Low Voltage

[aa4vv]

I have an AIM4170 running Version 845.
When I do a scan I get the following error:

Warning: The internal DC voltage is too low.
Measured Voltage = 6.585
Internal Lower Limit = 7 volts.

I have reloaded / restarted etc.

With the previous version it works fine..
Any suggestions as to what could be wrong?

Thanks Tom AA4VV

[Bob]

The recommended operating voltage limit has been raised 1V in the new version. This does now include the drop of the reverse voltage protection diode. Check the DC voltage at the power connector. If your power supply is not regulated, there will be some droop during a scan. The voltage is checked at the end of a scan when the voltage is likely to be at a minimum.

--73// Bob

[aa4vv]

Do you know if the

PS-12R1A - 12V DC 1 amp LINEAR & REGULATED Power supply 120V AC 60Hz Only - 6ft cord with proper plug - RF quiet $19.00

from Array Solutions will work for the AIM4170?
They list it under the AIM120 but not the 4170

Thanks
Tom AA4VV

[Bob]

Hi Tom,
Yes, it will work with the AIM4170, AIMuhf, and the VNA2180 too.
This one has been evaluated to verify it has a noise characteristic.

A lot of the inexpensive wall warts will work ok as long as they don't have too much droop. Usually this means selecting a PS with a relatively high output current rating since those have large capacitors. It's also important to select one that doesn't output too large a voltage. In principle it's possible to spec a wall wart for an average output of 8V at 300ma even if it has a small output capacitor but it's peak output with a light load or no load may be too high. If there is any doubt about the peak output, check it with a DC voltmeter with no load connected. It should not be more than 15V.

73/Bob

[aa4vv]

"This one has been evaluated to verify it has a noise characteristic."

Thanks Bob for the info. Is the above statement good or bad.
I don't understand what "noise Characteristic" means. Does that mean it is RF noisy?

Thanks
Tom AA4VV

[Bob]

That was a typo. I meant to say "Low noise characteristic".
This particular supply is linear, not switching, which is good if you only need 120 V operation. It is also regulated which is good for more reliable operation.

Some unregulated supplies will work ok as long as the line voltage is within certain limits. Their output may go too low or too high if other loads share the same AC supply line. This can make their performance vary from time to time.

The GPS global power supply is a switcher for 120V to 240V but it does have low noise and it will work with any of the antenna analyzer products.

73/Bob

[aa4vv]

Thanks Bob for your information and patience

73 Tom AA4VV

[s59zb]

Jul 30, 2011 12:24:12 GMT -5 Bob said:

The recommended operating voltage limit has been raised 1V in the new version.

But I steel have a problem, because I power AIM 4170 with 5 AA NiMh batteries which fully charged never have 7 volts. I have two identical battery packs and they supply AIM very well until last version.
Is it possible to optional switch to old recommended operating voltage limits?

73 Zvone, S59ZB

[Bob]

Hi Zvone,

I'm sorry, this is not an option. There is a risk of getting less accurate data if the voltage is too low. It would be possible to disable the test completely but when the voltage gets too low, the change in data might be very hard to detect. If the AIM just stopped working completely, it wouldn't be so bad because you would know something was wrong, but it is a gradual effect.

-- 73/Bob

[parker]

Just a note nine years after this discussion ended - my very old Jameco 9V supply developed an intense 60Hz ripple (1.2 VAC) and it was enough for the unit to shut itself off right after turning it on. I suspect the output voltage sagged considerably under load.

I replaced the wall wart with a 12V 500mA unit with a steady, clean output, and all is good again.