MFJ 956: any good?

MFJ 956: any good?

Post by Mr. Del » Tue, 24 Feb 2004 22:15:24

I ordered a preselector MFJ-956 from Universal Radio.
Please, give me any info about it, if I have to mod it and so on...
Thanks!
 
 
 

MFJ 956: any good?

Post by Piratebil » Tue, 24 Feb 2004 23:05:19



> I ordered a preselector MFJ-956 from Universal Radio.
> Please, give me any info about it, if I have to mod it and so on...
> Thanks!

The 956 is a fair little tuner after you fix it.

Unless they have done a major remod on the thing in the last 6 months
its got the same ***the 100 watt MFJ tuners have in em....The Variable
will look like its been stepped on after being dropped on the shop floor
and you will have to do a lot of straightening to get it to stop
shorting out.I found a couple of junk box caps and an inductor for 10$
at a hamfest and built a much better tuner

I tossed mine in the trash after two months.I couldnt bear selling it on
ebay and screwing someone else.

 
 
 

MFJ 956: any good?

Post by Ron Hardi » Tue, 24 Feb 2004 23:38:38


> I ordered a preselector MFJ-956 from Universal Radio.
> Please, give me any info about it, if I have to mod it and so on...
> Thanks!

I have three of them on various antennas before they go into wideband
amplifiers, to cut out intermodulation from overload.  They seem to
work okay.  Also useful for an external antenna on a portable
that doesn't have great dynamic range, for the same reason.

They cost you signal but cost you more from signals you
don't want, which is their point.

I don't know that they're a generally useful thing to have around.

If you have a receiver with great dynamic range there's no point to them.
In effect it's its own preselector.
--
Ron Hardin

On the internet, nobody knows you're a jerk.

 
 
 

MFJ 956: any good?

Post by Davi » Tue, 24 Feb 2004 23:43:50

Unless you need a preselector for a radio with a broadband front-end
(like on a Lowe HF-150)  or a single conversion receiver you'll notice
no improvement whatsoever.

In fact, there is some insertion loss.

On Mon, 23 Feb 2004 14:15:24 +0100, "Mr. Dell"


>I ordered a preselector MFJ-956 from Universal Radio.
>Please, give me any info about it, if I have to mod it and so on...
>Thanks!

 
 
 

MFJ 956: any good?

Post by RH » Wed, 25 Feb 2004 06:36:40



> I ordered a preselector MFJ-956 from Universal Radio.
> Please, give me any info about it,
> if I have to mod it and so on...
> Thanks!

.
Mr Dell,
.
There have been several posting on this Newsgroup (NG) regarding
the MFJ-956; that you may wish to take a look at.  

Here is the 'process' to Retrieve the Information:  
In the Search Input Block - Enter "MFJ-956"
Check-Off:  "Search only in Rec.Radio.Shortwave"
Click-On the "Google Search" Button.

Look for this Message Topic:
"MFJ-956 - Any Good?"  (View Thread 13 Articles)

iane ~ RHF
.
.

Subject: Re: MFJ-956 - Any Good?
Newsgroups: rec.radio.shortwave
Date: 2002-10-01 06:54:44 PST

CW,

I took a look at your link for the MFJ-956 Tuner Enhancement (Modification).

MFJ-956-MOD=> www.kc7nod.20m.com
Click-On [MFJ956] in the Left-Side Column.

The MOD looks interesting and well worth the effort for the
improvement achieved in the MFJ-956.

If you 'add' the Original text from Frank's posting to this NG it
would help to clarify the nature and extent of the MOD.

=QUOTE=

Subject: MFJ-956 Tuner Enhancement
Newsgroups: rec.radio.shortwave
Date: 2001-01-29 16:03:51 PST

For those of you using the MFJ-956 Tuner and a long wire who
are not entirely satisfied with its performance, here is a mod
that will improve its shortwave performance w.r.t. intermod
and effective tuning Q.  As designed the tuner works OK for
the longwave band but at higher freqs. (> 2MHz) the series
resonant tuner becomes problematic because the impedance of
the series L/C approaches the input and/or output impedances
and the Q is so poor its performance is marginal to none
depending on the length of the antenna used and its overall
configuration. The existing bandswitch is a double-pole,
six position with only one of the sections being used so one
can take advantage of the other section to switch in some
additional inductors that modify the antenna's input impedance.  
You will need to get a 1 uH, a 6.8 uH, and a 100 uH RF ***
(Mouser Electronics and probably Radio Shack in one of their
"grab bags"). The values aren't critical but should be within
20% or so.

The "RECEIVER" and "ANTENNA" (input and output) ports will
have to be reversed also so the tuning cap is on the output
(rcvr) side.  

Further improvement can be made on the LW range by changing
the 2.5 mH ***to a 4.7, 5,  or 6.8 mH choke.  This will
extend the lower end down to the specified 150 kHz for
antennas less than 100 feet.

If you are interested in this mod please E-mail me and
I will send the schematic to you.

Frank
=UN-QUOTE=

A Search of this NG for MFJ + 956 + MOD yeilded the above post.
(Sorry NG Links are to long and truncatable.)

~ RHF



> Frank K3YAZ is the man that came up with the modification.
> There was quite an interest in it and he was emailing the
> plans to people so I posted it to take the load off him.
> I don't own one off these units and haven't done the mod.
> I suppose he won't mind me posting his email address.

> He would be the one to talk to.
> --

> CW
> KC7NOD
> Web Page:  www.kc7nod.20m.com



> > Hi, folks - anyone have any experience with the MFJ-1956 tuner?  
> > Is it a winner or otherwise?  I notice CW has a mod on his webpage
> > - can CW or someone tell us what improvement that mod makes?

> > Thanks in advance for any input...

> > Bruce Jensen

.
 
 
 

MFJ 956: any good?

Post by CW » Wed, 25 Feb 2004 08:34:25

There is a modification on my website for this unit that is supposed to
greatly improve it. It was contributed by K3YAZ. I have never owned one of
these so have not done it myself.
http://www.kc7nod.20m.com/


Quote:> I ordered a preselector MFJ-956 from Universal Radio.
> Please, give me any info about it, if I have to mod it and so on...
> Thanks!

 
 
 

MFJ 956: any good?

Post by WShoot » Thu, 26 Feb 2004 15:03:24

I've never been too impressed with anything MJF put out.

Bill, K5BY

 
 
 

MFJ 956: any good?

Post by RH » Fri, 27 Feb 2004 06:51:53

MR. Dell,

Also take a look at the Grove Mini TUN-3 'used' on eBay.

~ RHF
.
.



> > I ordered a preselector MFJ-956 from Universal Radio.
> > Please, give me any info about it,
> > if I have to mod it and so on...
> > Thanks!

> .
> Mr Dell,
> .
> There have been several posting on this Newsgroup (NG) regarding
> the MFJ-956; that you may wish to take a look at.  

> Here is the 'process' to Retrieve the Information:  
> In the Search Input Block - Enter "MFJ-956"
> Check-Off:  "Search only in Rec.Radio.Shortwave"
> Click-On the "Google Search" Button.

> Look for this Message Topic:
> "MFJ-956 - Any Good?"  (View Thread 13 Articles)

> iane ~ RHF
> .
> .

> Subject: Re: MFJ-956 - Any Good?
> Newsgroups: rec.radio.shortwave
> Date: 2002-10-01 06:54:44 PST

> CW,

> I took a look at your link for the MFJ-956 Tuner Enhancement (Modification).

> MFJ-956-MOD=> www.kc7nod.20m.com
> Click-On [MFJ956] in the Left-Side Column.

> The MOD looks interesting and well worth the effort for the
> improvement achieved in the MFJ-956.

> If you 'add' the Original text from Frank's posting to this NG it
> would help to clarify the nature and extent of the MOD.

> =QUOTE=

> Subject: MFJ-956 Tuner Enhancement
> Newsgroups: rec.radio.shortwave
> Date: 2001-01-29 16:03:51 PST

> For those of you using the MFJ-956 Tuner and a long wire who
> are not entirely satisfied with its performance, here is a mod
> that will improve its shortwave performance w.r.t. intermod
> and effective tuning Q.  As designed the tuner works OK for
> the longwave band but at higher freqs. (> 2MHz) the series
> resonant tuner becomes problematic because the impedance of
> the series L/C approaches the input and/or output impedances
> and the Q is so poor its performance is marginal to none
> depending on the length of the antenna used and its overall
> configuration. The existing bandswitch is a double-pole,
> six position with only one of the sections being used so one
> can take advantage of the other section to switch in some
> additional inductors that modify the antenna's input impedance.  
> You will need to get a 1 uH, a 6.8 uH, and a 100 uH RF ***
> (Mouser Electronics and probably Radio Shack in one of their
> "grab bags"). The values aren't critical but should be within
> 20% or so.

> The "RECEIVER" and "ANTENNA" (input and output) ports will
> have to be reversed also so the tuning cap is on the output
> (rcvr) side.  

> Further improvement can be made on the LW range by changing
> the 2.5 mH ***to a 4.7, 5,  or 6.8 mH choke.  This will
> extend the lower end down to the specified 150 kHz for
> antennas less than 100 feet.

> If you are interested in this mod please E-mail me and
> I will send the schematic to you.

> Frank
> =UN-QUOTE=

> A Search of this NG for MFJ + 956 + MOD yeilded the above post.
> (Sorry NG Links are to long and truncatable.)

> ~ RHF



> > Frank K3YAZ is the man that came up with the modification.
> > There was quite an interest in it and he was emailing the
> > plans to people so I posted it to take the load off him.
> > I don't own one off these units and haven't done the mod.
> > I suppose he won't mind me posting his email address.

> > He would be the one to talk to.
> > --

> > CW
> > KC7NOD
> > Web Page:  www.kc7nod.20m.com



> > > Hi, folks - anyone have any experience with the MFJ-1956 tuner?  
> > > Is it a winner or otherwise?  I notice CW has a mod on his webpage
> > > - can CW or someone tell us what improvement that mod makes?

> > > Thanks in advance for any input...

> > > Bruce Jensen

> .

 
 
 

MFJ 956: any good?

Post by Mr. Del » Sat, 28 Feb 2004 02:57:43

RHF ha scritto:

Quote:> Also take a look at the Grove Mini TUN-3 'used' on eBay.

I can't found here at the moment on eBay.
Thanks