Yes. I read the directions. Radio is stock but reported to be at like 3.5w..
Thank you though.
Meter is packed up for return to store.
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TS DX 350 HDV enroute.. couple questions
- Thread starter CB590
- Start date
Yes. I read the directions. Radio is stock but reported to be at like 3.5w..
Thank you though.
Meter is packed up for return to store.
Perhaps that is best.
Funny though - while I was in the shower after the crazy day I had...
Had a thought about the "construction" - some people whom know of and have used MFJ in the past have blatantly called it Mighty Fine - and I'll leave the rest open for now...
Why did that stick with me? Because of some meters and pots I've had to replace in many radios -their "linearity" of scale - the composition itself - when you go full stop - the wiper no longer had contact with the substrate - the actual contact itself - the rivet - makes the pot appear as a dead short (full stop hard over thingy) so that may be how this meter reacts - over scaled. (non-linear sensitivity)
The only way to test that would have been to; reduce the control to have it's mark like 90 degree right - not full set. (where the pots wiper arm is in composition) Then check the ratio between SWR CAL and SWR - meaning set to SWR to read - if it was like 1.5 or 2 then go to SWR CAL and review that do it go full scale or not even budge from the SWR needle reading (both about the same) - it should show the limitations of the metering circuits' ability of the meters' own VSWR to show PROPER on low power equipment - it's own LINEARITY of scale - tends to prove what others told me about MFJ - see above... the pots' own linearity and required composition resistance - as a construction issue - showed the meters limitations.
That was their biggest gripe was the physical construction and materials used...
And that was on a reactive load, if not the same for a resistive load - shows something else is not properly done for the BANDWIDTH the meter is set up for is not at the proper impedance.
Again... their gripe of a construction issue...
Funny though - while I was in the shower after the crazy day I had...
Had a thought about the "construction" - some people whom know of and have used MFJ in the past have blatantly called it Mighty Fine - and I'll leave the rest open for now...
Why did that stick with me? Because of some meters and pots I've had to replace in many radios -their "linearity" of scale - the composition itself - when you go full stop - the wiper no longer had contact with the substrate - the actual contact itself - the rivet - makes the pot appear as a dead short (full stop hard over thingy) so that may be how this meter reacts - over scaled. (non-linear sensitivity)
The only way to test that would have been to; reduce the control to have it's mark like 90 degree right - not full set. (where the pots wiper arm is in composition) Then check the ratio between SWR CAL and SWR - meaning set to SWR to read - if it was like 1.5 or 2 then go to SWR CAL and review that do it go full scale or not even budge from the SWR needle reading (both about the same) - it should show the limitations of the metering circuits' ability of the meters' own VSWR to show PROPER on low power equipment - it's own LINEARITY of scale - tends to prove what others told me about MFJ - see above... the pots' own linearity and required composition resistance - as a construction issue - showed the meters limitations.
That was their biggest gripe was the physical construction and materials used...
And that was on a reactive load, if not the same for a resistive load - shows something else is not properly done for the BANDWIDTH the meter is set up for is not at the proper impedance.
Again... their gripe of a construction issue...
1.75 on AM and wide open on SSB for that radio and amp combo should work just fine.
I find this odd.
The MFJ model 870 (1.6-60 MHz) requires a minimum of 3 watts for SWR measurement while the model 872 (1.6-200 MHz) requires only 1 watt.
How do the max numbers compare? a change may have been made to accommodate hi power HF rigs.
seems to be a lot of confusion in this thread, and with so much information, that is bound to happen.
i am going to lay out a test for you. do the tests the way i say, and post the results.
first, i wonder if you are using that MFJ870 correctly.
here is what each switch position will do:
FWD- displays the watts coming out of the device connected to the meter. (higher is better)
REV- displays the watts coming back to the device connected to the meter. (lower is better)
SWR SET- use this setting to calibrate the meter for checking SWR. (remember this doesnt actually tune anything)
SWR- after calibrating the meter, switch to this position, key the mic, and read SWR.
so, when you want to see the watts ouput, use FWD.
when you want to check your SWR, use SWR SET and SWR.
connect things like this: radio---- Astatic SWR meter---- TSamplifier------ MFJ meter----- antenna.
remember that when using an amplifier, you actually have two different SWR's to measure.
the SWR between the radio and the input of the amp, and the SWR between the output of the amp and the antenna.
so, put radio in AM mode, channel 20, mic gain all the way down. amplifier OFF.
set MFJ meter to SWR SET, key the mic, and calibrate the MFJ meter (dont worry about the astatic meter yet).
set MFJ meter to SWR, key mic and note SWR reading.
post that reading here.
now switch the MFJ meter to the FWD position. key the mic. note the wattage output. this is your radio's deadkey. post this reading here.
as long as the SWR reading was 2 or less, you can turn on the amp now. dial a watt off, and all buttons out.
now, set the Astatic meter to CALIBRATE postion. with amp ON, key the mic, and calibrate the Astatic meter.
unkey the mic and switch the astatic meter to the SWR position.
key the mic and note this reading. should be 2 or less.
post that reading here.
now, with amp still ON, set MFJ meter to SWR SET position. key the mic and calibrate the MFJ meter. unkey the mic.
switch MFJ meter to SWR position. key the mic and note the SWR reading.
should be less than 2. post that reading here.
now switch the MFJ meter to the FWD position. key the mic and note the wattage output reading. post that reading here.
turn the mic gain on the radio up all the way, push the orange button on the MFJ meter in so you are reading PEP watts.
key the mic and say a steady "ahhhhh" into it.
note modulated wattage reading on MFJ meter and post that here.
good luck on your tests, i think you might not have as many problems as you think you do.
LC
i am going to lay out a test for you. do the tests the way i say, and post the results.
first, i wonder if you are using that MFJ870 correctly.
here is what each switch position will do:
FWD- displays the watts coming out of the device connected to the meter. (higher is better)
REV- displays the watts coming back to the device connected to the meter. (lower is better)
SWR SET- use this setting to calibrate the meter for checking SWR. (remember this doesnt actually tune anything)
SWR- after calibrating the meter, switch to this position, key the mic, and read SWR.
so, when you want to see the watts ouput, use FWD.
when you want to check your SWR, use SWR SET and SWR.
connect things like this: radio---- Astatic SWR meter---- TSamplifier------ MFJ meter----- antenna.
remember that when using an amplifier, you actually have two different SWR's to measure.
the SWR between the radio and the input of the amp, and the SWR between the output of the amp and the antenna.
so, put radio in AM mode, channel 20, mic gain all the way down. amplifier OFF.
set MFJ meter to SWR SET, key the mic, and calibrate the MFJ meter (dont worry about the astatic meter yet).
set MFJ meter to SWR, key mic and note SWR reading.
post that reading here.
now switch the MFJ meter to the FWD position. key the mic. note the wattage output. this is your radio's deadkey. post this reading here.
as long as the SWR reading was 2 or less, you can turn on the amp now. dial a watt off, and all buttons out.
now, set the Astatic meter to CALIBRATE postion. with amp ON, key the mic, and calibrate the Astatic meter.
unkey the mic and switch the astatic meter to the SWR position.
key the mic and note this reading. should be 2 or less.
post that reading here.
now, with amp still ON, set MFJ meter to SWR SET position. key the mic and calibrate the MFJ meter. unkey the mic.
switch MFJ meter to SWR position. key the mic and note the SWR reading.
should be less than 2. post that reading here.
now switch the MFJ meter to the FWD position. key the mic and note the wattage output reading. post that reading here.
turn the mic gain on the radio up all the way, push the orange button on the MFJ meter in so you are reading PEP watts.
key the mic and say a steady "ahhhhh" into it.
note modulated wattage reading on MFJ meter and post that here.
good luck on your tests, i think you might not have as many problems as you think you do.
LC
Ah! You are correct, sir!
Model 870 - 3000 watts
Model 872 - 2000 watts
That likely explains it. Thanks!
While it was hooked up and would not set SWR correctly.. I did try reading power, but every setting came up low.
Like the DK on avg was low, the PEP was low.. Amp on read low dk. Amp swing was low..
I'm convinced the meter is bad, especially since I can't even set a simple SWR cal to get it.. this isn't my first meter it's like my 4th over the years.
I have an MFJ941e I would try and use in bypass, but that has something in the circuit that bypass isn't really bypass..
Will wait abit and order another meter next month, maybe a better one.
For now the 1.2 swr on Astatic looks fine to me. Also the radios built in one says same readings. 1-1.2..
Thank you all for the help.
I also read someplace in all these pages that you talk about setting side band dead key. There is no dead key in side band. Also what makes you think the astatic is correct? What if the mfj is correct and the astatic is off. LoL Kust a thought.
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Min.Power for SWR set...is 3 watts(per manual)...accuracy of meter per normal +/- 10% same as 90% of meters sold...I would believe MFJ over the Astatic or radio any day...just me though
GL
All the Best
Gary
GL
All the Best
Gary
If I was worried about the SWR I would just get an antenna analyzer.. That is what I did.
Why doesn't the MFJ set??
I'm supposedly at 3+ w with stock radio.
Also the radio has built in SWR meter and thus far has proved accurate in my truck for over a year and also matches the Astatic readings within a .
Also antenna is new A99 that is tuned from factory and I only moved a hair hence the 1.2 I'm getting probably.
I get 1-1 and 1-1.2 across band with out anything inline.. and then with Astatic only inline the same..
Supposedly? Is it possible it's slightly under 3 watts? That would explain a lot.
Most of the straws have been grasped. Saw that one hanging and thought I'd grab it.
Hope you get it all sorted out soon and on the air without worries.
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