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I have recently purchased a Celestron Dew Heater Ring (9.25") and a Pegasus Powerbox Advance (Gen2). However, when I run the heater ring at anything from about 30% to 90% there is a pronounced "ringing" sound coming from the powerbox. The sound reminded me of that which can be heard from a mains lighting dimmer switch, but at a higher pitch.

There is no sound when using traditional dew straps alone. Of course it returns as soon as the dew ring is also attached.
The sound is at its worst when the ring is attached to a dew heater output of the powerbox.
When instead used with an in-line PWM LED dimmer attached to a 12V output of the powerbox, the noise is less, although still noticeable. Interestingly, the noise is also present if the dimmer/heater ring is connected to the same observatory 12V supply before its connection to the powerbox, although is further reduced.

I also have a Gen1 version of the powerbox, which again produces some noise, but it is significantly less that the Gen2 powerbox.

The fact that there is still noise, albeit it less, even when the heater ring is connected to a non-powerbox 12V supply suggests to me that there could be some type of feed back or interference that is affecting the powerbox, and that this is more pronounced in the Gen2 version.

So, my question is has anyone else experienced this issue? Or indeed, is using a Celestron heater ring with a Pegasus Powerbox without this issue? Or is there an incompatibility between the heater ring and the powerbox? Or, is there a fault with the heater ring?

I have Googled for some answers, but to no avail.

I suppose that I could power the heater ring from a completely different 12V supply, but that rather defeats the point in having a powerbox.

Any thoughts?

Adrian

15 hours ago, 1parsec said:

You can increase the clearance of the belt so the belt teeth don't touch by loosening bolts 'A' and moving the motor plate downwards a bit and re-tighten 
Then loosen bolts 'B' and move the motor upwards to tension the belt.

You are looking to increase the distance between the idler roller and the motor 9T pulley.

Many thanks for everyones advice and I have also ordered a replacement belt from Rowan Astronomy

I have a HEQ5 rowan belt conversion which has been in situ for a few years, although not heavily used. However, my guiding has not been particularly good and so I removed the cover to check the belts. I have noticed that the RA belt is buckled and when running actually catches on the teeth of the belt running in the opposite direction, which can clearly been seen in the photograph.

Has anyone else encountered this and what did they do to resolve it?

Thanks
Adrian

20 hours ago, david_taurus83 said:

Here you go! Run APT and under the tools tab make sure the Histogram button is on.

 

 

Then under the Img tab navigate to your folder. Clicking on one of the small previews on the right loads it onto the main screen.

 

On the Histogram bar press Auto-Str L and voila!

 

 

 

That's great, many thanks

Adrian

18 minutes ago, mikeyj1 said:

As you are moving from the DSLR, why aren't you comparing it to that? 

sorry but surely the 120mm on a different scope cannot give you any kind of meaningful comparison really..

interested in the discussion however, as i had been considering the 294c also

Good luck

Mike

Thanks Mike. It was all a bit "last minute" and the battery on the Canon 600D needed charging, but you're right I need to do a comparison. On the whole the 600D works well, but is noisy when the sensor gets warm.

15 minutes ago, david_taurus83 said:

I get off M42 J2 almost every night on way home! Think my LP is probably worse lol

 

Yes, in Sharpcap you can adjust exposure, gain, offset (brightness) with sliders on the right. It continuously loops frames as well.

 

Just a thought about what's been said above, did you perform a stretch to the preview in APT? The default preview is no stretch?

Hope you don't have to go via M42 J3 as the roadworks are causing big delays 😞

I didn't perform a stretch, so I'm wondering if that was part of the problem

9 minutes ago, Anthonyexmouth said:

I always thought the SW guide was @190mm . At least that's what I've always used for settings on mine when I used it with phd2. 

Not sure how much difference that makes on your calls. 

Mine is 242mm, F/4.8 

https://www.firstlightoptics.com/guide-cameras/sky-watcher-evoguide-50ed-guidescope-zwo-asi120mm-bundle.html

5 hours ago, dunc said:

You should use SharpCap Pro to do an analysis of your imaging train and suggest an exposure, gain and offset. I have a 294 and for my sky (which is quite dark when the streetlamps go out at 11pm) it recommends E250s G121 (unity - my choice) Offset 4 (yes 4) and I get very nice images

Duncan

Thanks. I only use the ASCOM derived Unity settings (G120, O30) last night, so optimising this would be a good start

1 hour ago, vlaiv said:

Not sure if it's the "speed" of the imaging scope vs guide scope that can explain this.

SW guide scope is F/4.8, or has focal length of 242mm, while imaging scope is F/7.5, or 900mm FL.

With ASI120 guide scope gives resolution of 3.2"/px, while imaging resolution is 1.06"/px.

Gathering surface of 120mm scope is 14400mm2 while that of 50mm scope is 2500mm2, ratio of these two is 5.76.

Ratio of pixel surfaces is 9.11.

Guide camera will gather x1.6 more light per exposure - that is not significantly faster to explain what's been observed (8s exposure from ASI120 should match 12.8s exposure from ASI294 - provided same QE).

If we assume that no extraordinary conditions arose - like dew on scope, or fogged up / iced up camera, only explanation that I could offer is matter of histogram stretch for preview.

ASI120 is probably working in 8bit mode, so ADUs are directly mapped to 0-255 monitor output. ASI294 is however working in 14 bit mode, that means 6 bits of difference, or x64 in intensity if we assume 14bit -> 8bit straight mapping. What is obvious in image from ASI120 in unstretched image will be very faint, almost invisible in x64 less bright unstretched image from ASI294.

Someone with more knowledge of APT could advise how to manipulate histogram for preview (is there auto stretch functionality or alike?)?

Many thanks for your detailed reply. I agree, I'd have expected the additional light gather to have compensated for the slower speed of the ED120, which is why I was surprised. There was no dew on the lens and yes the ASI120 was in 8 bit mode.

I'm new to APT and it's complex compared with my previous BackyardEOS. I need to do some more reading 🙂

1 hour ago, david_taurus83 said:

Try using Sharpcap for testing as suggested. It gives you much more control over the camera 'in session' whereas with APT you have to temporarily disconnect to access the driver settings to change gain and offset.

Thanks, I will. Only just noticed your location. You can't be too far away from me, we probably share the same light pollution!

I’ve recently purchased a ZWO ASI294MC-PRO and last night was first light for this on my SW 120ED.

Conditions were not ideal for imaging, but to familiarize mysef with the camera I setup a comparison with the SW 50mm guidescope / ASI 120MM Mini using Sharpcap and APT. I had great hopes for the 294, especially in terms of sensitivity, but I have found that the 294 appears far less sensitive than the 120MM.

As an example, M57 using the 120MM with a gain of 54 and an 8 second exposure clearly showed the object and a multitude of stars. Whilst the 294 on the 120ED showed a much fainter M57 with only a few stars present. Only by increasing the gain on the 294 to >500 were the images comparable, but this then resulted in much greater noise.
It was a similar situation with M51. Using APT with a 2 minute exposure, there was no sign of the object using the 294, but it could be seen with the guidescope/120MM.

I’d be grateful if anyone could provide advice on this or indeed guidance or a link for initial settings to use with a 294. I realise that the migration from DSLR to a CMOS/OSC is a steep learning curve and so I’d like to eliminate user error before contacting FLO about a potentially defective camera.

Many thanks
Adrian

I tried using a Logitech Gamepad F710, but found that the wireless connection was frequently lost, usually part way through an observing session. I later read a report that buttons on the F710 can be susceptible to moisture.

I now use a wired gamepad, which although less convenient never looses a connection.

Adrian

The ISS can be picked up with very basic equipment. I managed to hear Tim Peake when he was aboard using a handheld Baofeng UV-5RA.

looking forward to seeing the finished pier/obsy Adrian . it would have looked nicer white mate, to go with the mount.

Sorry about the shameless plug, but Gonzo, he got it from me, I make them to order, either eq5/heq5 or eq6. drop me a pm if you are interested mate.

gaz

You're probably right about the colour, but I can paint the pier black to match which will help

Adrian

Just received my latest toy. Now I just need to build my pier . . . . . and then an obsy!

Adrian