you by until the software upgrade comes along.?
73¡ Ron
Hi Ron ? ? ? ? ? ?I have had an idea ,maybe use the if offset facility and feed into a mixer using an xtal to bring the freq back to where it should be ,and switch the xtal osc off so no output from the mixer .Any bleed through would be Mhz away depending on xtal freq
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? John G4DXY
On Thu, 16 Dec 2021 at 16:17, Ronald Taylor < wa7gil@...> wrote: John, it's not very convenient to do, but after getting it on frequency for a QSO, I set the tuning resolution to 10 KHz then just tune it off frequency by one click of the knob, up or down, to get it away from the receive frequency. Not a great solution and you have to remember to turn it back to frequency before transmitting... I tried a relay but even with the thing totally disconnected, it still leaks enough signal out of the Si5351 to get back into the receiver. It really?needs to be turned off during receive. Good luck?... 73 ... Ron
Thanks Ronald,I would have thought that facility would be a necessity.I presume it's on the small transceivers .I may try using a relay to deck the signal?
? ? ? ? ? ? ? ? ? ? ? John G4DXY. On Thursday, 16 December 2021, Ronald Taylor < wa7gil@...> wrote: Hi John. That question has come up a few times before. It is on Hans¡¯ list of things to do. I love using the ?VFO on my boat anchor transmitters except for that issue.
Ron Hi all I am intending to use vfo as a stand alone.How do I disable output from vfo
when I go to recieve on a stand alone reciever (HRO) .If I down power it means tuning
it to frequency again etc.Any help appreciated .
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Another idea: Use a 74AC74 or similar flipflop to divide the VFO frequency by 2 or 4. Then use the multipler setting in the VFO firmware to make the display show the divided frequency. Gate the VFO->flipflop clock to get rid of the Fvfo/2 or Fvfo/4 output signal or simply pull the flip-flop's /reset pin low to stop the toggling.
73 SM6LKM
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,maybe use the if offset facility and feed into a mixer using an xtal to bring the freq back to where it should be ,and switch the xtal osc off so no output from the mixer
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Are you planning to use this for CW only?? Or other modes, too?? Do you plan to run the VFO straight into the antenna, or will there be some kind of amplifier or buffer?
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It's to use on a valve? AM transmitter on topband 80 and 60 metres
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On Thursday, 16 December 2021, Jim Allyn - N7JA < jim@...> wrote: Are you planning to use this for CW only?? Or other modes, too?? Do you plan to run the VFO straight into the antenna, or will there be some kind of amplifier or buffer?
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Get better isolation of the VFO by putting it in a metal box.? Cut the output of the VFO by using a logic AND gate,? analog switches, or a series FET switch and a? shunt FET switch to greatly reduce the level.? Control the switches on VFO output with the transmitter PTT line.? Send the signal from the VFO to the xmtr over a coax cable.? Use a microcontroller or whatever to remember what frequency it was on and reprogram the VFO upon pressing PTT button.? There are probably other ways you could do it, this is just what immediately comes to mind.
How strong is the signal getting into the receiver, and under what conditions?? Barely detectable, or way over S9?? VFO board just laying on the table next to the receiver, or in a box with coaxial output and filters on all the power and control lines?
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Hi Jim ,your suggestions whilst welcome? using a microcontroller to remember what frequency it was on is too complicated for me .I think that the lack of a facility to be able to mute the output or switch off the vfo and remember it's set frequency is a serious flaw and to describe it as a vfo is incorrect as it is.Its really a just a signal generator .It works well to generate frequencies and is really only suitable for a receiver or signal generator as it stands.
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?John G4DXY
On Saturday, 18 December 2021, Jim Allyn - N7JA < jim@...> wrote: Get better isolation of the VFO by putting it in a metal box.? Cut the output of the VFO by using a logic AND gate,? analog switches, or a series FET switch and a? shunt FET switch to greatly reduce the level.? Control the switches on VFO output with the transmitter PTT line.? Send the signal from the VFO to the xmtr over a coax cable.? Use a microcontroller or whatever to remember what frequency it was on and reprogram the VFO upon pressing PTT button.? There are probably other ways you could do it, this is just what immediately comes to mind.
How strong is the signal getting into the receiver, and under what conditions?? Barely detectable, or way over S9?? VFO board just laying on the table next to the receiver, or in a box with coaxial output and filters on all the power and control lines?
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the lack of a facility to be able to mute the output or switch off the vfo and remember it's set frequency is a serious flaw ?John, You may think so but not many rigs turn off the VFO or even change its frequency for TX. Maybe I've missed it but I do not remember having seen that as a feature of VFO designs, which ones do? I expect Hans will sometime provide some facility as a few have asked him for it. 73 Alan G4ZFQ
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The issue does not arise with 'modern' rigs where the vfo is one part of a mixer system, and other elements of that are turned on only on tx. 'Back in the day' where the vfo was directly on, or a sub multiple of, the tx frequency it was common practice in simple designs? to mute the vfo in receive mode (not good for stability!) and to be able turn it on briefly in receive mode when a 'netting' signal was required. This arrangement would still be useful when using the QRP Labs VFO as a basis for a 'vintage' AM/CW TX.
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-------- Original message -------- From: Alan G4ZFQ <alan4alan@...> Date: 18/12/2021 08:58 (GMT+00:00) To: [email protected] Subject: Re: [QRPLabs] how to disable output when going from tx to recieve > the lack of a facility to be able to mute the output or switch off > the vfo and remember it's set frequency is a serious flaw ?John, You may think so but not many rigs turn off the VFO or even change its frequency for TX. Maybe I've missed it but I do not remember having seen that as a feature of VFO designs, which ones do? I expect Hans will sometime provide some facility as a few have asked him for it. 73 Alan G4ZFQ
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On 18/12/2021 11:11, Terry Hart G3VFO via groups.io wrote: The issue does not arise with 'modern' rigs where the vfo is one part of a mixer system, and other elements of that are turned on only on tx. 'Back in the day' where the vfo was Terry, Your call had not registered with me, you are obviously a VFO expert:-) I've been a home constructor for a long while but have not been aware of such designs. The QCX and other of Hans kits do use a VFO on the working frequency but do not need to mute.. 73 Alan G4ZFQ
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Not an expert, Alan, just my incredible old age....!
Incidentally, the problem does not arise with direct conversion transceivers as the LO/VFO is by definition always zero beat with itself. It can be an issue when using a separate receiver (such as the HRO), where it can cause interference to the wanted signal or desensitisation.
Have a great Christmas, and stay safe,
Terry
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-----Original Message----- From: [email protected] < [email protected]> On Behalf Of Alan G4ZFQ Sent: 18 December 2021 14:18 To: [email protected]Subject: Re: [QRPLabs] how to disable output when going from tx to recieve On 18/12/2021 11:11, Terry Hart G3VFO via groups.io wrote: The issue does not arise with 'modern' rigs where the vfo is one part
of a mixer system, and other elements of that are turned on only on tx.
'Back in the day' where the vfo was Terry, Your call had not registered with me, you are obviously a VFO expert:-) I've been a home constructor for a long while but have not been aware of such designs. The QCX and other of Hans kits do use a VFO on the working frequency but do not need to mute.. 73 Alan G4ZFQ
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On Sat, Dec 18, 2021 at 12:31 AM, john spendlove wrote:
Hi Jim ,your suggestions whilst welcome? using a microcontroller to remember what frequency it was on is too complicated for me
Then don't do it that way, use one of the other suggestions. It would probably be helpful to those who might want to assist in solving this problem is you would answer these questions: **How strong is the signal getting into the receiver, and under what conditions?? Barely detectable, or way over S9?? VFO board just laying on the table next to the receiver, or in a box with coaxial output and filters on all the power and control lines?**
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The signal is S9 ,old style tx uses vfo on the tx Freq, using mixing in a dBm seems best way to go ,I have no problem with the synth it works well.However as it stands it's not suitable without a means of 1,retaining its Freq when switched off or 2 being able to mute its output unless using mixing techniques etc I was surprised it didn't have those facilities .Many old? transmitters (my era) didn't use mixing techniques and only used on Freq vfo or multiplied it to the band required.I had decided to replace the existing vackar vfo in the tx with a synth .I still use 6AG7 ,807,s 813,s etc.
? ? ? ? ? ? ? ? ? ? ? ? ? ? John G4DXY
On Saturday, 18 December 2021, Jim Allyn - N7JA < jim@...> wrote: On Sat, Dec 18, 2021 at 12:31 AM, john spendlove wrote:
Hi Jim ,your suggestions whilst welcome? using a microcontroller to remember what frequency it was on is too complicated for me
Then don't do it that way, use one of the other suggestions.
It would probably be helpful to those who might want to assist in solving this problem is you would answer these questions:
**How strong is the signal getting into the receiver, and under what conditions?? Barely detectable, or way over S9?? VFO board just laying on the table next to the receiver, or in a box with coaxial output and filters on all the power and control lines?**
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Hi Folks, The issue does not arise with 'modern' rigs where the vfo is one part of a mixer system, and other elements of that are turned on only on tx. 'Back in the day' where the vfo was directly on, or a sub multiple of, the tx frequency it was common practice in simple designs? to mute the vfo in receive mode (not good for stability!) and to be able turn it on briefly in receive mode when a 'netting' signal was required. This arrangement would still be useful when using the QRP Labs VFO as a basis for a 'vintage' AM/CW TX. Terry, G3VFO ? ? ? ?
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From: [email protected] <[email protected]> On Behalf Of Jim Allyn - N7JA
Sent: 18 December 2021 00:10
To: [email protected]
Subject: Re: [QRPLabs] how to disable output when going from tx to recieve? Get better isolation of the VFO by putting it in a metal box.? Cut the output of the VFO by using a logic AND gate,? analog switches, or a series FET switch and a? shunt FET switch to greatly reduce the level.? Control the switches on VFO output with the transmitter PTT line.? Send the signal from the VFO to the xmtr over a coax cable.? Use a microcontroller or whatever to remember what frequency it was on and reprogram the VFO upon pressing PTT button.? There are probably other ways you could do it, this is just what immediately comes to mind.
How strong is the signal getting into the receiver, and under what conditions?? Barely detectable, or way over S9?? VFO board just laying on the table next to the receiver, or in a box with coaxial output and filters on all the power and control lines?
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Thanks all for replies ,after a good search on the net ,several sketches have been found to use with the Arduino which have the facilities I am looking for.I need to evaluate them.One uses an ad9850 rather than the SI chip by an American ham AD7 something which may be a good guide to alter to the SI chip .That one remembers the last Freq used if it's been used for a few secs.As I have previously said the requirements are for using the synth on an old fashioned tx were the vfo is on the transmit Freq.
? ? ? ? ? ? ? ? ? Thanks all? ? ? ? ? ? ? ? ? ? ?John G4DXY
On Saturday, 18 December 2021, Terry Hart G3VFO via <terry.hart= [email protected]> wrote: Hi Folks, The issue does not arise with 'modern' rigs where the vfo is one part of a mixer system, and other elements of that are turned on only on tx. 'Back in the day' where the vfo was directly on, or a sub multiple of, the tx frequency it was common practice in simple designs? to mute the vfo in receive mode (not good for stability!) and to be able turn it on briefly in receive mode when a 'netting' signal was required. This arrangement would still be useful when using the QRP Labs VFO as a basis for a 'vintage' AM/CW TX. Terry, G3VFO ? ? ? ? ? Get better isolation of the VFO by putting it in a metal box.? Cut the output of the VFO by using a logic AND gate,? analog switches, or a series FET switch and a? shunt FET switch to greatly reduce the level.? Control the switches on VFO output with the transmitter PTT line.? Send the signal from the VFO to the xmtr over a coax cable.? Use a microcontroller or whatever to remember what frequency it was on and reprogram the VFO upon pressing PTT button.? There are probably other ways you could do it, this is just what immediately comes to mind.
How strong is the signal getting into the receiver, and under what conditions?? Barely detectable, or way over S9?? VFO board just laying on the table next to the receiver, or in a box with coaxial output and filters on all the power and control lines?
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Ronald Taylor
Jim Allyn - N7JA