Re: QRP SWR meter recommendation? #ubitx

Gordon Gibby <ggibby@...>

Here is an example of one of the little swr indicators  where you just dim the diode

I’ve used that kind of a circuit as well as the two torrid system  others recommended which also works fine but you’ll need an external meter or voltmeter or something. 

On Aug 20, 2018, at 13:14, Bill Cromwell <wrcromwell@...> wrote:

Hi Mike,

The tuner itself does not care how much power you use to 'set' it as long as it isn't *more* than it can handle. It is not impressed if your TX can pin the needle or not. If your uBitx will only drive the meter to half scale in it's "Forward" configuration then set the "Cal" knob full right. Flip the switch to "Reverse" and adjust the tuner for minimum as per usual. If you can get it all the way to zero - well zero is still zero. And less is still less. So what if you can't read that it is 1.25 to 1 if it is 1.25 to 1. A zero in "Reverse" is 1:1 no matter how high the TX didn't drive the needle in "Forward".

I built an SWR bridge that could be pinned with less than two watts (maxed at about 30) and discovered that it doesn't make any difference as described above. What does make a difference is a tuner and SWR bridge built for QRP power levels can be made much smaller and lighter:) Put the tuner and the bridge in the same box together for even more convenience out in the field. Like a scaled down version of your MFJ. If you build it into your uBitx you will forfeit using it with other radios but will be even more convenient when taking the uBitx to the field.

Keep us posted with progress.


Bill  KU8H

On 08/20/2018 11:31 AM, Mike KK7ER wrote:
So far I have been setting the antenna tuner using my Kenwood and then
swapping in the uBITX.  But now we want to take the uBITX on the road.
Problem is that the uBITX does not put out enough power for full
deflection on our MFJ versa tuner II so we cannot get an accurate SWR
reading to tune the antenna.  Does anyone have recommendations for a QRP
SWR meter?  Thanks!

73, Mike KK7ER
(and son KI7ZZS)

bark less - wag more

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