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Author Topic: Yaesu FT-60, VX-150 output only 4W, not 5W?  (Read 823 times)
KE2KB
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Posts: 633




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« on: October 23, 2017, 03:56:10 PM »

Hi;
I had never checked the output power on either my Yaesu VX-150 or FT-60 until today. To my dismay, I find that neither of the radios actually puts out the full 5W as is specified.
Here is my setup for measuring:

Diamond SX200 watt/swr meter.
Opek DL-60 dummy load
approx 10ft length of RG58 connecting the HT to the meter.
Battery: Yaesu FNB-83 fully charged (shows 8.0V when I check it on the HT)

If I connect a 13.5VDC supply (very well regulated linear supply) to the radio, the output is still 4W, not 5W.

I will assume that the bran-new Diamond SX200 meter has been calibrated at the factory. Otherwise, I have no means to check its calibration.

What gives?

Frank - KE2KB

new info:
I just remembered that I also have a Yaesu FT-530.
I don't have a battery pack for it, so I plugged the 13.5V supply (same one as I used on the other radios), connected it to the wattmeter using exactly the same cabling, and... 5W!
So the FT-530 puts out full 5W, while the VX-150 and FT-60 don't.
« Last Edit: October 23, 2017, 04:01:26 PM by KE2KB » Logged
K2OWK
Member

Posts: 1273




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« Reply #1 on: October 23, 2017, 04:43:06 PM »

Measuring a VHF radio is not easy, you will need a calibrated watt meter, a precision dummy load for the frequency you are testing, a minimum connection from the antenna terminal to the watt meter to the load. Ten feet of RG-58 is not a minimum connection. A good quality barrel connector from the antenna output to the watt meter to the dummy load will work. Yaesu is a very respectable manufacturer of Ham radios, If they say it tested at 5 watts, I would believe them. See what type of setup they use for testing there radios. I am sure you will find it is a very expensive precision measuring system. Last I would not worry about being one watt low,(if it really is) you will not see any loss of transmission range, because DB loss is very small.

73s

K2OWK
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KE2KB
Member

Posts: 633




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« Reply #2 on: October 23, 2017, 05:45:07 PM »

Measuring a VHF radio is not easy, you will need a calibrated watt meter, a precision dummy load for the frequency you are testing, a minimum connection from the antenna terminal to the watt meter to the load. Ten feet of RG-58 is not a minimum connection. A good quality barrel connector from the antenna output to the watt meter to the dummy load will work. Yaesu is a very respectable manufacturer of Ham radios, If they say it tested at 5 watts, I would believe them. See what type of setup they use for testing there radios. I am sure you will find it is a very expensive precision measuring system. Last I would not worry about being one watt low,(if it really is) you will not see any loss of transmission range, because DB loss is very small.

73s

K2OWK
OK. I will re-test using minimum length connections. But that doesn't explain why the FT-530 produces a 5W reading on the meter.
All of my tests were done at 146.520.
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KE2KB
Member

Posts: 633




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« Reply #3 on: October 23, 2017, 06:09:37 PM »

I did the test again, but with direct coupling between the radio and the meter. I got slightly more than 5W out from the VX-150 using the FNB-83 battery pack with full charge. I did not test the FT-60, but I did test the FT-530. The 530 produced slightly higher reading than the VX-150 did.
I think this is the first time I had ever tested the output of any VHF HT. I never paid much attention to the connectors and cables when reading HF output or even swr. But sure. I fully comprehend the difference between 146Mhz and 7Mhz. I just wasn't using my brain at its max output  Embarrassed
I won't make that mistake again. And I think I could use some new UHF couplings. Some of mine are getting pretty grungy.

I have always thought of ham radio manufacturers as extremely reputable people. I had suspected there was something I wasn't doing right, but couldn't figure out why the VX-150 and FT-60 showed 4W but the FT-530 showed 5. I guess it could be that the 530 has a metallic case, while the other two are plastic? My hand/body could have been acting as part of the circuit? It would make sense then that removing the coax between the rig and the meter would eliminate that factor, since there wasn't anything to radiate. Even though the SWR measured almost perfectly flat with the coax, there was some reflected power...

In any event; it has been a very interesting and informative experiment. Thanks K2OWK.
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N9AOP
Member

Posts: 641




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« Reply #4 on: October 24, 2017, 09:46:42 AM »

I have both those radios.  Using a Bird 43 and the proper slug I measure 5W VHF on both and on the FT60 4W on UHF.  QST did a product review on the FT60 when it came out and got the same results with their test unit.
Art
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