JD1BMH on MX-21S worked from central EU...what a DX !

Jul, OK1SP worked JD1BMH using my Mizuho, MX-21S handheld transceiver by amazing Mr.Takada, JA1AMH. 

Output power: 1.9W 

Band: 21MHz 

Antenna: 5el. beam at 30m (yes, it helped a lot) NB: OFF 

Powered: inside AA size battery cells 

Key: RM-31 Czech military key (1961) 

Setup simplified, so no CW-2S unit used for T/R switching and side tone with CW keying. 

Watch this amazing QSO here:

https://youtu.be/TGVvi-i-m-M?si=ivGkTo-p8WoYGgzd

73 - Petr, OK1RP
--
B: http://goo.gl/Fd2JhJ
What could be easier..?  ¯‍∖‍_‍(‍ツ‍)‍_‍/‍¯

The real power output of MX-21S measured...!

Hello all,

as I read several articles about the Mizuho MX-xxS series radios where owners doubt about its real RF output power and some of them measured (no explained how and what test equipment has been used in their case) the power at around 1W only instead of 2W specification I decided to measure one of my own MX-21S radios.

I arranged the test equipment which consisting the BNC-N adapter > N-N cable > R&S NAS Directional Power Meter calibrated by National Metrology Authority, CMI > N-N cable > Palstar, DL2K dummy load.

BNC-N adapter: 0.02dB attenuation at 50MHz

N-N cable: 0.06dB attenuation at 50MHz

Total attenuation inserted: 0.08dB

Battery powered MX-21S / Ubat: 8.4V

Measured power

Xtal A / 21.025MHz: 1.9W

Xtal B / 21.225MHz: 1.9W

Combined uncertainty: +/-5% calculated for k=2

So total RF power output including the inserted attenuation at the test setup is 1.9 x 1.018 = 1.935W (0.08dB total attenuation converted to power ratio)

MX-21S total RF power output measured at 8.4V Ubat: 1.935W +/- 80mW

73 - Petr, OK1RP

Mizuho KX-2 Sky coupler - manual translation guide

Hi all,

if someone has this Sky coupler KX-2 in collection or even using it on the air maybe some short translation guide can be useful...

Input impedance 50-600 ohms
Optional Z-2 loop antenna for AM BC band


DESCRIPTION

The KX-2 Sky Coupler. This tuner is intended for shortwave and broadcast listening only, but it will safely handle up to about 10W of power without arcing over, so it is suitable for QRP use.

An optional Z-2 loop antenna for broadcast listening was available. There appear to be several versions of the KX-2. Some have just terminal screws for input and output and gaping holes where an SO-239 connector might be added. This is the configuration shown in the Japanese manual. At least some had SO-239 connectors factory installed similar to the later KX-3 model.

In addition, some have rack mount handles while others do not. Once again, construction is first class.

Specifications:
Frequency Range: 0.5-30 MHz
Maximum through power: 10W
Input impedance: 50-600 ohms
Dimensions: 220x66x154mm


Hope it help,

73 - Petr, OK1RP

Simple PSK31/SSTV interface for Mizuho radios

 

Hi all,

 

 

today I am coming with simple PSK31/SSTV interface which  can be also used with all of our Mizuho radios.

 

The external speaker is already available as same as PTT. The rest of sigs needed is necessary to wiring out from the MX radios. 

 

 

 

Is there someone who will test it on the air?


73 - Petr, OK1RP
.../-.-

Rare Mizuho / Lowe MX-6 QRP Transceiver on eBay !

Rare Mizuho / Lowe MX-6 QRP Transceiver - with original 4M (70Mhz) conversion is on eBay:

 

https://www.ebay.com/itm/Rare-Mizuho-Lowe-MX-6-QRP-Transceiver-with-original-4M-70Mhz-conversion/254346316858?hash=item3b3838cc3a:g:QFIAAOSwSmJdanXC

73 Petr, OK1RP

Look at the MX-2 by Roger, G3XBM

Hi all,

there is nice article about the Mizuho MX-2, 2m SSB/CW handy transceiver writen by Roger, G3XBM.
The MX-2 was a small, handheld SSB transceiver for 2m VHF operation. By modern standards it was a small brick but it worked very well, apart from its low battery life. Similar units were made for HF bands...

https://sites.google.com/site/g3xbmqrp3/vuhf/mx2

Nice to read and at the end you will find the link for short video...


73 - Petr, OK1RP

An actual eBay Mizuho sales (22Nov2017)

Hi all,

an actual eBay Mizuho sales (22Nov2017):

https://www.ebay.com/itm/MIZUHO-CB-Radio-LOT-amp-mic-mizuho-PL6-PL15-NICE-ESTATE-FIND-rare-vintage-/162760807804


https://www.ebay.com/itm/qrp-ham-radio-hf-ssb-cw-mizuho-walkie-talkie-portable-transceiver-10-meter-mx28s/202114196792


https://www.ebay.com/itm/Mizuho-SX-3-Preselector-Filter-Tuner-Ham-Radio-Rare/172925406856?hash=item2843284e88:g:5tIAAOSwEzFZ4SnP


https://www.ebay.com/itm/MIZUHO-28-S-10-METER-RADIO-CRYSTAL-13-55817-Mhz-FOR-29-400-MADE-BY-JAN-CRYSTAL/311988660786?hash=item48a3f92a32:g:68QAAOSw2s1UuAqb


https://www.ebay.com/itm/qrp-ham-radio-hf-ssb-cw-mizuho-walkie-talkie-portable-transceiver-40-meter-mx7s/202114196353


73 - Petr, OK1RP

Mizuho MS-1 microphone wiring for MX-serie radios

Hi all,

as some of friends asked me which kind of microphone will work with MX series of Mizuho transceivers and which kind of microphones used Mizuhos originally there I am sharing what I know about it.

For external Mic. need to be inserted the 3.5mm diameter jack plug. See the picture which is available in original manual including the points (6) and (7) regarding the external microphone and external speaker usage.

The microphone connection wiring is diferent from the MX-3.5S and MS-1 external speaker/microphone should be used.

There is the schematic diagram of the MS-1 speaker/ext. microphone made by Mizuho.

The MS-1 won't work with the older radios like MX-2, MX-6, MX-10Z, and MX-15 handheld SSB/CW transceivers because the microphone plug wiring is different than on the later Pico MX-series handhelds.

The another external speaker/microphone M-4 model by Mizuho should be used.

The 40mm diameter, 8Ohms, 0,35W speaker is used in MS-1 and the 600Ohms Mic line. The microphone plug and external speaker plug are integrated into molded common connector which is the difference from the M-4 btw. The PTT switch only connects and disconnects one wire.

Hope it helps,

73 - Petr, OK1RP

The Mizuho PL-15 amplifier driven by MX-21S...?

Hi all,

an interesting question came last days from John, W8BCR regarding the PL-15...

"So I have an mx-21s radio. I have a line on a pl-15 model amp. Are these compatible? Or do I have to find a pl-21 model amp? Any info would be helpful! Thanks, John W8BCR"

The PL-15 is dedicated for MX-15 transceiver from Pico series. (together with VX-15 ext. VFO) This amplifier is designed for 300mW exciter as the MX-15 radio has this power output level.

The PL-21S is dedicated for MX-21S transceivers and it is driven by them at 2W power level.

Both amplifiers are using the same transistors but in different

conditions... Your PL-15 is using 3dB attenuator in the input and 1Ohms resistor to the final 2SC1945 base...

while PL-21S is using 6dB attenuator in the input and 3Ohms at the base of 2SC1945.

The rest of the amps is same...

So in order to avoid over-driving the PA by PL-21S radio or damage the transistor you should change the components inside or if you would not like to do anything inside of the PA (to keep it collectible)then I propose to try use the external RF attenuator in the input of the PL-15 to jump your exciting power from MX-21S handheld down to approx. 300mW.

The best way is to measure the real power output from your MX-21S into dummy load (I am expecting something around 1.5W out) and then make an appropriate attenuator to get 300mW output for your PL-15 amplifier.

The rest of the both amps is same including the cables so I am confident it should work for you.

Hope it help,


73 - Petr, OK1RP

DX Handy 10m does not transmit on SSB... hints for debugging

Hello,

one of the issue which can happends on the Mizuho handies is lack of SSB TX as reported by John, W8BCR...

"Ok, so I confirmed my dx handy 10 meter receives, and I confirmed with another radio that it transmits CW. It does not seem to transmit voice. When I push in the PTT, I hear a quick static noise accompanied with a flash of the transmit light but it does not remain on while I hold the PTT in. At this point I can use the built in keyer and transmit CW, but no voice. Any ideas where to start? Thanks, John W8BCR

There are the hints and tips from our family members as follows:

Likewise i have a couple and both obtained cheap as faulty and not receiving. Both had the same problem which is that due to the weight of the xtal filter and its soldered connection on the pcb if the radio is dropped then the filter breaks away at the solder joint and hey presto NO REC.
quick solder job and back in business again .
Cheers
Roy
GM4VKI

Hi, I have a collection of nineteen (19) MX radio's , most problems I have encountered have been due to dirty slide switches, especially the SSB/CW change over, blast them with switch cleaner and rattle them up and down until your arm aches.
Peter G0KOK

More details about this troubleshooting you can find on Mizuho and Nishi Musen Reflector by Caitlyn, K9NI over here:
https://groups.yahoo.com/neo/groups/mizuhoradio/conversations/messages/1471

Hope it helps to more owners,

73 - Petr, OK1RP