XRef - 10MHz-Locked Reference Oscillator

[VK6OX]

Excellent Dave....look fwd to getting hold of one (maybe two) with the 2nd to suit the TS590s which uses the same reference osc.

[VK5PJ]

Hello David Et all,
I guess I should have asked this question earlier, I have a number of IC-x75 series ICOM mono band radios, all use a 30.72 MHz reference. I have installed the CR64 TXCO option into most of them but still see a fair degree of long term stability issues.

Would 30.72MHz be an achievable output for the XREF board? I know these are an old radio and there may not be much demand for them so I am not holding out too much hope for it.

Regards,
Peter, vk5pj

[VK3HZ]

Hi Peter,

You're not the first to ask, so they are on the list.

Regards,
Dave.

[VK2OMD]

The TS-2000 is next in line, followed closely by the FT-847 (both being rigs that I own!)

Regards,
Dave.

It is my understanding that the clock used for the DSP in the TS2000 is not derived from the master clock, and will contribute some residual error to frequency even if the master clock was exactly on frequency.

Will your TS2000 module address that issue in the TS2000 design, or will it just supply a high accuracy master clock.

Owen

[VK3HZ]

As the name implies, the XRef replaces the Reference Oscillator which, in my experience, is the largest source of frequency error.

With a radio there may be several other sources of frequency error - carrier crystals, DDS setting accuracy and, in the case of the TS-2000, the sampling clock in the SDR-like 12kHz IF. This problem also arises for Digital modes where the PC soundcard sampling clock and internal processing can give significant freq errors.

I can feel a GippsTech Presentation coming on.

Regards,
Dave.

[VK3OE]

Hello Dave,

Great device, well done.
The next trick about the phase noise is to measure the sensitivity of a rig such as the 910 with the XRef and without. If there is any issue with the phase noise then this will easily show up as a decrease in sensitivity especially on 1296.

Looking forwrad to your result.

73
Andrew
VK3OE/VK3OER

[VK3HZ]

Hi Andrew,

While I don't really have the gear to measure sensitivity, we did carry out some rough tests on the FT-817 and noticed no difference in sensitivity between the original oscillator and the XRef.

To add to that, I'm just doing final tests on the TS-2000X version, installed in my own radio. The Mt Gambier 2m beacon is extremely weak here at the moment - just detectable by ear. I've switched back and forth from the standard oscillator to the XRef with 10 MHz feed, and there is no discernible difference in sensitivity. I've also listened to the Geelong beacon which is S9+40dB and I can't tell any difference as I tune back and forth over the signal (i.e. phase noise).

Regards,
Dave.

[VK3XDK]

We could possibly arrange a "hear down to -??? dbm" test using my signal generator but I doubt weather it will tell us anything we don't already know.
Performance has been as good or better in all? cases.

Could it also be the case in most transceivers that there is other noise (ie DDS noise) that far outweighs oscillator phase noise when it is this low??

[VK3HZ]

We've completed testing of the XRef Versatile installed in a Kenwood TS-2000 (X) and a Yaesu FT-847 and they are now available for purchase.

The recommended version for the TS-2000 is the XRef-VS with onboard power switching. This falls back to the radio's own reference oscillator when the external 10 MHz reference is not connected.

For the FT-847, the XRef-VT with onboard TCXO is recommended. This completely replaces the radio's own reference oscillator with the TCXO used when the external 10 MHz reference is not connected.

More details are here: http://www.vk3hz.net/XRef/XRef_Home.html

If you are interested in the XRef Versatile, please contact me directly at xref@vk3hz.net

Regards,
David Smith
VK3HZ

[VK3HZ]

Some photos of the installations

For the TS-2000, the XRef is mounted on top of the radio's own reference TCXO. It could also be mounted at the front of the radio.

XRef TS-2000 Installation

For the FT-847, the XRef is mounted behind the front panel.

XRef FT-847 Installation

[VK2LK]

Hi Guys,

Is there any chance of a version that works with Icom IC-7000 and 7600 series radios? This would be very handy as the standard frequency ref in the IC7000 seems to drift a bit.

Cheers,
Matt

[VK3HZ]

Hi Matt,

The IC-7000 is a bit of a problem. It uses an odd reference frequency of 24.8064 MHz which is difficult to generate cleanly with a PLL-based synthesiser. Still thinking about that one.

Conversely, the IC-7600 uses a neat 32.0 MHz reference frequency which the XRef can generate. However, looking at the Service Manual, the Reference Oscillator is enclosed in a metal can, soldered to the PLL board. Modification looks to be very difficult.

Regards,
Dave.

[VK2LK]

Thanks for that Dave,

Seem that ICOM really don't want people using external references with these radios, I guess de-soldering oscillator cans is getting quite fiddly and risky, especially on such an expensive rig..

Cheers,
Matt

[VK2OMD]

Hi Matt,

The IC-7000 is a bit of a problem. It uses an odd reference frequency of 24.8064 MHz which is difficult to generate cleanly with a PLL-based synthesiser. Still thinking about that one.

I think you are using a Si4133. It seems to me that you could set the PD to 3200Hz and be in range of the R and N dividers... but such a low PD freq is not good.

Owen

[VK3HZ]

Unfortunately, the minimum PD for the Si4133 is 10kHz.

Regards,
Dave.

[VK2LK]

Just on that same note as before, I believe the IC7000 also has its internal reference in a metal can soldered to the PCB also.

Sigh....

Cheers,
Matt

[VK5KX]

I have installed my X-Ref in the FT-817ND, I used an SMA feedthru and some semi-rigid for the job

Peter (vk5kx)

[VK2JDS]

Hi David , are you bringing some along to Gippstech? I am after a xref VS for my 910 and I'm sure there will be others after some too.
73 from Dave

[VK3HZ]

Hi Dave,

Yes, I'll have a handful of the different versions with me.

Regards,
Dave.

[VK4UH]

Hi all
I recently discovered an issue with my x-ref enabled TS2000x while out portable on a microwave activity day.

Without the external 10MHz reference connected the internal reference was not starting reliably. Once given 10MHz the radio worked fine and continued to do so even when reference was removed??

I was running on battery so supply voltage would have been below 13.8v of course

Has anyone else encountered this issue?

Beware out portable