Pegasus Astro Forum

I just got a Pegasus Ultimate Power Box v2.

I'm powering PUPBv2 with a 30amp Astron power supply. A very clean linear power supply.

I'm using the UPBv2 (at the moment) to power, and supply USB, for a QHY camera, and run a single dew heater strap.

One thing I noticed was a lot of audio noise coming from the dew heater strap. (I'm using a DewBuster heater strap which I've had for quite a while and it never made any noise before.)

I also tried different ports on the UPBv2: I had the single dew heater on port A. I also tried port B -- no difference in sound.

My understanding is the powerbox uses pulse modulation on the Dew heater output. It "sounds" like it is pulsing at something like 1000hz.

I previously used a DewBuster manual-dial controller, and it also "pulsed", but the DewBuster ran at like 1 hz... I never heard any sound.

This noise if very annoying.

Can I work around this problem?
Will some ferrite chokes help? (I wouldn't think so.)
Does this happen with other Dew Straps?

Btw The Ultimate PB v2 is currently running firmware version 2.4, in case that matters.

thx for any suggestions.

-Jeff

Hi Jeff,
Honestly this is the first time I hear this.
Probably something inside your specific Dew strip is tuned to this frequency.
The UPBv2 has been used with a wide range of heaters from different brands but
we never had a similar issue.

Unfortunatelly we cannot change the frequency (current PWM is indeed close to 900Hz).
A change in frequency is something that affects lots of other functions of the UPBv2.

ok.. thx for the info. I have two other dew heaters (same brand). The one I'm using fits the telescope.

However I can test the other heaters once I get a chance. (One is longer, the other is shorter, than the one currently on the telescope.)

-jeff

It turns out my dew heater straps are from Kendrick. "Dew Remover" is the brand.

I have three...
- A really long one for an SCT.
- One that fits the 5" refractor just about right.
- A really really short one.

It turns out only the really long one is making noise.

I switched to the medium length Dew strap and no more ringing noise.

I should probably replace these old dew straps... maybe.. I don't know if they are better, as good as, or worse than what's available today.

thx