I need some crystal infomation for the 8719 pll chip

[dss56]

I know i can do the pll mod but I'm doing an experiment with the listed below.

I was able to get some xtals these frequencies
11.1758mhz 40 below
11.4758mhz 40 above
11.6258mhz 80 above channel 1

I tried the xtals in a washington base that has the 8719pll and the 11.3258 xtal
Have them on a electronic switch board so no oscillation just switched electronically to switch in each xtal including the 11.3258 stock xtal the switch board works great.

Here is the problem
the 11.3258 in slot 1 works as it should I can center it with the trimmer that is on the sw/board.
the problem with the other 3 xtals is I can get all center slot with the board trimmers for AM.

I cant get the xtals to work for SSB/usb/lsb they are way off. switch to am dead center.

Would anyone know how the xtals should of been cut what specs.

this was taken from info I found on the net.
FREQUENCY xx.xxxx
:
As desired.
ACCURACY
:
.005% or better.
HOLDER TYPE
:
HC18/U or HC49/U with solder leads.
CRYSTAL
CUT Fundamental up to about 20MHz. Crystals which are
being multiplied in the radio
should be specified as such. (For
example, the 11.325 MHz
crystal used in the
Cobra 148/2000GTL chassis is a tripler cut type.)
LOAD CAPACITANCE 10pF (series) preferred for easy adjustment. The 32 pF used in
many CB oscillators can be hard to set by the trimmer alone.

Would anyone know what is the correct info needed for the 11.3258 xtal and the above to be cut by a xtal company. The ones like I said i received will tune on AM but will not on SSB.

using this new xtal 11.4758 gives 27.415-27.815

If I centered the xtal with the trimmer to say 27.4850 ch 48 and switch to lsb it should be 27.4835 or USB 27.4865 or close to it. It will not tune to ssb it is like 27.4853 for lsb and 27.4858 for usb.



So what should I tell the xtal company to the info to cut the xtals at? If someone knows?

thanks

 

[OldTech03]

What are you using to test the frequency of the crystals in SSB mode another words what is the method by which you measure those frequencies? Also, do those numbers change with each crystal, for instance, are you seeing the same narrow amount of change with each crystal? Hope that makes sense. And of course, have done a proper alignment under the influence of each crystal? Also does the clarifier function on both receive and transmit.

 

[dss56]

OldTech3

Here is the switch board can add up to 6 xtals and works great as I have used this in the past for other radios so its not the switch board

Using 3 different freq-counters inline and in circuit at the correct test points.
the radio is all set with the 11.3258 proper xtal and I have not tried to tune the newer xtal in the radio as it would throw off the correct AM/USB freq using the 11.3258.

So I installed the newer 11.4758 xtal tuned the trim cap on the switch board to dead AM center 27.4850 then try ssb and not tuned. SSB should tune correctly but won't.

Im using a washington base radio with ssb. Like I said I can trim the xtal on the switch board or I directly removed the 11.3258 xtal and soldered the xtal to the radio board and same results no ssb tuning.

Its almost like still being on center Am with a tone into the mic, I switch back to the original 11.3258 xtal and 40 regular channels and AM/SSb is good.

Also have 3 xtal checkers and readers and the new xtals are deal on frequency.


Yes the clarifier is open with the 11.3258 xtal it will slide up 2kc and down about 3.

So I'm thinking the xtals were not cut correctly. If it was going to be used for just am its would be ok but SSB will not tune to usb/lsb.

I'm using xtals from example B the 11.475 just to try and have encountered this problem.

Also like I mentioned I had a xtal for extra channels from back in the days and put it in the board and directly in radio and worked I can trim to center AM and SSB would also work. But not the newer xtals I ordered

Hope the above info helped

EXAMPLE A

: Cobra 140/142GTL Uniden chassis. This uses an 11.1125 MHz tripler crystal. New crystals might be 10.9625 for the lower 40, 11.2625 for the high 40, and 11.4125 MHz for the high high 40 channels. For 10 Meters, use 11.5575 MHz (28.300 to 28.740 MHz) or 11.4575 MHz (28.000 to 28.440 MHz) depending upon your need for the USB or CW/USB parts of the band.

EXAMPLE B

: Cobra 148/2000GTL, Uniden GRANT/MADISON chassis. The existing crystal is a tripler,11.325MHz. New crystals would be 11.175 for the lower 40, 11.475 for the high 40, and 11.625 MHz for the high high 40 channels. For 10M, use 11.770 or 11.670 for USB or CW/USB respectively; coverage as shown above.

 

[OldTech03]

I struggled with how to present the case for the crystals not responding to a shift in capacitance and I wondering if indeed you have even harmonic crystals rather than true overtones. It could speak to the problem of little movement in a (+/-) way based on the amount of capacitance available in that circuit if the crystal isn't moving it most likely is a product of the crystal cut. You may try to introduce more capacitance in the form of a variable but that may not produce suitable results either. There may be others that can shed more light on this I'm struggling to bring to the surface all my education from a time when my memory young and full of promise. I truly have forgot more than I ever knew: LOL which could leave me with a negative?

 

[dss56]

This is the spec sheet the crystals were made crystals were made to.

 

[dss56]

There is no swing when I change to usb/lsb almost like staying on center AM.

Here is a spec sheet the 11.3258 crystals are made that work for the 8719 pll chassis when this is in the switch board it will center and also swing to the ssb offsets

 

[OldTech03]

There is no swing when I change to usb/lsb almost like staying on center AM.

Here is a spec sheet the 11.3258 crystals are made that work for the 8719 pll chassis when this is in the switch board it will center and also swing to the ssb offsets View attachment 27697

I would suggest you need the other crystals cut as this chart suggests for the 3258 crystal you would want them to function at their 3rd overtone where the specs of the first chart are not of a cut that facilitates that.

 

[dss56]

The crystal I got are ok i guess fro AM but like you said not cut to 3rd overtone.

thanks for the suggestion

 

[dss56]

OldTech03

Where on the chart did you read 3rd overtone? I did not see it.

thanks

 

[W2EKG]

Wouldn't a lesscom board be more stable?

 

[OldTech03]

OldTech03

Where on the chart did you read 3rd overtone? I did not see it.

thanks

Well it doesn't actually say 3rd overtone but in the oscillator circuit used in the Washington and other radios of that design the circuits, the crystals are more or less forced to function at a 3 overtone or 3rd harmonic level which pretty much would make the 11.3258 nominal frequency of the crystal on the second chart a better fit for that use. as it forces this crystal to run more freely at 34Mhz. which would be it's 3rd harmonic.

 

[dss56]

Im not on that path this is an experiment im working on and need to get the crystals cut correctly to work in ssb mode. So Trying to get correct info for the xtals. Years ago most Xtal CO's made the xtals for CB/Ham radios now its hard to find them most bit the dust gone out of business. I'll keep searching until I find a xtal co that can get them cut correctly

 

[OldTech03]

Wouldn't a lesscom board be more stable?

I would agree, that would be a more effective way to get what he is trying to do.

 

[dss56]

In this text I guess the tripler circuit cut is the same as the 3rd overtone correct me if im wrong.

HC18/U or HC49/U with solder leads.
CRYSTAL
CUT Fundamental up to about 20MHz. Crystals which are
being multiplied in the radio
should be specified as such. (For
example, the 11.325 MHz
crystal used in the
Cobra 148/2000GTL chassis is a tripler cut type.) Also use the 11.3258 xtal

 

[dss56]

I can do the the pll mod but im working on a experiment and need the correct crystals cut to work AM/SSB so im sure the 3rd overtone cut is what I need.

thanks