Topband: Bird 43

[Bill Wichers]

Probably not much, you're only a very small percentage outside the calibrated range for that slug. That assumes that the slug is ok (not dropped, etc). 

You can check them several ways. I use a calibrated attenuator after the meter with an hp 436a power meter after that (with the appropriate head). Then just check the slug at several frequencies throughout the range And make sure the bird and hp meters agree within the stated 5% accuracy of the slug. 

You can also use an oscilloscope after the attenuator but you'll need to calculate the power from the displayed voltage on the 'scope that way. Note that you can't just use the 'scope without the attenuator to do this -- the attenuator (assuming a 30db unit) provides the 50 ohm load needed by the bird meter and the transmitter.

You can get used attenuators inexpensively. For short duty cycle measurements you can get by with an attenuator rated at much less than your full output power. Just make sure you don't overheat the attenuator when testing. Optimally you should check the attenuator for accuracy, but they're usually ok in the larger sizes (which are hard to burn up :-). You can do a rough check with an ohmmeter too. 

Sent from my iPhone

On Nov 27, 2014, at 6:36 AM, "Clive GM3POI" <gm3poi2 at btinternet.com> wrote:

> Hi All, With the wealth of knowledge on here I thought I would ask this one.
> Can anyone put a figure on the displayed power using typical Bird 43
> elements for 2-30mhz when used at 1.83.
> 
> My logical guess would be about -5% but have no idea really. 73 Clive GM3POI
> 
> _________________
> Topband Reflector Archives - http://www.contesting.com/_topband