LF: Re: J310 IMD figures

["Jay Rusgrove" <JRusgrove@comcast.net>]

Roelof

 

Had an opportunity to build 6 of the Amrad CP666 e probes (for a military customer) a while back and measured the following. First column is measurments from the QST article, second column is measurment average of the 6 antennas built (all measured within a dB or so of each other), third column Amrad circuit with single J310 at 12 volts and fourth column single J310 at 24 volts.

 

Measured significantly higher IP2 than the original article leading me to believe there might have been a measurement error in the original article...or I got a batch of CP666s that were unusally good performers. The fact that the J310 at 12 volts achieved +50 dBM makes me lean toward possible measurement error in the original article.

 

Hope these columns stay lined up when passing through the reflector! 

 

 

                      Amrad article         W1VD built           J310 12volt       J310 24 volt
                       
 
1 dB comp.    +25 dBm                +25 dBm            +17 dBm            +18 dBm
 
IP2                +53 dBm*              +60 dBm             +50 dBm           +60 dBm
 
IP3                +37 dBm                +36 dBm             +32 dBm           +32 dBm

 

Gain              -16.7 dB                 -16.5 dB               -10 dB              -10 dB

 

* possible measurement error

 

Jay, W1VD

----- Original Message -----

From: "Roelof Bakker" <roelof@ndb.demon.nl>

To: <rsgb_lf_group@blacksheep.org>

Sent: Thursday, February 02, 2006 6:34 AM

Subject: LF: J310 IMD figures

> Hello all,
> 
> Thanks to Andre Kesteloo for forwarding 
the update on the AMRAD active whip 
> design and pleased to see that the 
CP666 is still available.
> 
> Regarding the advice for substuting 
the CP666 for a J310 and the quoted 
> second and third order IMD figures, 
I have measured these and found IP2 = + 
> 65 dBm and IP3 = + 30 dBm. At 
12 volt the J310 should be biased for 10 -12 
> mA, excellent for battery 
operation. These figures are in the same league as 
> for the CP666 and I 
am tempted to purchase one and find out if there is any 
> difference in 
practice.
> 
> Best regards,
> 
> Roelof Bakker, pa0rdt 
> 
>