MFJ Homepage:
<Snip>
"Excellent Balance, Excellent Design
The MFJ-974H is a fully balanced wide range T-Network using four gear driven
1000-Volt air variable capacitors and high-Q air wound tapped inductor for
80-10 Meters and separate inductors for 6 and 160 Meters. The tuning
components are mounted symmetrically to insure electrical balance.
A 1:1 current balun is placed on the low impedance 50 input side to convert
the balanced T-Network to unbalanced operation. The balun is made of 50
ferrite beads on RG-303 Teflon? coax to give exceptional and efficient
isolation. It stays cool even at maximum power."
<Snip>
Here is my read on this device:
It's not a bad tuner for someone who wants to purchase a 100w tuner for
balanced line. There's not much other choice currently on the market. What
I don't like about it is that they advertise it as the successor to the
Johnson matchbox. The little Johnson handled 275w AM or about 500w SSB.
The big one was good for a KW on AM. The MFJ-974H can only handle 300w SSB
(150w CW) and it is a T-Network so it has basically no filtering whereas the
Johnson had excellent bandpass filtering. Also, 12 to 2000 Ohms is a bit
small of a range for matching anything to anything. One will have to do
some good calculating or trial and error antenna length pruning to get the
thing to work well on at least 7 or 8 bands.
In any case, its refreshing to see that the vendors are finally waking up to
the opportunity for selling balanced matchboxes. I commend MFJ at least for
taking this first step. Now maybe someone will build a real successor to
the Johnson.
73
Rick
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|