You can make a non-polarized capacitor by connecting two polarized electrolytic
back-to-back (negative ends together). As I recall, the overall capacitance
will be half of the two caps.
73,
Jack, W6FB
> On Feb 10, 2024, at 11:43 AM, Joe Subich, W4TV <lists@subich.com> wrote:
>
>
>> I managed to find about 14uF worth of non-polarised capacitors, so cobbled
>> them all together and connected them across the CW and CCW
>> leads.
> That's probably not enough to be significant.
>
> From an HVAC blog I found a formula for determining the value of a
> run capacitor (note the HVAC folks deal with much higher voltages
> and currents!). The formula they give is: C(uF) = (2652 * I)/V
> where I is current through the capacitor and V voltage across the
> capacitor.
>
> In both the Emotator and CDE/HyGain cases, the common motor current
> is about 2 A (1A in each winding) or about 1A through the cap (Hy-Gain
> is specified at 24VAC/2.25A). Using the Hy-Gain numbers which are
> consistent with Emotator's 70 VA rating that works out to 125 uF.
> The 100 uF Emotator cap may be a bit undersized while the CDE/HyGain
> 130-156 uF cap may a bit closer to optimum.
>
> I'd be strongly betting on a weak capacitor ... the trick will be to
> find an appropriate motor run capacitor that will fit in the Emotator
> case.
> 73,
>
> ... Joe, W4TV
>
>
> On 2/10/2024 11:47 AM, Roger Parsons via TowerTalk wrote:
>> Many thanks to Joe W4TV and Mike W4EF for their most helpful replies.
>> I managed to find about 14uF worth of non-polarised capacitors, so cobbled
>> them all together and connected them across the CW and CCW leads. (I should
>> point out that we are having unseasonably warm-ish weather at the moment so
>> my tests are inconclusive!) The antenna rotates, but the phase difference is
>> now about 120 degrees instead of 90. I think that implies that the original
>> capacitor is still operational, but of course there are number of ways in
>> which a capacitor can fail. If that failure is resistive leakage then the
>> extra capacitance might not help. I am quite confident we will get some
>> horribly cold weather quite soon and I can then repeat the test.
>> I did already have a copy of the instructions for the units, but not the
>> marketing brochure which does contain some useful information. The
>> schematics in the instructions are all wrong, certainly when compared to my
>> unit: My transformer has two secondary windings - the tapped one for the
>> motor drive and a separate one for the control/indication. Also, the
>> transformer is clearly marked as 28V. I did purchase the equipment a long
>> time ago when I was G3RBP so it is 240V 50Hz but I can't see that would make
>> any difference except for a small phase change.
>> Anyway, thanks again for the help.
>> 73 Roger
>> VE3ZI
>
>
>
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