Quad band mobile - diminished power in low VHF

[montyhouse]

I have a Wouxon KG-UV980P (quad band 2m/70cm/6m/10m). At high power, I'm around 47w - VHF, 40w - UHF but then around 15w - 6m. What's the reasoning why the power drops off so much at low VHF?

 

[jeepsandradios]

Assume you have it hooked to a dummy load ?

 

[montyhouse]

Assume you have it hooked to a dummy load ?

Yes. I forgot to add that piece.

 

[jeepsandradios]

Only thing I would suggest is look at your power (DC + Voltage) with a DVM to see if its dropping. I'm not sure how well a radio on chip really performs on that large of a split.

 

[RichardKramer]

I have a Wouxon KG-UV980P (quad band 2m/70cm/6m/10m). At high power, I'm around 47w - VHF, 40w - UHF but then around 15w - 6m. What's the reasoning why the power drops off so much at low VHF?

I have the Yaesu 8900 quad; it has 4 power levels set with the menu. Do you have the power level in the menu set to the highest level?

 

[ko6jw_2]

I have read user reviews complaining of low power output on 10m and 6m. I cannot find any specs for current draw only voltage requirement. Possibly it needs more current than your power supply can provide. Other reviewers seem to have no complaints. A review in QST of the 2m/440 version of the radio in 2015 found defects and they had to test 3 units before they got one that was up to spec. Did not meet spectral purity requirements. This seems to indicate that quality control was poor.

 

[montyhouse]

I have the Yaesu 8900 quad; it has 4 power levels set with the menu. Do you have the power level in the menu set to the highest level?

Yes. I've tested at all four power settings: High, Med1, Med2, Low.

 

[montyhouse]

I have read user reviews complaining of low power output on 10m and 6m. I cannot find any specs for current draw only voltage requirement. Possibly it needs more current than your power supply can provide. Other reviewers seem to have no complaints. A review in QST of the 2m/440 version of the radio in 2015 found defects and they had to test 3 units before they got one that was up to spec. Did not meet spectral purity requirements. This seems to indicate that quality control was poor.

Used power supply at 13.8v. Ultimately, I'd like to be able to remove from my vehicle and hook up to a battery for remote camping usage.

 

[ko6jw_2]

Used power supply at 13.8v. Ultimately, I'd like to be able to remove from my vehicle and hook up to a battery for remote camping usage.

Yes, but how much current does it draw? Does your power supply have an amp meter? What is its rating? These are all questions that could have an effect on power output. Does the voltage drop below 13.8 when you transmit? If so, by how much?

 

[montyhouse]

Yes, but how much current does it draw? Does your power supply have an amp meter? What is its rating? These are all questions that could have an effect on power output. Does the voltage drop below 13.8 when you transmit? If so, by how much?

Power supply: Wouxon SPS31WIN SPU rated to 30A (no amp meter--used multimeter)
Current-standby: 390mA
Voltage drops between 100 (10m)-220 (2m) mV on Tx
Current - All on High Power (which is 47w and 40w, respectively, VHF and UHF)
6m, 2m, 70cm - All between 7.6-7.8A during Tx
10m - 6.6A

All using dummy load

 

[W4EMS]

Could it potentially be an SWR bridge sensing higher SWR and decreasing the power out? Not necessarily what one would expect with a dummy load but perhaps the dummy load is not performing as expected. Just a random thought. Suggest testing with watt meter when connected to a 10 meter antenna and see what the output is.

 

[FKimble]

The manual for this radio does not give power out put for any of the bands. The sales literature shows power out put for VHF and UHF. It does not list an output power for the other two bands. I don't think your radio has a problem. It's just the way it is designed.

Frank

 

[ko6jw_2]

Based on all of the above, it does not sound like the power supply is the problem. More likely this is a characteristic of this radio or this particular radio is defective. The reality is that being limited to FM on 6 and 10 meters won't get you very far. Yes, there are some repeaters, but you really need SSB capability for working DX especially on 10 meters. My first 10 meter SSB radio was from Radio Shack. It's output was 12 watts PEP. My first contact with a makeshift dipole was with an op in Argentina from Southern CA.

 

[montyhouse]

The manual for this radio does not give power out put for any of the bands. The sales literature shows power out put for VHF and UHF. It does not list an output power for the other two bands. I don't think your radio has a problem. It's just the way it is designed.

Frank

I think that's the #1 Family Feud answer.

 

[montyhouse]

The reality is that being limited to FM on 6 and 10 meters won't get you very far. Yes, there are some repeaters, but you really need SSB capability for working DX especially on 10 meters.

Exactly.