I must admit to not understanding what MFJ means by input power versus
output power. I figure output power is what comes out of the amp on the
way to the antenna, with the tuner in between... OK... but I don't get
what they mean by "amplifier input power" - which I have read in the
catalog descriptions.
It is just this sort of doubletalk that sent me to Palstar for a pair of
tuners.
My big stick has an 4:1 Un-Un made by DX-Engineering. It came with a
4:1 current balun that worked fine (the original balun was a 4:1
combination current balun and and RF choke design that is supposed to be
OK, but after Zero-5 was caught peddling the wrong type balun (a voltage
balun) from ArraySolutions, then Array Solutions got wise and quickly
supplied a proper Un-Un. There was some flap on this on qRZ.com where
some Dutch ham complained and the guys on the forum figured it out (He
re-wired his to the correct configuration and it worked swell after
that...) Soon thereafter, DX-Engineering came out with its 4:1 Un-Un.
Long story, but I was there all the way, and DX-Engineering
practically gave me the new design Un-Un because I was fairly prominent
in promoting the product on various web discussion groups.
Coincidence ? Yes, absolutely !
I like the guy at Balun-Designs. He made the one I use on my OCF
dipole. He and I had quite a nice discussion about where to put the
feed point in order to maximize performance on 15 meters, and lower
overall impedance to around 200 ohms (referencing our previous
discussion thereon.)
I agree that, if I were to try one of these newer MFJ tuners, I would
probably pick the legal limit model, and then only run about 500 - 600
watts at most, keeping everything conservative. I don't like to stress
the amp, either. It is not worth it, and does not really get you any
more S-meter units.
========================= JHR ================================
On 11/30/2011 9:53 PM, Rick - DJ0IP / NJ0IP wrote:
What James, a Chinese product with quality issues?
Are you serious?
;-)
Now I'll be serious and say that the CG-2000 which is the low power version
MFJ is re-badging, in the meantime is shipping at a pretty good quality
level. It wasn't always. That of course is no assurance that the bigger
versions will have no quality issues. In fact my experience, having worked
with the Chinese a lot is that you have serious quality issues with every
new product, much more so than we know it with new products made in our own
countries.
Also, as Geoff pointed out earlier, these power ratings of 1500 and 600 are
misleading and possibly bogus.
Besides being subject to the same rules of all matchboxes, "when the SWR is
higher, you have to reduce power", we also need to understand if these new
boxes are still rated with the "old" MFJ rating system of "SSB Input Power".
If so, then you can halve those power ratings immediately before you even
unpack it. A straight forward question to MFJ tech support should get an
answer to this, if you can get an answer from them.
My hunch is that this unit is actually rated in output power because that's
how the CG-2000 and CG-3000 are rated.
Just don't forget the bit about reducing power when the SWR is high.
Now in its manual it says:
Features
. Automatically matches antennas from 12 to 1600 ohms impedance (SWR up to
32:1)
. Handles 1500 watts SSB/CW
Here it does not specify whether it is Input Power or Output Power.
In the specifications section it is also vague.
Unfortunately there is no schematic, so I could not see the voltage ratings
on the capacitors.
The matchbox is rated to an SWR of 32:1, or 1600 Ohms.
There is a long paragraph explaining how to add additional feedline lengths
when you get impedances which cannot be matched. Same as in every other
matchbox's manual.
So James, I guess the big question is, will your big stick present an
impedance on any band which is above 1600 Ohms?
I would suggest using a 4:1 Unun (I sourced one from Balun Desgins just for
this purpose). If you have a good 4:1 balun, you only have to re-solder one
wire and it's an Unun.
You may find that you have to switch the unun out on some bands, especially
the low bands.
Finally, being as you only run 600w anyway, you shouldn't have a problem
with it, especially if you use an Unun where required.
73
Rick
-----Original Message-----
From: tentec-bounces@contesting.com [mailto:tentec-bounces@contesting.com]
On Behalf Of Richards
Sent: Thursday, December 01, 2011 1:20 AM
To: Clayton Brantley; Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] Jupiter Autotuner upgrade?
MFJ has a new remote auto tuner that costs about $750 - supposed to
handle 1500 watts. They have one that handles 600 watts for $400.
Some of use with 43 foot monopole vertical antennas are waiting to see
how the first user reviews look before we dive into an MFJ product. I
suspect they are made by the same Chinese outfit that made similar
tuners formerly sold by Array Solutions - but Jay Terleski the owner
said they dropped the line over quality control issues. At that time,
they had one that could handle 800 watts. I suspect (hope, actually)
that if they are from the same manufacturer, they have been improved.
Time, I suppose, will tell.
========================== JHR ==============================
From: Rick - DJ0IP / NJ0IP<Rick@DJ0IP.de>
I think MFJ recently came out with one that can handle high power,
but I haven't seen it yet and don't know how much it costs.
===============================================================
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