Crystals for David Looser Modulator
 

I have a David Looser modulator on Ch 1 which I need to find crystals for to convert to channel 3. Anyone know who does wire ended ones to specified frequencies? All the ones I can find are Surface Mount types. Thanks

Re: Crystals for David Looser Modulator
 

I've used this company in the (distant) past and found them very helpful.

IQD Frequency Products Ltd, Station Road, Crewkerne, Somerset TA18 8AR

01460 270200

Quartz Crystals

Regards,

Tony.

Re: Crystals for David Looser Modulator
 

What with the high price of Crystals nowadays, I would modify the surface mount Crystal to fit, at least you can get them, that in itself is a miracle in recent years.
:beer:

Re: Crystals for David Looser Modulator
 

What frequency do you need, and with what tolerance?

Re: Crystals for David Looser Modulator
 

Hi Julian. 56.75 and 53.25Mhz. The absolute tolerance does not need to be too precise though I guess the spacing of 3.5 MHz is more critical. Thanks Tony. I have looked at !QD, they seem to do only surface mount. I may have to go that way. This is all for a recently acquiredd Murphy V310 fitted with 3 and 11 coils. Alternatively if anyone has any Ch1 or 9 coils they want to sell/swop, that would sort it.

Re: Crystals for David Looser Modulator
 

I guess 56.75 and 53.25Mhz implies overtone operation of lower-frequency crystals, whether the third or fifth would depend on the circuit.

You may find it cheaper to use a couple of the modern 'programmable oscillators'

for example https://uk.rs-online.com/web/p/progr...lators/5062205

or

https://www5.epsondevice.com/en/prod...r/sg81_91.html

and perhaps adapt the existing oscillator circuits to operate as buffers/triplers/quintuplers as needed.

Re: Crystals for David Looser Modulator
 

Steve, the link I posted contains some non-SMDs.

Here's one of them.

Tony.

Re: Crystals for David Looser Modulator
 

Thanks Tony and G6. The programmable oscillators look fun to play with. I will probably opt though for the crystals> Help much appreciated.

Re: Crystals for David Looser Modulator
 

Hello.

I was wondering about the suitability of crystal oscillator modules as opposed to just using a crystal.

The XTAL oscillator modules produce a square wave output and are commonly used in digital circuits for a clock signal. The Band 1 VHF modulator would normally use a crystal or LC resonator for the required frequency. These are sine wave oscillators.

Using an oscillator module for the vision and sound carrier could well be problematic due to all the harmonics associated with a square wave.

OT, but related to clock oscillator modules, I saw an interesting project for a RF Inductance Meter that uses crystal oscillator modules for the RF test frequency. A suitably selected capacitor on the output tames the dominant harmonics. The project was by N5ESE and can be found here: https://www.n5ese.com/l-meter.htm

Regards,
Symon

Re: Crystals for David Looser Modulator
 

OP. Are you wanting to source these two crystals?
Let me know and I will take a look.
The 53 one is a high band rx crystal (fc, -10.7, ÷3) and the 56 one a high band tx frequency crystal. (fc ÷ 3) as used in pmr, around 170MHz ish.
Rob

Re: Crystals for David Looser Modulator
 

Sorry, can't help with those frequencies. If anyone is interested, I have a bag of reclaimed 50.000MHz units in the UM1 enclosure

Re: Crystals for David Looser Modulator
 

Yes, I was wondering about harmonics on square wave, but probably tameable. If you think you might have them Robin, I would be very grateful. Thanks

Re: Crystals for David Looser Modulator
 

Be careful. The 'programmable crystal oscillators contain a phase locked loop with programmable dividers and a VCO.

On-silicon resonators for VCOs are rather limited in the Q they can achieve and this means that the overall phase noise performance they can achieve is much poorer than a straight-forward crystal oscillator alone.

All the counters ackling away on the same die aren't perfectly isolated, so a variety of spurs can be found on the output.

On the plus side, for each different frequency a manufacturer makes for the actual crystal oscillator inside the programmable oscillator package, they can sell them as a large number of frequencies within reach of the VCO's range and the choice of N/M ratios.

Be especially careful because numerous oscillator families in supplier data sheets are now programmable ones. The data sheets often fail to mention thatyou are not getting a simple crystal oscillator.

For noise-critical RF applications, it can be a bit of a devil looking through all the oscillators in stock at a distributor, wondering which ones are quiet.

David

Re: Crystals for David Looser Modulator
 

Hi,have you tried a VFO instead of the crystals.I did this with the same modulator 20 years ago with good results.

Re: Crystals for David Looser Modulator
 

Hi
I managed to obtain crystals last year for the Rod Pentode Channel 1 Modulator from Vince Jakomin, sadly they were the last of his stock and no more were being made, there is now only one company (allegedly) in Europe making crystals and they are expensive. There are companies in China though and they offer fast turn around which is to be avoided as crystals have an aging process and if not done will drift so avoid these people if you want an accurate crystal. I also have a David Looser board here that refuses to work even with new crystals and I'm beginning to think the PCB must be porous and conductive, I've tried everything.

Re: Crystals for David Looser Modulator
 

Hi to all,
Hi Niechcial Steve,

In 2021 i helped a french chap acquire one-of special crystals to repair a vintage transceiver.
I went through a friend residing in Japan.

The company is ARROW-DENSHI, Japan, here is their web site via Google Translate :

https://www-arrow--jp-com.translate....en&_x_tr_hl=en

They are in the crystal business since decades & know all about aging, etc.
Prices were very reasonable, less than 7000 Yen for 3x special cut crystals (all different Fr) & postage to EU.
Worked A-OK as soon as installed, user was pleased.
There is an inquiry form on the website.

My friend is aged and i can't ask him to be a middleman again.

Hope this can help,

Best Regards
jhalphen
Paris/France

Photos of the crystals & invoice.

Re: Crystals for David Looser Modulator
 

Seconded here - have used IQD many times in the past.

Are AEL still in business?

Re: Crystals for David Looser Modulator
 

Thanks for all the help on this folks

Re: Crystals for David Looser Modulator
 

Hi there, I've got an old V410 tuner - I dont know what coils are in it but if they are any good to you, I'll have a look.
Dave

Re: Crystals for David Looser Modulator
 

I've tried to contact this company with no success.
Not called but contacted by email.