[Lowfer] Re: AMRAD Probe antenna part needed

[Chris Trask]

     Slight correction.  The OIP3 and OIP2 for my amplifier using the BFQ19 and BFQ149 are +44.25dBm and +68.5dBm, respectively.


>
>     The AMRAD antenna amplifier is yet another active antenna circuit that is in serious need of an overhaul.  It suffers from the same design shortcoming as the Lankford complementary push-pull amplifier, which is that it is dependent upon very expensive and difficult to obtain parts.  In the case of the Lankford amplifier, the 2N5160 transistor costs $10 each and is an obsolete part still made by Microsemi for maintaining existing cable TV amplifiers.  The AMRAD antenna uses the CP666, which costs an astounding $17 each from another single source.
>
>     Designing circuitry with excessively expensive and elusive components is a sure way to cause people to lose interest, regardless of the degree of performance.  Earlier this year I undertook the task to redesign the Lankford amplifier so as to make use of readily available parts, reduce the cost, and improve the performance.  The first effot made use of mundane parts such as the J310, 2N2222, and 2N2907 and achieved the desired results.
>
>     The design was furthered by modification of the JFET input stage, first using an active source load and later with a complementary pair, adding a J271 P-channel JFET.  The output devices were changed to the Philips BFQ19 and BFQ149, and the amplifier now outperforms the both the Lankford and AMRAD designs, having a measured OIP3 of +39.75dBm and OIP2 of +59.5dBm.  Frequency response is flat from 30kHz to 91MHz.  All of the components are readily available from Mouser, and the BFQ19 and BFQ149 transistors cost $0.92 and $1.13 each in small quantities.
>
>     I made an initial PC board for these, but there is a slight defect in the design.  I'm going to revise the board and have more made after various people have built and evaluated the design using the present board.
>
>     The details for this amplifier can be found at:
>
>     http://tinyurl.com/2gkndh
>
>and construction details for the waterproof housing are at:
>
>     http://tinyurl.com/27jw5a
>
>
>
>
>-----Original Message-----
>>From: "James M. Walker" <chejmw at buffalo.edu>
>>Sent: Jun 10, 2008 6:50 AM
>>To: "Discussion of the Lowfer (US, European, &  UK) and MedFer bands" <lowfer at mailman.qth.net>
>>Subject: Re: [Lowfer] Re: AMRAD Probe antenna part needed
>>
>>Thanks Steve,
>>I tried the web-site a little while back, and got no active areas for
>>purchasing the thing. Basically no response from the server.
>>
>>Looks like a new site and web-pages. Will give them a call and order a pair,
>>just in case.
>>73
>>Jim
>>WB2FCN
>>
>>----- Original Message ----- 
>>From: "Steve Ratzlaff" <steveratz at wildblue.net>
>>To: "Discussion of the Lowfer (US, European, & UK) and MedFer bands" 
>><lowfer at mailman.qth.net>
>>Sent: Tuesday, June 10, 2008 8:54 AM
>>Subject: Re: [Lowfer] Re: AMRAD Probe antenna part needed
>>
>>
>>> Hi Jim,
>>> Why not order directly from the factory? CP666 is currently $17.50 each.
>>> http://crystalonics.com/  "E-mail: pweinstein at crystalonics.com"
>>>
>>> 73,
>>> Steve AA7U
>>> NE Oregon
>>>
>>> ----- Original Message ----- 
>>> From: "James M. Walker" <chejmw at buffalo.edu>
>>> To: <lowfer at mailman.qth.net>
>>> Sent: Tuesday, June 10, 2008 2:56 AM
>>> Subject: [Lowfer] Re: AMRAD Probe antenna part needed
>>>
>>>
>>>> Howdy folks,
>>>> Long shot time here. First the problem, back when we had the 90 MPH
>>>> winds here in Buffalo, I had serious static build-up on my AMRAD antenna.
>>>> Sounded like bacon frying during the episode.
>>>>
>>>> The result was the active component of the "Probe" was fried!
>>>> SO I am currently looking for a replacement and possibly a spare as well
>>>> for the Crystalonics CP666 device. Anyone had an extra laying around?
>>>> Please answer direct to my Email address with quantity and price for item
>>>> and shipping.
>>>> Thanks for your help.
>>>> Jim
>>>> WB2FCN/WD2XSH-22
>
>

Chris

     ,----------------------.       High Performance Mixers and
    /    What's all this     \    Amplifiers for RF Communications
   / extinct stuff, anyhow?  /
   \  _______,--------------'           Chris Trask / N7ZWY
  _ |/                                  Principal Engineer
 oo\                                  Sonoran Radio Research
(__)\       _                             P.O. Box 25240
  \  \    .'  `.                     Tempe, Arizona 85285-5240
   \  \  /      \
    \  '"        \                 IEEE Senior Member #40274515
     .       (  ) \
      '-| )__| :.  \              Email: christrask at earthlink.net
        | |  | | \  '.       http://www.home.earthlink.net/~christrask
       c__; c__;  '-..'>.__

                       Graphics by Loek Frederiks