Re: {Collins} Bird 82A



Glen and all,

Thermal conductivity is not the only important parameter for meeting the heat dissipation spec for the 82A. Transformer oil also has a lower viscosity than mineral oil, and that results in more heat being transferred from the resistance element to the outer cabinet via convection currents.

73,
Bob AD3K

> On Oct 10, 2017, at 3:20 PM, scottjohnson1 via Collins <collins@xxxxxxxxxxxxx> wrote:
> 
> Glen I would respectfully disagree.  I think the most important attribute would be dielectric constant, which is all over the map with respect to various transformer oils.  I think thermal conductivity is secondary, especially with Bird loads, which are very conservatively rated.  I do an s11 sweep with my HP 8510C van when I add or change oil, and mineral oil gives the lowest reflectivity.  It also has a fairly low vapor pressure, so it doesn't expand the rubber bellows any appreciable amount.
> 
> 
> Sent from my Verizon, Samsung Galaxy smartphone
> -------- Original message --------From: Glen Zook via Collins <collins@xxxxxxxxxxxxx> Date: 10/9/17  21:01  (GMT-07:00) To: Richard Solomon <w1ksz@xxxxxxxxxxx>, Collins Reflector <collins@xxxxxxxxxxxxx> Subject: Re: {Collins} Bird 82A 
> You really need to use transformer oil and not "regular" mineral oil.  Transformer oil is formulated to dissipate heat more than regular mineral oil can accomplish.
> 
> 
> If you happen to have an electric company "service center", not just a regular office, nearby, you might just "drop by" and ask for a gallon, or so, of transformer oil.  Electric companies purchase transformer oil in 55-gallon, or even larger, containers.  It costs considerably more to handle a small payment for the oil than the oil actually costs.  So, most service centers will just give you some.
> 
> 
> Transformer oil is one of the things that most electric companies don't really keep track of because they use so much a relatively small amount (like 10 to 20 gallons), and the accounting cost is more than what the oil costs.  At least that was the situation for the over 10-years that I worked, as an in-house telecommunications consultant, for TXU which was the electric company for almost half of the State of Texas.
> 
>  Glen, K9STH 
> Website: http://k9sth.net
> 
>       From: Richard Solomon via Collins <collins@xxxxxxxxxxxxx>
> To: Collins Reflector <collins@xxxxxxxxxxxxx> 
> Sent: Monday, October 9, 2017 10:46 PM
> Subject: Re: {Collins} Bird 82A
>    
> Before you spend money on replacement fluid, first determine if you really need it.
> 
> The DL is not completely full of oil, so give it a shake and see how much is in their.
> 
> 
> If is seems low, you need to find out where the leak is.
> 
> 
> In my experience, they are so well made they never leak (unless someone played
> 
> with it). I have never had to top off the oil in any of the DL's I have owned.
> 
> 
>    
> *** You are subscribed to Collins as scottjohnson1@xxxxxxx. If you wish to unsubscribe, or modify your preferences please visit https://mailman.listserve.com/listmanager/listinfo/collins ***
> *** You are subscribed to Collins as rls19@xxxxxxx. If you wish to unsubscribe, or modify your preferences please visit https://mailman.listserve.com/listmanager/listinfo/collins ***
> 
> 




This archive was generated by a fusion of Pipermail (Mailman edition) and MHonArc.