#109910

Mario,

That scope (like most) usually comes with special little probe tips to plug them in to a BNC/TNC connector. It looks funny because it has no outside latch ring - it connects to the INSIDE of the shield.

I'd wondered what that thing did. Fitted one to a probe and plugged it into a T-connector that I just received and I was good to go! Thanks for the tip! (no pun intended ;-))

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To all,

On a related note, for measuring RF (as opposed to, say, clock signals and square waves going to QDX BS-170 gates), which is the best way to go for the probes - DC-coupled or AC-coupled? On my Tek 465B, I went with DC-coupled but, A, I wasn't working with RF and, B, admittedly, the default for the manual was DC-coupled IIRC and since it worked for my needs then...

Regards,

Charles Johnson
KF4AYT

Dave Morris

#109911

I was able to obtain a Mirage MP1 which was checked against a accurate station monitor. From 2.5 watts to 1000 watts it was dead on, the swr was slightly off, very slightly. This is not the current version of this meter but it measures power in three ranges the smallest being 25 watts. It measures peak and average power and swr. This type of meter seems a good solution for the average person, low cost and reasonable accuracy.?

#109966

“I was able to obtain a Mirage MP1 which was checked against an?accurate station monitor. “

Dave Morris that looks a good instrument ?I expect you have the manual but just in case (and because it could be of wider interest to others):

The circuit info is there, and uses “established methods” quite frequently recreated in homebrew form too (with calibration and meter scale issues that not everyone would relish) ?
I think that an AD8307 style power meter (very simple to build or buy) fed by the fwd and rev outputs of an MP1 style coupler (again homebrew able without great difficulty) would greatly ease the meter scale and calibration issues by the way. ?

Again, the MP1 looks to me to be a well made and attractive power & swr meter, thanks for your posting ?Dave ?

73
Rod
G0VKX

Dave Morris 12:43am?I?was able to obtain a Mirage MP1 which was checked against a accurate station monitor.?

#110521

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Give a man a wattmeter, and he'll know down to the milliwatt how much power he's running.

Give him two, and he'll never know how much power he's running...

(with apologies to the time-honored saw about watches)

73,

-- Dave, N8SBE

Show quoted text

On 2023-09-12 07:07, Bruce Akhurst wrote:

On Tue, Sep 12, 2023 at 02:35 AM, Chris wrote:

Obviously totally useless.

Chris, G5CTH

I'm sure its useful to you so be happy.

FWIW? ?

A 1 : 1:05 SWR implies a? voltage reading across '50 ohms' that's 5% different to nominal/expectation for that power level.? That 5% measurement error becomes 5% squared (10.2%) as you move to reading power.? ?Add your scope error and your power calculation can easily be 15 to 20% out unless you have a way to calibrate your entire measurement system individually.

This would not work at all in a professional environment but in amateur use of course you can decide what's good enough for you.? ?

_._,_._,_

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Best ways to measure output power w/ an o'scope and access ground

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