Mizuho MX7

Hi Addict Fellows!

I found something interesting today while I was browsing the net. I found a Japanese company manufacturing QRP rigs, which unfortunately closed down in 2004. It was Mizuho. Am SM0??? guy wrote about it, that he bought is from an SM1 friend and he enjoys QRP with that. Sorry, but I can not recall his callsign, neither can find the web-site again…
I tried to browse previous notes but found only a few notes regarding Mizuho QRP rigs, and all of them were regarding the 0,2W 144 MHz version, the MX-2. :frowning: I am interested in the MX7 7 MHz version. Anybody has a sample? Andbody has experiences? I am also interested in the P and FX series as well. Anybody has any comparison between them? Are these still available at the flea-markets? At what price?
It looks nice for me… Maybe it were worth to rebuild one during the long winter evenings while we miss activators. :slight_smile:
Of course I am interested especially in schematic diagrams. I failed 3-4 times downloading the .PDF files at Mizuho website. (Schematic diagram, manual, etc.) Can anybody help?

73 Jóska, HA5CW

In reply to HA5CW:Szia Jóska

OK1RP nek van kapcsolási rajza.


In reply to HA7UL:
Tnx Feri!
73: J.

Hi Joska,

I’m not quite sure if Feri has sorted it for
you now as I don’t speak Hungarian!

The MX-7S Schematic and Manual are available
from Mods DK, and certainly download ok.

I have the 2M version which as you say puts out
0.2 watts, but I believe the output from the HF
models is 1 or 2 watts.

The Mizuho models were also sold under the JIM
label, so look out for these too.

I have downloaded the manual and schematic for the
MX-7S, so if you still have problems, you could email
me (my email address is on QRZ.com), and I would
send a reply with the pdf’s attached.

Kind regards

Dave G0ELJ

In reply to G0ELJ:

My MX-14 (20m version) used to give 2W. I acquired it with a view to SOTA use but it was so absolutely mint I couldn’t bring myself to possibly scratch or mark it or get it wet. So I sold it to another collector at a very healthy mark-up.


I had a mizuho MX50 handheld SSB rig for 50mhz that I bought in Japan in 1979 it was crystal controlled on TX and had a VXO receiver that gave a limited receive tune.
I worked Hawaii on it!, but we were alongside in Honolulu at the time (I was R/O on QE2) The RX was very sensitive.

Phil G3YPQ

In reply to G3YPQ:

Sorry for going off topic for a moment.

Hi Phil,

I wonder if it was you at the /MM end of the first cave to ship contact via amateur radio back in the mid 1990’s? This was bewteen QE2 & a special event station for the Cave Rescue Organisation at White scar cave near Ingleton & the callsign was along the lines of GB2CRO. QE2 was off the grand banks near Newfoundland at the time when you called in on 20m.

I was operating the surface station on 20m at the time while the VLF cave radios were re-charging, but we arranged a sched for 20 minutes later once the VLF to HF relay was up & running again. It was quite difficult as the audible tone being used to switch the relay was not being notched out properly & at one point I dashed from the surface station to the cave station several hundred feet inside the cave to be another pair of ears for the operators underground.

I recently met up with Peter G3UCA who I am sure was operating the cave radio at the time & that contact is still talked about fondly to this day :slight_smile:

If that was indeed yourslef at the /MM end, please drop me an email so we can continue this conversation off the reflector if you wish, my email address is on qrz.com.

Of course, if this was not you, please ignore the above :wink:

Apologies to all for going off topic there.

Back to the subject, I looked at the 80m & 40m versions of this radio when first licensed & the only thing that put me off was that they are cw only. I was nowhere near confident enough at cw back then to spend money on a radio that only gave a couple of Watts on a single band, using a mode I was not very good at. In all other respects they are a fine little radio & would be ideal for SOTA.

I remember seeing a review in a UK amateur radio magazine, either Radcom, Practical Wireless, or Ham Radio Today of one of these radios, quite likely the 40m model, so if there is a archive of those magazines from the mid 1990’s it may be worth hunting down that review.

I seem to remember it as beibng quite favourable.


Mark G0VOF

Hi Mark,

I’m not sure which models you saw, but all
the MX series handhelds are SSB/CW to the
best of my knowledge.

Kind regards

Dave G0ELJ

In reply to G0ELJ:

You may well be right Dave, I am relying on my memory, which does have its limitations. HI!


Mark G0VOF

In reply to G0VOF:
Hello Mark and other SPOTA fan friends!

First of all: I am back from 9A land (specifically Sveti Filip i Jakob (JN73RX) where I celebrated my 1 year SOTA acticity :slight_smile: … without any RIG… :-((((

Mark G0VOF : CW is THE operation mode, the rest are supplementary options! :-))))) (Maybe, I’m a bit CW-blind? :wink: )

Dave, G0ELJ : You are right. Probably the early samples could only work in CW but the later ones are suitable for both SSB and CW. Also thanks for your kind assistance, but I have already downloaded MX7S and DC7S manuals/schematics and I noticed immediately that these are of very different complexiry versions, so I will download other versions P7DX to see, which can be reproduced … I see the weak point of these MIZUHO constructions: they demand an antenna tuner to a random length wire :frowning: as the easiest solution for activators.

Though the best solution were unambiguously finding a one at a flea market… (Lazy men’s soolution.)

73: Jóska, HA5CW

Hi Joska and others,
if you are interresting in Mizuho schematics or other informations then do not hesitate to email me. I have almost everything about Mizuho radios which was available on internet downloaded already in my PC :wink:
Mainly MX series…

Regarding the SOTA setup I am using MX radios with manual tuner with built-in SWR bridge designed by KD1JV in Altoids box and it works like champ. It is best setup I found ever… In case of whip antenna used the tuner is not needed.

73 - Petr, ok1rp

Posting this Japanese website http://homepage3.nifty.com/kaki-p/radio/mizuho.html It has the Japanese manuals (w/ schematics of course) of all the Mizuho MX series (with the amps and other peripherals that were options).

I botched my first SOTA activation a few weeks back. I had the power supply switch to CHARGE while transmitting. During normal operations this switch must be in the BATT possition. My MX-6S is just putting out 500mW with 8x NiMH AAs.

72, Mela

Joska and Feri,

Try to visit www.mizuhoradios.blogspot.com
where I am trying to put together all info about Mizuhos…
If you still need some schematic Joska then drop me an email.

73 - Petr, OK1RP

Mizuho blog updated. Another schematics available as same as troubleshooting articles over there.
73 - Petr, OK1RP