Mizuho / Jim MX14S QRP transceiver- crystals

[SiriusHardware]

Can anyone point me to a definitive list of the original Mizuho / Jim part numbers for the VXO crystals for this venerable 2 Watt 14Mhz / 20m band QRP transceiver?

They were originally produced in the early eighties but were produced under several different brand names for quite a few years afterwards. There is a nice website which explains a lot about them here:-

http://www.mizuhoradio.com/mx.html

-but it lacks information about the crystals.

[Radio Wrangler]

The Mizuho radios (and the Totsuko VHF ones) used some crystals with quite remarkable pullability. This translates into quite small electrode areas yet still good activity.

You could try talking to some of the crystal manufacturers who were active in that era. They will have had requests and might have a recipe. Golledge Crystals is still on the go as a firm, though sadly Peter golledge iis no longer with us. I think Quartzlab are still on the go too.

They were effective little radios, and the 2 metre ones were exceptional.

David

[SiriusHardware]

Putting together bits and pieces from the net I'm now able to answer my own question - the part numbers for the crystals for the whole MX series have the form

fX - nnS

Where 'f' is the frequency of the band (Mhz) and 'nn' are the Khz hundreds and tens digits of the beginning of the 50Khz frequency segment covered by the crystal, ie,

14X - 00S = 14.000MHz to 14.050MHz
14X - 05S = 14.050MHz to 14.100MHz
14X - 10S = 14.100MHz to 14.150MHz
14X - 15S = 14.150MHz to 14.200MHz

..and so on. As it turns out one of the original UK stockists of the range still has small stocks of some, sadly not all, of the VXO crystals used by the MX range even though the radios have long been out of production.

I took it out for a run in the car tonight with an 8ft long monoband Valor PRO-AM 20m aerial on a magmount (the car was not moving, of course!). Away from the colossal man-made interference which ruins my HF reception at home, reception was lovely and I worked into Russia (on SSB) without trying too hard. People are always surprised (indeed, sometimes don't really believe me) when I say I'm using 2W.

What I like about these Mizuho / Jim radios is their simplicity: They are completely analogue, so they sound very clean. Tuning requires surgically precise fingers since the main TX/RX tuning control covering 50Khz is just a 180 degree tuning capacitor without any reduction gear.

I did also hear another QRP operator who said he was using 5W SSB, probably from an FT-817, but he was not the 'owner' of the frequency I heard him on and I lost him when he tuned away to find his own frequency.

[SiriusHardware]

Originally Posted by Radio Wrangler

The Mizuho radios (and the Totsuko VHF ones) used some crystals with quite remarkable pullability. This translates into quite small electrode areas yet still good activity.

I have a Mizuho SB-2M in my collection as well.

I worked some very long distances using it and a 2-element beam from my favourite Northumbrian hilltop. I always felt, though, that the other stations were doing all the heavy lifting - putting out more power to reach me and straining harder to hear me. The only thing I was able to contribute to the contact was my height ASL.

While I was hunting for anyone who might have some crystals I saw a lot of stuff saying that the Mizuho crystals were particularly 'bendy' ones which other crystal manufacturers might find hard to reproduce the characteristics of. As mentioned in another post, one original dealer still has a few of (some, only) of the crystals for the MX range.

[Radio Wrangler]

One member of the Dunfermline club, David Birch, GM1EHK, used an SB-2M from a hilltop home in Lochgelly in the 1980s. I think he used a 7 element J-beam. What was surprising was that he could work from Fife right down into the midlands without there being a 'lift' on.

David GM4ZNX

[SiriusHardware]

You probably won't know what happened to that radio?

I acquired my SB-2M from the Bring and Buy at the Galashiels rally some time in the mid 1990s, so there is a slim possibility that my example is the very radio you're thinking of.

[Radio Wrangler]

Less slim than you may think. I believe it was sold around that time as a silent key clearance, and there weren't many around. Gala is one of the few rallies in Scotland.

I had the Totsuko TB2100 which was the same system, but with a 10W PEP PA.

David

[SiriusHardware]

I've just remembered that I used to get to Kelso as well (This was at the height of my initial enthusiasm for amateur radio, so I regularly went to nearly every 'local' rally including those over the border. But it definitely came from either Kelso or Galashiels).

If it is that particular Mizuho SB-2M, I'm sorry to hear that the owner is no longer with us: But I hope he would be glad to know it is still looked after and appreciated.

Although (like all of my amateur gear) it is used less often now than it was, it did some sterling service in many of the Practical Wireless VHF-QRP contests - we never competed seriously but we did it just for the enjoyment of hearing 2m SSB crackling with life. We worked contacts as far away as the south coast (from Northumbrian hilltops) on occasion.

[Radio Wrangler]

I miss the Kelso rally in the Tait hall. It was a good cross-border meeting and allowed the junk to circulate over a wider area. As I went to all of them, we have probably bumped past each other in the long-thin bring and buy room.

I understand Quartslab are on the go again. They more than anyone might have done crystals inthe past for the Japanese VXO rigs, so they may still know the recipe. I was involved in the exact opposite sort of quatrz, ultra-low pullability and ultra-low phase noise that went into some HP gear.

David

[SiriusHardware]

I currently have crystals (for the MX-14S) for 14.000-14.050, 14.050-14.100 and 14.200-14.250. The first two would be fine if I were any good at CW - I passed the 12WPM morse test and then let it slump badly, so what I really need is a crystal for the 14.250-14.300Mhz portion of the band which includes the telephony 'QRP centre of activity' that I can't get to on it at the moment.

Just searched for QSL's website on your suggestion and Mizuho is one of the brands / makes for which they 'hold specifications', so I've sent an email off to them requesting details. They also seem to have a 'no order is too small' policy which sounds promising.

[Biggles]

You could also try Vincent Jakomin at I Q Electronic Design. I have had one off xtal specials made by him and the service has always been very good. He still advertises in PW magazine as far as I know.
Alan.

[SiriusHardware]

Biggles, thanks for the alternative suggestion: I've had a conversation with QSL, who say they are sure they can do them and have quoted a decent price.

They've asked me to send them one of the original Mizuho crystals for non destructive / non-invasive analysis so they can be sure the new ones will be a good match. I've agreed to do so. Hopefully that will mean that anyone else who needs MX14 crystals in the future will just be able to order them.

[Radio Wrangler]

That sounds good!

There's a thread running on the group about a CRT with a sticker saying "Repaired by Cathodeon"

Cathodeon were also about the best of the British quartz crystal manufacturers, and in addition to crystals, they made a pi-network crystal test fixture (Just add freq reference, synthesiser and an HP vector voltmeter) Thee fixtures are still used today and are easily recognised as looking like a gold plated brick with three piano keys on the top.

It's probable that your old crystal has an appointment with one of these.

David

[gm0ekm cecil]

In the the 1980's I had ad a remarkable ssb contact. I would need to check the log book to confirm the date time etc. I'm very chufffed to say that I broke into a qso with a station in the Channel Islands who was working a station in Western Australia on 20m. The VK station came back to my call. We had a 15 minute qso with q5 two way contact on my Mitzuho 20m. 2 watt qrp hand held tranceiver, my antenna which was approx. 75 metres from my qth. The aerial was on top of my tower at 50' and it was only an ex 1/2 wave CB whip which worked quite well on 20M. and my radio was the Trio hybrid tranceiver TS820S, which is still giving yeomen service.

[SiriusHardware]

That sounds like -serious- QRP, using a decent antenna at what, in most real-world amateur stations, would be an exceptional height above ground. I can't claim to have done so well, but then I can only ever operate HF QRP portable or mobile because of the overwhelming noise which emanates from the properties around me. My normal setup with the Mizuho is two handy trees / two soft weights / nylon cord and a simple half-wave dipole held up with all of the foregoing, or as mentioned previously, a monoband mobile whip for the band.

All my contacts on the Mizuho have been inter-European, but I've never had the correct crystal to cover the 20m telephony QRP 'centre of activity', hence my original query.

Two new crystals are in the process of being made for me by by QSL - it'll be interesting to see how well they compare with the tuning range and linearity of the original Mizuho crystals.