Hello everyone

I was finally able to get my mast up to construct a 40m EFHW. I have a number of questions about the antenna as it relates to the Mini, but I'll post that in another thread. My question is to those who use both the Nano VNA and the QRPoMeter. 

When I calibrate the Nano VNA range to 7.025 to 7.120, I'm seeing an SWR of about 1.75:1 in my shack more or less across the range. When I hook up the QRPoMeter and run a test, it bounces back and forth from about 4 to almost 6:1. I was very careful during the calibration process of the QRPoMeter, but I feel like I must be missing something or there is an issue with the QRPoMeter itself. 

I've seen one thread where the QRPoMeter was a little higher reading than other meters, but this seems a LOT higher. 

As I've mentioned before I am still learning CW so I've been using saved phrases with my call sign to conduct my tests. Last night I was seeing spots over 800mi away on the reverse beacon network. 

Thoughts? Thanks Much
Michael

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KD7PTZ

As an additional data point, I tested both the Nano VNA and the QRPoMeter with a 50 Ohm Dummy load. The Nano VNS is showing just a hair over 1:1; the QRPoMeter is showing 2.98. I re calibrated the QRPoMeter, but I"m seeing the same result. If anyone has done any troubleshooting on the QRPoMeter, I'd appreciate any guidance you may have. 

thanks!
Michael

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KD7PTZ

Michael

Maybe it's a connection issue, yes I have experienced some that look connected that aren't. Try using ohmmeter to check to see that connections are made. Where possible touch metal not solder. Especially check the bridge part of the circuit. Something clearly amiss. As for your efhw important to keep feed several feet away from conductors and the ground, but vital to have a way to check its vswr, but you seem to have mastered the nano. 3 to 1 I think half your bridge may not be connected, just a hunch. 

Curt

Thanks Curt

I’m going to need to do some research as I’m not super familiar with the circuits or troubleshooting yet. I was very careful during assembly but clearly there is something amiss. 

Michael
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KD7PTZ

Well start with the knowledge you have. Open the tuner and the build instructions on a screen. Check the construction carefully. Then use an ohmmeter to make continuity checks. Believe something isn't connected right when it isn't working. Others have been there done that. 

Curt

Hi Michael,

Did your QRPoMeter ever work? When I built mine it didn’t work and I was getting inaccurate readings. I found one of the OP amp IC’s was bad but I forget which one. I replaced the OP amp and then it worked perfectly. Also, make sure you have good connections to the paralleled 100ohm SMD resistors. It was slightly difficult to get a good solder connection on those.

Good luck,
‘Gregg W7GRM