R1 Setting
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Mornin' Marty: The buffered output from the VFO was added by Dennis for use with older tube-type (valve-type for our European friends)?transmitters?if they wanted to use it elsewhere. I would just pay attention to the heat on the output transistor over time as that gets pretty hot when pushed. We've already mentioned that running with a typical 13.8V can easily brick the power transistor. How much power do you get out when the supply voltage is 12V and the VFO is around 2V? Those are the figures I tend to use and I get about 2W out. Jack, W8TEE From: "Bo Barry bobarr@... [SoftwareControlledHamRadio]" To: SoftwareControlledHamRadio@... Sent: Sunday, August 28, 2016 12:37 AM Subject: Re: [SoftwareControlledHamRadio] R1 Setting Anxious to find the answer.? A recent post said it should be small (forgot value),? but I've found that max power output is when it's cranked up max to 4vp-p.
On Aug 27, 2016 10:41 PM, "Marty Boroff m_boroff@... [SoftwareControlledHamRadio]" <SoftwareControlledHamRadio@...> wrote: > > ? > > Someone very kindly provided step by step instructions for calibrating the 49'er VFO which I followed faithfully when I completed my VFO kit. I lowered the peak to peak voltage as low as I could when I hooked the VFO up to the antenna of my SDR and I was able to adjust the output dead on across the entire 40M band. > > My question is what voltage should I raise it to for the 49'er? The examples of the scope shots show 1v peak to peak. > > > Thanks, > > 73, > Marty WD9GYM > > |
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One of the guys on the Users Group has an Xcel spreadsheet that figures the constant for you. Look through the early posts. Jack From: "Marty Boroff m_boroff@... [SoftwareControlledHamRadio]" To: "SoftwareControlledHamRadio@..." Sent: Sunday, August 28, 2016 1:10 PM Subject: Re: [SoftwareControlledHamRadio] R1 Setting Good morning Jack. Thanks for the response. I will add this information to the calibration notes I have. My bench power supply is a 30A supply which has a switch that allows 13.8 V or make it adjustable. I've set it for 12.0V. I haven't yet begun work on the 49'er board. I have been waiting on my radio club build group to call a session. They usually have them on a Sunday afternoon with a pizza dinner. It's been since April since they had a session. Things have changed a bit around here and I can't always get coverage for my xyl so I decided to proceed with the VFO portion. They have a policy that no one leaves without an operating radio from their sessions. It's the 49'er board that I expect I would run into trouble and the area I am looking for their expertise. Also, building the VFO prior to the meeting will let me just concentrate on that area. I think I've spent enough time on Arduino boards/projects anyway. BTW, tweaking my offset took more compiles than I thought it would. Another reason I am glad I did this part at home. I don't know if I used the correct process to tweak it. Like everything in programming there are multiple ways to solve a problem. What I did was take a measurement with your supplied value. It was high so I dropped the value to the next lowest hole number value with all zeroes. Took a reading and added .1 until I passed by the LCD amount on my radio. Then I dropped down .1 and added .01. And repeated these steps until I ended up with 34.360000000000000. 73, Marty WD9GYM |
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Evidently, we are. I do know that Farrukh just started classes and I know that its a busy time. However, like you said, this has been hanging around for a long time and I'm not qualified to answer it. I'll forward this to him to see if he can give us a quick answer, although I thought he did answer it once before, but I can't find it. Jack, W8TEE From: "ab1br@... [SoftwareControlledHamRadio]" To: SoftwareControlledHamRadio@... Sent: Monday, August 29, 2016 1:05 PM Subject: Re: [SoftwareControlledHamRadio] R1 Setting I've posted the NE612 data sheet in the attachments section. ?The pin 6 L.O. input spec is highlighted. The data sheet recommendation for an external LO pin 6 input is 200mVpp to 300mVpp. Indeed, if a crystal were used instead of an external VFO, the input would likely be in the mV range. To me, this is evidence that pin 6 does not want to see an input amplitude in the volt (vs. mV) range. Proper LO input amplitude reduces possibility of input overload causing less effective filtering and strong signal (BC) images.
Jack, are we still waiting for an answer on this communal repetitive question from Farrukh? Cheers. Jim, AB1BR |
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