In article . com,
N9NEO wrote:

I am going to order some of the crystalonics Jfets for the Amrad
antenna. My friend recently built the antenna and he gives it two
thumbs up. The fets are priced at I think $14.75 for 2001 prices. I
have asked Crystalonics to hold this price and I am awaiting word
back. I will order a few extra so if anyone is interest in building
the antenna ask me for fet now. The reason I bring this up to group
its that the antenna is very good, and Crystalonics doesn't really
like selling one part at a time. If you have no idea what I'm talking
about then email me and I will send you pdf if you want.

That is a high price for a transistor that operates at HF.

--
Telamon
Ventura, California

On Jun 14, 4:17 am, Telamon
wrote:
In article . com,

N9NEO wrote:
I am going to order some of the crystalonics Jfets for the Amrad
antenna. My friend recently built the antenna and he gives it two
thumbs up. The fets are priced at I think $14.75 for 2001 prices. I
have asked Crystalonics to hold this price and I am awaiting word
back. I will order a few extra so if anyone is interest in building
the antenna ask me for fet now. The reason I bring this up to group
its that the antenna is very good, and Crystalonics doesn't really
like selling one part at a time. If you have no idea what I'm talking
about then email me and I will send you pdf if you want.

That is a high price for a transistor that operates at HF.

--
Telamon
Ventura, California

Yes, can't argue that point. Won't be stocking up on that one.
Supposedly some kinda magic inside relating to third order intercept
or something like that. Anyway my friend down the street built one
and he likes it A LOT. So here I go.

73
NEO

On Jun 14, 3:17 am, Telamon
wrote:
In article . com,

N9NEO wrote:
I am going to order some of the crystalonics Jfets for the Amrad
antenna. My friend recently built the antenna and he gives it two
thumbs up. The fets are priced at I think $14.75 for 2001 prices. I
have asked Crystalonics to hold this price and I am awaiting word
back. I will order a few extra so if anyone is interest in building
the antenna ask me for fet now. The reason I bring this up to group
its that the antenna is very good, and Crystalonics doesn't really
like selling one part at a time. If you have no idea what I'm talking
about then email me and I will send you pdf if you want.

That is a high price for a transistor that operates at HF.

--
Telamon
Ventura, California

Yes, but hes JFETSa re bullet proof. No one else makes anything even
close.

http://www.crystalonics.com/jfets.htm

" Broadband R.F. Amplifiers N-Channel JFETs

* High Dynamic Range
* Useable Through 500 MHz-CP643
* Low Noise Figure- 2.2dB Typ., CP640
* 50 Ohm VSWR 1.5:1 0.5-50 MHz
* 3rd Order IM I/P +40dBm

Device Type Geometry BVDSO V Min. Gm mMhos IDSS Typ.mA VPO Package

Number
CP650 424 25 150 600 2-10 TO-5/HSOT-23
CP651 424 20 100 300 2-10 TO-5/HSOT-23
CP664 424 30 100 400 2-10 TO-5/HSOT-23
CP665 424 40 100 400 2-10 TO-5/HSOT-23
CP666 424 50 100 400 2-10 TO-5/HSOT-23
CP640 424 20 100 400 2-10 TO-5/HSOT-23
CP643 446 30 40 100 2-7 TO-46/HSOT-23"

Check out Dallas's designs at http://www.kongsfjord.no, under the
Dallas Files,
"Some of My Favorite Small Antennas for MW and LW"

The intercepts he has achieved are fantastic, especially the dipole
versions.

Even the simpler, and less expensive, U310/2N5109 are great.

FWIW and IMO the Crystalonics JFET designs are worthy of only the very
best
receivers. The IMD products of the simpler unit is much better then
the average
SW receiver. By average I mean a R5000, any of the Lowes and the like.

An R8B or AOR7030+ clearly deserves the better and more expensive amp.
I have no experience with any Icom HF receivers so I have no idea if
they would
benefit.

The Crystalonics amps are the only active antenna that doesn't fold
under the
770 and 1240 nearby MW stations. His U310/2N5100 doesnt realy fold,
but I do
get very minor mix + and mix - artifact that is clearly the amp and
not the receiver.
My older Datong

Given that a good quaility coax terminated at 50 Ohms will produce a
S3 on
most receivers shows how strong the RF is at my home.

Chris over in the loop antenna group has a modified version of
Dallas's simpler
amp that might be worth investigating. Similar JFET, he uses the J310
which is
not quite at good as the U310 but shouldn't make a lot of difference
except in the
worst locations, but he uses a 1:3 transformer between the fet and
theBJT.

If you are going to build active antennas then you have to use the
best devices
available for even minimaly acceptable results.

Even the North Country active antenna will perform much better with a
U310 instead
of the stock JFET.

My older Datong AD370 goes completly nuts and a stock North Country
fairs even worse.
By "nuts" I mean lots of spurs all over MW and HF. Even the McKay
Dymek D100, or
whatever the active antenna they sold in 2004, acs badly with many
spurs.

Terry