[Elecraft] Balun BL2

[Ron D'Eau Claire]

Keep in mind that the only source of the heating in the core is the RF power applied. Every watt used to make heat is a watt never radiated. 

A hot core will eventually reach its Curie temperature that causes the inductance to drop to a very low level. At that point it is no longer functioning as a balun, transformer or whatever.

73, Ron AC7AC



-----Original Message-----
From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Walter Underwood
Sent: Thursday, May 26, 2016 8:46 PM
To: Elecraft List
Subject: Re: [Elecraft] Balun BL2

You might look at the “QRP” baluns from Balun Designs. They are designed for 250 W and cost about $50. Excellent design and construction.

http://www.balundesigns.com/low-power-qrp-baluns/ <http://www.balundesigns.com/low-power-qrp-baluns/>

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)

> On May 26, 2016, at 6:04 PM, jsodus at comcast.net wrote:
> 
> Hello,
> I'm contemplating buying the BL2 balun. 
> It would be connected to 450-ohm transmission-line, which would go to a version of W1AB's "killer-antenna", sized for 20m on a 31' jackite-pole. 
> 
> A reviewer of the BL2, on eham five years ago, commented about heat and signal-loss. 
> The heat and signal-loss concern me, not at the QRP-level but higher wattage. 
> I realize it is spec'd at 250 W but how hot does it get? 
> 
> I've looked for data about insertion-loss for the BL2 and came up short there. 
> Hopefully someone has measured the insertion-loss and could share that data. 
> 
> The "elecraft BL2 assembly and operating manual" has the cores as ferrite material. 
> But ferrites exhibit non-linear properties, so the loss may be a function, not only of frequency, but also drive-level. 
> Insertion-loss shows up as heat and that heat affects the properties of the ferrite. 
> 
> As I wrote above, I'm not concerned about QRP operation. 
> If I put it into operation on FD and but take my KX3 home for the day, what happens if a club-member connects his 100+ W rig to the antenna-system to operate thru the night? 
> TIA for any reply. 
> 
> 73 Jerry KM3K
> KX3 #6088
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