Quartz crystals.

[G1RAO keith]

Decided to power up my old B44 which still works but is on 70.26 MHz the old AM frequency are there any places I can order xtals for 70.362 the new calling frequency (yes I know the cost of new crystals will be more than the set is worth ) hoping the cost is not sky high. Keith.

[John M0GLN]

I've bought crystals from Vincent Jakomin in the past.

vincentvoy@hotmail.co.uk

He used to have a small ad in the Practical Wireless every month but I've not read a PW for quite a time now.

John

[G1RAO keith]

Hi John.

Just looked at the latest RSGB band plan 2021 and it still says 70.26 is the AM calling frequency. I thought I had seen somewhere that it had moved to 70.362
But that frequency or thereabouts is an Internet gateway? Maybe I don't need new xtals . Still confused. Regards, Keith.

[SiriusHardware]

Can I ask why that new frequency 70.3620? was chosen?

There are a few old synthesised low band AM radios (ie, Pye / Philips MX293) which would easily go to 70.3625 so it seems almost perverse not to have picked a 12.5Khz step to make the use of such radios easier.

What about a DDS (Direct Digital Synthesis) chip, I am sure someone makes one on a wee board with DIP switches to select frequency. If not a quick Arduino programme will do the job and has been written already. First hit https://create.arduino.cc/projecthub...-ad9850-09ea6f the board is already made as is the code, just stick in a constant instead of the knob twiddle bit. An Arduino nano will be more than sufficient and costs a couple of quid. Just noticed it goes up to 40MHz, I bet there is a higher frequency version. Or chuck a frequency doubler on the output.

[Jon_G4MDC]

Not moving from 70.26MHz. Dream on who ever thought of that.

70.2625 can be hit with most modern junk. Near enough.

It's empty anyway!

[SiriusHardware]

On a short (10 minute) look around I could not find a single reference to a new 4 metre AM calling frequency of 70.362. Maybe this is a locally adopted convention?

Why was the original .260 chosen? A big batch of surplus crystals available somewhere?

[SiriusHardware]

I think those cheap DDS things have been examined in some detail here, if I remember, the problem was that the output was not very pure.

[Restoration73]

As I understood it, B44 tx crystal was fc/6 somewhere in 11 MHz. Whereas the Pye W15
was just fc/2.

[Jon_G4MDC]

Use it or lose it.
70.26 AM is much too quiet.

I tried some time ago with an Echolink node (whatever you might think of that) MB7AM at Amersham but it suffered an antenna fault very early on.

It was good while it lasted. Modern rules with H&S and working on towers mean it is just about impossible to fix it now. I hope to get the gear back soon but what use is it?

Have Whitehalls, Cambridges, Westminsters, F30AMs, Bantams, P5001s, and maybe more crystalled up. And later added M293, MX293 and a Marconi AM Fire Brigade set and and the FM/AM Plod one - I forget the numbers - hey I'm an ex Pye man after all!

And there is exactly who to work with them? No-one.

[G1RAO keith]

So it seems 70.260 IS the AM calling frequency according to the RSGB 2021 band plan so no need to obtain new crystals. Where it got the idea it had moved I don't know. 70.3625 is one of the Internet gateway frequencies. The band plan also says 70.260 is used for FM calling as well as 70.450. I also have two vintage PYE reporters on 70.260 so if no one replies to my CQ I can talk to my self on the reporter what fun!

[Jon_G4MDC]

Hello Keith. I wish you well.
Actually I reckon your post has turned up something else apart from Quartz crystals.

I reckon it should perhaps be moved to Vintage Amateur and Military.

Further I propose that 70.26 AM activity could become a sticky.
(Mods please? It's not quite 405 lines is back on Band 1 but it has a parallel - yes/no?)

[G1RAO keith]

Hi Jon
I. Agree there is something about am it takes me back years ,(well to the 60,s ) listening to amature am signals on my CR 100 I like using older gear I have just got my 19 set running and using that on the VMARS am net (3.615) .the B44 mk iii is only nominal 2W connected to a vertical 1/2 wave end fed, been out in the garden today setting it up,don't know if you have one but I bought a nano VNA H4 an excellent piece of test gear for checking swr / reactance/ return loss ,and a smith chart reading.regards Keith.

[Jon_G4MDC]

Good for you!

The VNA matter I'll save for another post but let's hope the 70.26AM cause will be given a boost!

I see the thread has moved already! (Thanks)

My original plan with the Echolink node was to establish one in the South, then maybe someone might try in the North..and so on?

If not far enough apart it will interfere and it won't work.

[SiriusHardware]

...two vintage PYE reporters on 70.260 so if no one replies to my CQ I can talk to myself on the reporter

Traditionally, the last-ditch way to get some activity going on a band you are interested is to have two radios which work on it and give (or loan) one of them to your mate. That way you get at least one person to talk to.

[SiriusHardware]

I must be one of the few who don't wax nostalgic for A.M as a communications (as opposed to broadcast) mode, - there has always been a similar debate in CB circles (but I don't want to divert this down that road) - A.M. has always sounded rather mellow and soft and it has an inherent tendency to sound proportionally quieter once the station you are listening to is more than 'x' distance away - (when closer in, the receiver AGC action comes into play).

I much prefer hard, crisp FM for comms. Sounds exactly the same at any signal strength between S3 and 30-over, and below S3 just gets gradually more noisy.

One thing about A.M, it's a much simpler mode to demodulate (just add a diode and capacitor) so making homebrew A.M. receivers has always been inherently easier than making homebrew FM receivers, at least before F.M. demodulators-on-a-chip came along.

[ortek_service]

I got a one-off crystal made for around £8 in 2-3weeks by IQD in the 80's, but whilst still going no doubt it would be much more expensive these days. It seems virtually all crystal manufacture is now done in the far-east - even custom ones (with varying quality and very long lead times).

Other crystal manufacturers that I recall used to do custom crystals are Golledge, HyQ, QuartzLab, Euroquartz, Total Freq. Control (TFC), Webster.
But many probably have a fairly high Min Qty / Order value, as well as long lead-times.

However there are other solutions these days, from single-chip PLL's (with built in VCO),
Or miniature One-time programmable oscillations components with this all integrated inside. You can order these from some distributors who will program to your requested frequency, or do some yourself (Abracon / Discera - Now Microsemi) but need to use their programmer + software. Although the upper frequency may be limited to 50MHz etc (Presumably 70MHz crystal was an overtone, so might be able to tune to harmonics if using a square-wwave oscallator)

[G8BBZ]

Hi All,
Just in case it is of use to somebody, there is a crystal manufacturer in the Czech Republic who will do one off crystals and are not too expensive.
KRYSTALY, Hradec Králové, a.s.

http://www.krystaly.cz

I believe this is the company who make the crystals sold on the VMARS forum.
cheers
Peter G8BBZ

[SiriusHardware]

QuartzLab

A quick aside, the correct spelling is Quartslab - using that spelling may make them easier to find on the 'net. It's a riff on Quartz Slab, I guess.

[Jon_G4MDC]

I am fighting myself about putting an Si5351 +PIC + display in a mint FM10D Pye Cambridge for 10m that I have.

I could very easily do it, except then it would be a complete historical wreck. It would get "all the channels"...

Should I buy it some crystals for 29.6 and leave it at that? I have conflicting thoughts about it.