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- เผยแพร่เมื่อ 4 ต.ค. 2024
- Follow the Watt meter thread on EEVBLOG
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RF Power Meters Tested and Compared. Not all Power Meters are equal!
• RF Power Meters Tested...
My homemade in-line Watt meter
• Homemade in-line RF Wa...
![ลองสั่งของจากแอพ temu ถูกจริงหรอ?? ( part : 1/2 ) [โกงไหมครับ ep.89 ] | DOM](http://i.ytimg.com/vi/RTcZSQTiDZw/mqdefault.jpg)
Well… good to know. Thanks for sharing this test and in a such accurate fashion.
Best wishes
Diego
Will there be a disassembly video on this one ? Would be cool to see whats inside and maybe find out why it is so .. off..
I thought about it but the video was already getting long. If I pull it apart, I will add them to the Watt meter thread on EEVBLOG.
I have the MFJ-845 version. The instructions say the backlight will come on while transmitting then turn off after a while after keying off. But, mine is intermittent. I just got it a couple of days ago and was working fine and matching up pretty closely. Then all of a sudden it's showing misreadings of 99:1 SWR and nearly 100% reflection except at 14MHz (20m band) where it fluctuates. I'll be cracking it open to see if something got burnt and to check that shield of the coax.
Also, it is exactly the same. MFJ just got it white labeled and slapped their logo on it. Also, the SO239 connectors are really crappy. You must be careful not to bend the pins. The insulator inside can slide down and expose the top of the pins. I took a plastic straw and made inserts to prevent the insulator from sliding down.
Thanks for the post. Please provide us with some details on the shielding once you have yours apart.
The coax wasn't grounded. I did so. Also I replaced the SO239s with far more superior quality connectors...BUT... It's still not working properly. I checked it against all HF bands and only on 10m (28-29MHz) doest it read SWR correctly. Nonetheless, despite giving pinned 99:1 reading the SWR on the feed line and at the rig remains stable and correct. Does this just need to be recalibrated?
Lol, Joe. Maybe they were hoping it would fall out of the box in shipping so you wouldn't be able to actually test it 😂
You may be right as right after my review, it appears it is no longer available on Amazon.
Great videos Joe
Maybe they are just using say 1N4007 or any silicone diodes that are cheap, i found this in. AT100 ATU,
I changed to the correct ones and it is now reading fine,
Dave 2E0DMB
I may have to pull it apart and have a look.
@@joesmith-je3tq yes do open it, and see what they have messed up,
Dave
The screen on this is almost identical to the MFJ one, which a lot of people have declared to be junk (erratic readings). I wonder if they are from the same factory.
Does look like it. I watched this review of the MJF. th-cam.com/video/OBimdjiK-YA/w-d-xo.html He doesn't check the entire frequency range but his does appear to be far more accurate than mine at 7MHz.
@@joesmith-je3tq It is exactly the same. MFJ just got it white labeled and slapped their logo on it. Also, the SO239 connectors are really crappy. You must be careful not to bend the pins. The insulator inside can slide down and expose the top of the pins. I took a plastic straw and made inserts to prevent the insulator from sliding down.
This feels like a prototype someone would make based off a rough idea for a mass manufactured product but instead of going back to the drawing board they just shipped it
or maybe last minute cheaping out on machining
I enjoyed this, disappointing as it was haha. I have an old Micronta VHF/UHF meter in this style (analog needle meter though) which I need to test against a proper lab power meter. If it’s between a Bird 43 and this joke you checked out, obviously the old 43 is a “Cadillac” of meters, but as you said their precision is really not all that great, particularly compared to lab standard meters.
I wouldn't be too surprised if many of the old time analog Watt meters would not out perform this modern digital one. It's hard to believe it's this bad and they are able to sell them. Maybe it's defective but it's not worth getting a second one to try when I really don't have a use for it.
Until I got an HP RF power meter I always used a carbon comp resistor and a scope when I wanted close RF power measurements. Every other sort of RF power meter I was able to afford was not much better than just guessing. I've had the HP now for 2 years, and of course now that I have one I haven't actually had any need to use it.
I would normally use my spectrum analyzers to measure power. After I bought that old Agilent PNA and upgraded it to 9GHz, I wanted to align it. This was the whole reason to buy that R&S meter. I have not used it since, until now that is.
@@joesmith-je3tq any chance you have video of this process ? Extending Agilent PNA to 9GHz, sounds awesome
@@МаксимТретьяков-в7г Nope but you can read about it here: www.eevblog.com/forum/testgear/agilent-e8357a/
www.eevblog.com/forum/testgear/agilent-e835xa-pna-vna-notes/
I guess you have a calibration issue. There are trimpots inside so it's easy to calibrate this meter. My RS-70 is almost spot-on with respect to power and SWR. But of course not perfect as it's not a 1000 dollar lab instrument.
I posted a photo of it on EEVBLOG. There is a trimmer cap that ties to the center tapped transformer and two trim pots off the two outside legs. As far as aligning the meter, I have not made any attempts. It should have been aligned when shipped.
Great! It seems everything I've bought is a piece of crap after watching these videos. First, the Nano VNA-H4, but too complicated to use. Then the Surecom SW-33, but one video says it's just junk. Finally, a Nissei RS-50 similar to this one, but if the RS-70 is what you're saying it is, then I can assume the same with what I have. Geez, I just want an accurate SWR and power meter without breaking the bank and all the complications!
RS50 should have a completely different coupler. There is no way the one used in the RS-70 would work to 500+MHz, even if it didn't have problems. If you know someone with the equipment, maybe they could test it for you. H4 can't measure power so even if you took the time to learn to use it, its out.
Check the frequency range. MFJ has two versions. One for HF and another for VHF/UHF.
Your USB power bank keeps turning off because of the low load. That's what's making the meter reset.
Very well could be. I did not try another pack or charger. Funny it turns right back on.
Just tried using mine tonight, with my IC-705 on 5 watts and... nothing.
Nothing, so won't even power up. That's pretty bad.
You can get non-inductive (Ayrton-Perry winding) wire power resistors.
Yes, but it's not something you would use for a load. Well, then again, I saw a ham make a video where he was using a home water heater but he was struggling to understand why it would work at some frequencies and not at others...
Why not, Joe? I have tried them as dummy loads for my Ham station, and I have not seen any issues as compared to the big carbon pile resistors I also have. VSWR is very good on the Dale units I have. Maybe I'm missing something?? Thanx for your channel. Always look forward to your torture tests.
@@Homer19521 Did you measure the S-parameters and post that data somewhere? If so, I would like to see your work. If not, start by providing the part number of the device you used and the frequency range you use it at.
@@joesmith-je3tq I don't have a VNA so all my measurements were with a DER5000 (to measure R&L) & the variety of SWR meters I have. I measure 1:1 on 160M (1.850MHz) and 1.6:1 on 6M (53MHz). For this measurement, I used the Icom radio's SWR meter. For a hack like me, that's good enough. Some day I will measure it on my VHF/UHF rig. It maybe an issue there. PN is: Dale NH-100 1% 100W
@@Homer19521 For the mismatch standards, they need to be constant. Normally I am using these for low signal measurements. If you look at the data sheets for the part you show, there is no S-parameter data available. Now, I'm not suggesting you can't use them for a dummy load. Similar to the ham with the hot water heater, they apparently get a decent match at some frequency. Now days, we have these low cost VNAs available for $50. When I made the video for the home made Watt meter, I demonstrated measuring some mismatch loads. These same loads were seen being measured with one of those low cost VNAs when I first received it.
G A R B A G E !!
Ze Germans would say: Wer misst, misst Mist!
Wer viel misst, misst viel Mist ;)
@@tinygriffy After looking at that Gossen Metrawatt DMM, I am not surprised they would say something like this. I want repeatable, accurate measurements. I should be able to go back in a year, repeat the tests and get the same results.
@@joesmith-je3tq For that reason my first multimeter come from Japan.
Chinese junk. Did you expect something else?
Bird 43 meters with proper slugs are typically much better than +/- 5%. They’re built like a tank, very durable, and accurate. They deserve more respect than you’re giving them.
The slugs are for specific frequency segments and power ranges. Each slug is trimmed over the frequency and power range and verified to be within spec, typically much better.
It's not the Watt meter I have disrespect for.
Sounded like the disrespect was directed towards hams, grouping them with CB’ers and calling them “hammies”.
@@R50_J0 There's a reason I no longer have a license.
I’m sorry to hear that.
@@R50_J0 Don't be. It was a good stepping stone to becoming a EE. Advancing the art and such...
I was about to get this toy for infield days but at this point is just a toy for demonstation only at 14Mghz.
Save your hard earned cash.
tried to call you
I want to help me send a program (VI) to the card ADS1262