Yaesu NC88U strange behaviour

I’m trying to determine if my Yaesu NC 88U battery charger is kaput.

The charger is a small light 12V @ 200mA unit that came with my VX 170 handheld and is supplied with many Yaesu products. It’s small and light enough to be a switched mode device. I don’t expect stunning regulation when off load I do expect OK regulation when charging a battery. The off load voltage is 19V which feels abnormally high for a switcher.

You can display the “battery” voltage on the VX 170. So on battery it may read 7.6V and when you connect the charger from my FT817 the voltage fluctuates for 30secs or so till stabilising at 12.2-12.5V. If I use the NC 88U with VX 170 then the voltage is madly varying… 8.5-13.5V and here, there and everywhere in between and constantly changing.

If you have an NC 88U charger can you measure the voltage off load and when it is charging, I’m guessing most Yaesu modern handhelds will be able to do display the voltage. Let me know if yours does the same or not. I’m thinking the feedback or Vref in mine is kaput in someway which is why the voltage is varying so much on load and so high off load.

Shame if it is broken as it is bijou and petite and doesn’t take up loads of space if I am going away on a SOTApedition. I can always snip the cable and use it as a genuine Yaesu FT817/VX170 power lead. It also fits the Alinco DJ-G7 144-432-1296 handheld as well. That can go to a cigarette light plug and charge the VX 170 whilst driving.

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Hi Andy -
My VX-8GR came with a NC-86B charger - since it’s different than your charger and runs on 120VAC, it may not matter that it puts out ~12V.
HOWEVER, I find that the Alinco and Yaesu HT power connectors are not the same - here is a reference for several radios:
Yaesu HT 4.0mm x 1.7mm (two different HT)
MTR-2b/3b 4.0mm x 1.7mm
SW-3B 4.0mm x 1.7mm
Alinco HT 3.5mm x 1.35mm (two different HT)
KX2/3 5.5mm x 2.1mm

73, Etienne-K7ATN

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The DJ-G7 is most definitely 4.0 x 1.7 Etienne. I had a much older UHF Alinco handheld that used a smaller sized plug.

The NC 88B is a 120V to 12V adaptor with a US integral mains plug and 4.0 x 1.7 DC plug.
The NC 88C is a 230V to 12V adaptor with an EU integral mains plug and 4.0 x 1.7 DC plug.
The NC 88U is a 230V to 12V adaptor with a UK integral mains plug and 4.0 x 1.7 DC plug.

The NC 88U and NC 88C look the same apart from the mains pins but the US one is quite a lot larger.

I thought it would be the same as my VX7R charger, but it’s not. That and the FT-817 both use the NC-72U 12v 500mA chargers
Both of mine show 14.6 volts off load when measured with a DVM.
I’d expect all Yaesu 12v charges to be very similar off-load.

Hi Andy I have two NC-88U’s, one gives 18.8V off load the other 18.9 so your 19V seems pretty standard. Connected to an FT60 they give a reading of about 10.6V on the radio, on a VX-170 about 10.2. My lower voltage on load may be due to the radio batteries being low in charge, they haven’t been toppped up in a long while… HTH!

73 Paul G4MD

Well it’s good that the off load voltage is about the same. I’ll do some more tests on my NC 88U under load. I can understand the voltage dropping on load and that voltage varying as the battery charges but in my case it is jumping about continuously. You can see it start at 11.9 and cycle up and down 11.5 11.2 10.9 10.9 11.3 11.8 12.0 11.9 11.6 11.2 10.9 and so on. Odd.

Resorted to the manual and found out how to switch on the permanent voltage display :-s
Same behaviour being shown here on the FT-60.


I put the power cable I use to power the VX170 on a summit on a shack PSU set to 12V. VX170 display was rock steady showing 12.1V. On the NC 72U (came with 817) it shows 12.1 12.2 12.3 12.2, i.e. bobbling about around a nominal 12.2 V and so it’s just the NC 88U that have this strange behaviour.

It makes me think the PSU is barely capable of providing the charging/operating current. Anyway, as mine is the same as yours I’ll treat it as in spec.

Thanks Paul.

You’re welcome Andy :slight_smile:

Yes the manual does state that "…NC-88 is not designed to power the transceiver for operation (reception or transmission) " so since the radio has to be switched on to get the voltage display I guess it pushes the PSU beyond it’s limits.

My VX170 manual is currently AWOL :frowning: Time for a shack tidy this weekend.