[Lowfer] Re: AMRAD Probe antenna part needed
Chris Trask
christrask at earthlink.net
Tue Jun 10 11:27:14 EDT 2008
Someone earlier made one on vector board using the MPS6521 and MPS6523. He was quite pleased with the results, and those are really cheap parts ($0.22 and $0.10 each from Mouser). I settled on the BFQ19 and BFQ149 as they are very popular for CATV amplifier design and have a higher power dissipation factor.
I've settled on a specific size for the PC board and housing for my active antenna amplifiers, so I had to redesign the AMRAD housing so as to make everything fit.
>
>Chris
>
> Interesting! Thanks for sharing the information. Looking forward
> to building one to test against the others in my arsenal. I'll let
> you know how it turns out.
>
> Jay W1VD WD2XNS WE2XGR/2
>
> p.s. Please keep me posted on any additional information or changes
>
>
>----- Original Message -----
>From: "Chris Trask" <christrask at earthlink.net>
>To: "Discussion of the Lowfer (US, European, & UK) and MedFer bands"
><lowfer at mailman.qth.net>; "Discussion of the Lowfer (US, European, & UK) and
>MedFer bands" <lowfer at mailman.qth.net>
>Sent: Tuesday, June 10, 2008 10:38 AM
>Subject: Re: [Lowfer] Re: AMRAD Probe antenna part needed
>
>
> > 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
>> _______________________________________________
>>>From the Lowfer mailing list
>> Send messages to: Lowfer at mailman.qth.net
>> To sub/unsub visit: http://mailman.qth.net/mailman/listinfo/lowfer
>
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
More information about the Lowfer
mailing list