[Boatanchors] Resitors
J. Forster
jfor at quikus.com
Tue Jul 9 12:26:55 EDT 2013
I forgot to reply yesterday. Sorry.
You are much better off using roughly e3qual value resistors in series to
make what you want for HV use, rather than paralleling resistors to make
the wattage.
In series, the voltage divides along the chain.
Remember, resistors have:
A voltage limit, irrespective of value.
A power limit, based on V*V/R
A current limit (low values mostly)
You must honor ALL the above.
-John
=================
> The wattage rating is probably for voltage breakdown of the resistors, so
> if
> you must use lower wattage then parallel is a no no. Use a series
> connection to make the required resistance and needed wattage if
> necessary.
>
> Mike W6MXV
>
> -----Original Message-----
> From: Rob Atkinson
> Sent: Monday, July 08, 2013 10:39 PM
> To: telegrapher at q.com
> Cc: Boatanchors
> Subject: Re: [Boatanchors] Resitors
>
> Try getting pairs of 1 or 2 W. 6 and 10 Meg if possible and parallel
> them? Don't know--those values may or may not be even harder to find.
>
> I think there are some other methods for setting up a h.v. audio pick
> off involving multiple resistors in series for a voltage divider
> network. I don't see why they have to be so high watt. The scope
> isn't going to draw much current on the very high Z vertical input.
>
> Rob
> K5UJ
>
> On Sun, Jul 7, 2013 at 6:44 PM, <telegrapher at q.com> wrote:
>> Looking for a couple resistors, 2 or 3 W, 3.0 Megohm and 5.1 megohm.
>> That
>> is the values in the modulator off the HV line that goes to the scope
>> for
>> looking at the waveform going into the 100TH's. I would have thought
>> maybe they would both have the same value as they are in series but not
>> so
>> according to the color codes. Most stuff these days is 1/4 or 1/2 watt
>> or
>> less. going above that to the 3 + watt level gets a tad bit more
>> expensive. The existing ones of which the 5.1 meg unit is open are what
>> looks like the older carbon type. Now i see they have some glazed glass
>> types. DO you have any experience or knowledge of what these are like
>> or
>> how reliable?
>> NOt a lot of space here, maybe 2 inches so putting more than 2 in series
>> won't fit.
>>
>> Larry
>> W0OGH
>>
>
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