View Full Version : MFJ 941 instructions

07-18-2007, 01:08 AM
I picked up an old MFJ 941 Versa tuner II at a hamfest, but forgot to ask the fellow how to use it.

This is the original model of the 941 series -- no letters behind the model number.

Anyone know how to use this. I can't seem to figure out how read the SWR. The labeling on the front plate says "SWR/PWR". But it appears to have no switch to move between those functions.

This unit is also lacking a switch to move between set and read. (form the factory that way, the later models 941B - E have a switch to go between set and read).

07-18-2007, 01:33 AM
IIRC, there isn't much difference in the basic operation between the original 941 and the later models. the 941E instructions are available on-line in the form of a PDF file at:http://www.mfjenterprises.com/man/pdf/MFJ-941E.pdf.

The meter on the 941 series is a cross-needle meter. One needle indicates forward power and the other reflected. You read the VSWR off the scale under where the two needles cross.

It should be noted that the accuracy of the forward power reading depends upon the load into which the meter is terminated. It is only accurate when terminated in a 50-Ohm ±JØ (resistive) load like a test or dummy load.



07-18-2007, 06:10 AM
The 941C (and earlier) have only a single needle meter. The meter looks just like that of a typical Monimatch SWR meter.

I have a copy of a copy of the 941C manual. Don't think another trip through the copier will result in a legible version, though.

07-18-2007, 11:27 AM

Those guys at MFJ were pretty sneaky and did a really good job of hiding the fwd/ref switch. Try pulling on the swr/pwr knob and all good things will happen! http://www.qrz.com/iB_html/non-cgi/emoticons/tounge.gif . Nice little tuner and will give you good service as long as you don't try to run a KW through it!

07-18-2007, 12:17 PM
WRV: Bingo: and thank you very very much.

The unit works like a charm and is now part of my emergency "go kit". I got tired of disconnecting the MFJ941D in my shack everytime I wanted to set up portable.

I am amazed at what these little units will do. I had the borrow of one when I first got into Ham radio and that one worked great. But, I had forgotten that one little thing about the knob going in and out.

This one turned out extremely clean inside. Not one spot due to arcing, no dust, no cobwebs, all parts and connections bright and shinney. Someone had replace the diodes in the meter, but did an extremely professional job.

Again, thanks.

ad: dxeng