OT: Looking for schematic and troubleshooting info on MFJ-223 VNA

[wayne burdick]

My MFJ-223 VNA took a dive (cause unknown). The SWR readings are very high regardless of load.

Has anyone found a schematic for this thing? The manual also mentions an MCU reset switch, but I'm guessing that's outdated. No such switch.

tnx
Wayne
N6KR

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[Keith N6JPA]

On Thu, 22 Aug 2019 16:11:37 -0700, you wrote:

>My MFJ-223 VNA took a dive (cause unknown). The SWR readings are very high regardless of load.
>
>Has anyone found a schematic for this thing? The manual also mentions an MCU reset switch, but I'm guessing that's outdated. No such switch.
>
>tnx
>Wayne
>N6KR
>

Contact the MFJ support at their web site they may have a schematic
they can send you.
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[Gary K9GS]

I have one of these and I'd be interested in what you find out. Did you transmit into it by mistake?I'm pretty sure MFJ doesn't manufacture these but I would contact their customer service and see what they say.73,Gary K9GS
-------- Original message --------From: Wayne Burdick <[hidden email]> Date: 8/22/19  6:11 PM  (GMT-06:00) To: Elecraft Reflector <[hidden email]> Subject: [Elecraft] OT: Looking for schematic and troubleshooting info on
  MFJ-223 VNA My MFJ-223 VNA took a dive (cause unknown). The SWR readings are very high regardless of load. Has anyone found a schematic for this thing? The manual also mentions an MCU reset switch, but I'm guessing that's outdated. No such switch.tnxWayneN6KR______________________________________________________________Elecraft mailing listHome: http://mailman.qth.net/mailman/listinfo/elecraftHelp: http://mailman.qth.net/mmfaq.htmPost: mailto:[hidden email] list hosted by: http://www.qsl.netPlease help support this email list: http://www.qsl.net/donate.htmlMessage delivered to [hidden email]
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[wayne burdick]

I already did what they said they would do: open it up and look for any
parts that had come loose and resolder them. They don't build it and can't
do much in the way of troubleshooting. It's also out of warranty.l

Wayne


On Thu, Aug 22, 2019 at 5:01 PM Gary K9GS <[hidden email]> wrote:

> I have one of these and I'd be interested in what you find out. Did you
> transmit into it by mistake?I'm pretty sure MFJ doesn't manufacture these
> but I would contact their customer service and see what they say.73,Gary
> K9GS
> -------- Original message --------From: Wayne Burdick <[hidden email]>
> Date: 8/22/19  6:11 PM  (GMT-06:00) To: Elecraft Reflector <
> [hidden email]> Subject: [Elecraft] OT: Looking for schematic
> and troubleshooting info on
>         MFJ-223 VNA My MFJ-223 VNA took a dive (cause unknown). The SWR
> readings are very high regardless of load. Has anyone found a schematic for
> this thing? The manual also mentions an MCU reset switch, but I'm guessing
> that's outdated. No such
> switch.tnxWayneN6KR______________________________________________________________Elecraft
> mailing listHome: http://mailman.qth.net/mailman/listinfo/elecraftHelp:
> http://mailman.qth.net/mmfaq.htmPost: mailto:[hidden email]
> list hosted by: http://www.qsl.netPlease help support this email list:
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[Mark Goldberg]

I have no experience with that one, but a common failure of other small two
port VNAs is ESD blowing the RF switches at the ports. That is a one port
VNA, so I don't know if it even has switches.

What can it hurt to replace whatever part is closest to the connector?

I have a MiniVNA Tiny two port VNA and it works well, although dynamic
range could be better.

73,

Mark
W7MLG

On Thu, Aug 22, 2019, 5:11 PM Wayne Burdick <[hidden email]> wrote:

> I already did what they said they would do: open it up and look for any
> parts that had come loose and resolder them. They don't build it and can't
> do much in the way of troubleshooting. It's also out of warranty.l
>
> Wayne
>
>
> On Thu, Aug 22, 2019 at 5:01 PM Gary K9GS <[hidden email]> wrote:
>
> > I have one of these and I'd be interested in what you find out. Did you
> > transmit into it by mistake?I'm pretty sure MFJ doesn't manufacture these
> > but I would contact their customer service and see what they say.73,Gary
> > K9GS
> > -------- Original message --------From: Wayne Burdick <[hidden email]
> >
> > Date: 8/22/19  6:11 PM  (GMT-06:00) To: Elecraft Reflector <
> > [hidden email]> Subject: [Elecraft] OT: Looking for schematic
> > and troubleshooting info on
> >         MFJ-223 VNA My MFJ-223 VNA took a dive (cause unknown). The SWR
> > readings are very high regardless of load. Has anyone found a schematic
> for
> > this thing? The manual also mentions an MCU reset switch, but I'm
> guessing
> > that's outdated. No such
> >
> switch.tnxWayneN6KR______________________________________________________________Elecraft
> > mailing listHome: http://mailman.qth.net/mailman/listinfo/elecraftHelp:
> > http://mailman.qth.net/mmfaq.htmPost: mailto:
> [hidden email]
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[ke9uw]

I have an MFJ 226 and it seems fine. But a friend had that one too and opted to get a Rig Expert analyzer to replace it because he liked it better.
Might be a chance to try one if your MFJ is dead.

Jack BMW Motorcycles
Chuck KE9UW
[hidden email]

Sent from my iPad

> On Aug 22, 2019, at 7:10 PM, Wayne Burdick <[hidden email]> wrote:
>
> I already did what they said they would do: open it up and look for any
> parts that had come loose and resolder them. They don't build it and can't
> do much in the way of troubleshooting. It's also out of warranty.l
>
> Wayne
>
>
>> On Thu, Aug 22, 2019 at 5:01 PM Gary K9GS <[hidden email]> wrote:
>>
>> I have one of these and I'd be interested in what you find out. Did you
>> transmit into it by mistake?I'm pretty sure MFJ doesn't manufacture these
>> but I would contact their customer service and see what they say.73,Gary
>> K9GS
>> -------- Original message --------From: Wayne Burdick <[hidden email]>
>> Date: 8/22/19  6:11 PM  (GMT-06:00) To: Elecraft Reflector <
>> [hidden email]> Subject: [Elecraft] OT: Looking for schematic
>> and troubleshooting info on
>>        MFJ-223 VNA My MFJ-223 VNA took a dive (cause unknown). The SWR
>> readings are very high regardless of load. Has anyone found a schematic for
>> this thing? The manual also mentions an MCU reset switch, but I'm guessing
>> that's outdated. No such
>> switch.tnxWayneN6KR______________________________________________________________Elecraft
>> mailing listHome: http://mailman.qth.net/mailman/listinfo/elecraftHelp:
>> http://mailman.qth.net/mmfaq.htmPost: mailto:[hidden email]
>> list hosted by: http://www.qsl.netPlease help support this email list:
>> http://www.qsl.net/donate.htmlMessage delivered to [hidden email]
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>>
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[David Gilbert]

There is some pretty hilarious irony in that recommendation from MFJ.

That being said, is there any possibility to swap out the battery pack? 
If it just gave up the ghost on it's own (i.e., you didn't accidentally
blow the front end or something), that would be my first suspect for
something that might just suddenly fail on it's own.

73,
Dave   AB7E



On 8/22/2019 5:10 PM, Wayne Burdick wrote:
> I already did what they said they would do: open it up and look for any
> parts that had come loose and resolder them.
> Wayne
>

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[ANDY DURBIN]

BH7KVE seems to be the source.  That call is returned in several search results but is not list at QRZ.

73,
Andy, k3wyc
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