[Boatanchors] GR 1606A RF Bridge question

[Mike Hanz]

Like Dick, I don't see any problem with your procedure - as far as it 
goes.  I've measured a number of antennas with my 1606A, and if I got 
something wildly different from what I expected, I have learned with 
regret that what I expected was usually wrong to start with, or there 
was something wrong with the setup *externally* to the 1606A.  Where did 
you get the assumed value of the antenna reactance?  What assumptions 
were made in those calculations?  How did you make sure that the virtual 
counterpoise in the ground was solidly connected to the 1606A ground 
with a low impedance path?  How did the long wire get from outside to 
the 1606A - does it go through any or near any conducting material?  Is 
the house siding conductive?  Those are the sorts of questions I ask 
myself now, when things seem screwy. Throw in a transmission line and it 
gets even more complicated.

73 - Mike  KC4TOS

On 6/27/2014 2:01 AM, Richard Knoppow wrote:
>
> ----- Original Message ----- From: "Ispoulin--- via Boatanchors" 
> <boatanchors at mailman.qth.net>
> Sent: Thursday, June 26, 2014 1:29 PM
>
>> I have a question on the  procedure for testing  antenna impedance with
>> the General Radio 1606A RF Impedance bridge. I interpreted the manual as
>> saying to do the initial balance with the unknown input shorted to 
>> ground and
>> the detector (HF Receiver), and signal generator at frequency of  
>> interest
>> connected,adjusting for a null on the receiver........This resulted 
>> in a lower than  expected
>> reactance for the antenna,which I assumed  to be around 1,000 ohms  
>> for an
>> end-fed long wire.
>
>     I think your procedure is correct.  I read over the handbook to 
> make sure my memory is correct.  The reactance reading is the 
> difference between the setting for the initial balance and the reading 
> for the final balance divided by the frequency in Mhz. The resistance 
> reading is constant with frequency.  However, there are some 
> corrections to be applied to the raw readings to obtain the true 
> values. There are procedures and charts for the corrections in the 
> handbook. I am tempted to set this up in my shack with my 1606-A but 
> its a little late:-)
> -- 
> Richard Knoppow