Date   

Re: ADF5355 - Good Enough for 24 GHz!

Paul G8KFW
 

Hi Brian

 

Thank you for putting the files on the reflector   we might have to start a file structure soon on the reflector

Please note I only received my first ADF 5355  4 days ago and haven’t fired it up yet but

Just one point the ADF 5355 I have has 2 inputs on the left hand side and 3 on the right hand side all in line 

so making at least 3 variants  available

regards Paul B


From: ukmicrowaves@... [mailto:ukmicrowaves@...]
Sent: 23 December 2017 17:18
To: ukmicrowaves@...
Subject: Re: [ukmicrowaves] Re: ADF5355 - Good Enough for 24 GHz!

 

 

The greenPCB at https://groups..yahoo.com/neo/groups/ukmicrowaves/files/ADF5355_Green_PCB.jpg  looks to be remarkably similar, although there are minor differences in screen print positions and some track widths.  At first sight, component references look to be the same.

 

'jnt

 

 

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On 23 December 2017 at 16:20, brian.flynn@... [ukmicrowaves] <ukmicrowaves@...> wrote:

 

Hi Paul,
Thanks for the suggestion of putting the files up on this reflector. For some reason that had not occured to me.
They are there now. Not sure how exactly the component values on the board follow the schematic though. the R values I can read in the loop filter on my one black specimen are different. I have also uploaded a HiRes photo of the PCB pinched from one of the Ebay adverts. I have found it useful (printed out on A4 ! ) when working on the PCB. I have not investigated the RF de-coupling of the board. The designer seems to have followed AD's recomendations there. The major departure was the the use of two LT "low noise" regulators as opposed to three of the AD "ultra low noise" parts recomended, one on each rail, AVDD, DVDD and VP5V. Incidentally the recommended part. the ADM7150 is 10 times lower noise than the LT part if the data sheet is to be beleived. I have now got some the will need a proper PCB to use them as the have the dreaded Pin 0 on the base of the package.

73s
Brian GM8BJF

 

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Re: Mutek WBFM board info

Tom GM8MJV
 

Mike,

Have uploaded the doc to the files area.

Apologies for some of the pages - dot matrix printer on yellow paper and kicking around for 20+ years does fade a little.

Any page you need re-scanned just ask.

Tom

On 23 Dec 2017, at 16:18, mike@pencoys.org.uk wrote:

yes Tom, the Solfan or equivilent heads, ex traffic light or similar.
Ok, there are far better systems available now. But none that can show how
relativly easy, and cheap, it is to get on the band. unless you know
different.


On 23 Dec 2017 at 13:06, Tom Melvin tom@tkrh.co.uk [ukmicrowaves] wrote:

Is that the old 1984 unit that used old intruder alarm heads? GOIF 107ub?

Tom
GM8MJV


On 23 Dec 2017, at 09:38, mike@pencoys.org.uk [ukmicrowaves]
<ukmicrowaves@yahoogroups.com> wrote:

Seasons wotzits, Nadelik Lowen, etc.

Has anyone got the paperwork for Chris' Mutek wbfm 10ghz board?.
any info appreciated.
thanks, Mike G8NXD/M3MSM


Re: ADF5355 - Good Enough for 24 GHz!

Andy G4JNT
 

The greenPCB at https://groups.yahoo.com/neo/groups/ukmicrowaves/files/ADF5355_Green_PCB.jpg  looks to be remarkably similar, although there are minor differences in screen print positions and some track widths.  At first sight, component references look to be the same.

'jnt


Virus-free. www.avg.com

On 23 December 2017 at 16:20, brian.flynn@... [ukmicrowaves] <ukmicrowaves@...> wrote:
 

Hi Paul,
Thanks for the suggestion of putting the files up on this reflector. For some reason that had not occured to me.
They are there now. Not sure how exactly the component values on the board follow the schematic though. the R values I can read in the loop filter on my one black specimen are different. I have also uploaded a HiRes photo of the PCB pinched from one of the Ebay adverts. I have found it useful (printed out on A4 ! ) when working on the PCB. I have not investigated the RF de-coupling of the board. The designer seems to have followed AD's recomendations there. The major departure was the the use of two LT "low noise" regulators as opposed to three of the AD "ultra low noise" parts recomended, one on each rail, AVDD, DVDD and VP5V. Incidentally the recommended part. the ADM7150 is 10 times lower noise than the LT part if the data sheet is to be beleived. I have now got some the will need a proper PCB to use them as the have the dreaded Pin 0 on the base of the package.

73s
Brian GM8BJF



Re: New file uploaded to ukmicrowaves

Andy G4JNT
 

... and I've just uploaded a photo of the Green PCB - after it's been modded for external input.

'Andy  G4JNT


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On 23 December 2017 at 16:22, <ukmicrowaves@...> wrote:
 

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the ukmicrowaves
group.

File : /ADF5355_Black_PCB.png
Uploaded by : gm8bjf <brian.flynn@...>
Description : Photo of black ADF5355 PCB.

You can access this file at the URL:
https://groups.yahoo.com/neo/groups/ukmicrowaves/files/ADF5355_Black_PCB.png

To learn more about file sharing for your group, please visit:
https://help.yahoo.com/kb/index?page=content&y=PROD_GRPS&locale=en_US&id=SLN15398

Regards,

gm8bjf <brian.flynn@...>



New file uploaded to ukmicrowaves

ukmicrowaves@...
 

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the ukmicrowaves
group.

File : /ADF5355_Green_PCB.jpg
Uploaded by : andy_jnt <andy.g4jnt@gmail.com>
Description : ADF5355 Green PCB

You can access this file at the URL:
https://groups.yahoo.com/neo/groups/ukmicrowaves/files/ADF5355_Green_PCB.jpg

To learn more about file sharing for your group, please visit:
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Regards,

andy_jnt <andy.g4jnt@gmail.com>


New file uploaded to ukmicrowaves

ukmicrowaves@...
 

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the ukmicrowaves
group.

File : /ADF5355_Black_PCB.png
Uploaded by : gm8bjf <brian.flynn@tiscali.co.uk>
Description : Photo of black ADF5355 PCB.

You can access this file at the URL:
https://groups.yahoo.com/neo/groups/ukmicrowaves/files/ADF5355_Black_PCB.png

To learn more about file sharing for your group, please visit:
https://help.yahoo.com/kb/index?page=content&y=PROD_GRPS&locale=en_US&id=SLN15398

Regards,

gm8bjf <brian.flynn@tiscali.co.uk>


Re: ADF5355 - Good Enough for 24 GHz!

Brian Flynn GM8BJF
 

Hi Paul,
Thanks for the suggestion of putting the files up on this reflector. For some reason that had not occured to me.
They are there now. Not sure how exactly the component values on the board follow the schematic though. the R values I can read in the loop filter on my one black specimen are different. I have also uploaded a HiRes photo of the PCB pinched from one of the Ebay adverts. I have found it useful (printed out on A4 ! ) when working on the PCB. I have not investigated the RF de-coupling of the board. The designer seems to have followed AD's recomendations there. The major departure was the the use of two LT "low noise" regulators as opposed to three of the AD "ultra low noise" parts recomended, one on each rail, AVDD, DVDD and VP5V. Incidentally the recommended part. the ADM7150 is 10 times lower noise than the LT part if the data sheet is to be beleived. I have now got some the will need a proper PCB to use them as the have the dreaded Pin 0 on the base of the package.

73s
Brian GM8BJF


New file uploaded to ukmicrowaves

ukmicrowaves@...
 

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the ukmicrowaves
group.

File : /ADF4351_schematic.pdf
Uploaded by : gm8bjf <brian.flynn@tiscali.co.uk>
Description : Circuit of the "black" Chinese ADF4351 PCB

You can access this file at the URL:
https://groups.yahoo.com/neo/groups/ukmicrowaves/files/ADF4351_schematic.pdf

To learn more about file sharing for your group, please visit:
https://help.yahoo.com/kb/index?page=content&y=PROD_GRPS&locale=en_US&id=SLN15398

Regards,

gm8bjf <brian.flynn@tiscali.co.uk>


New file uploaded to ukmicrowaves

ukmicrowaves@...
 

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the ukmicrowaves
group.

File : /ADF5355_schematic.pdf
Uploaded by : gm8bjf <brian.flynn@tiscali.co.uk>
Description : Circuit of "black" Chinese ADF5355 PCB

You can access this file at the URL:
https://groups.yahoo.com/neo/groups/ukmicrowaves/files/ADF5355_schematic.pdf

To learn more about file sharing for your group, please visit:
https://help.yahoo.com/kb/index?page=content&y=PROD_GRPS&locale=en_US&id=SLN15398

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Re: Mutek WBFM board info

Tom GM8MJV
 

Is that the old 1984 unit that used old intruder alarm heads?   GOIF 107ub?

Tom
GM8MJV


On 23 Dec 2017, at 09:38, mike@... [ukmicrowaves] <ukmicrowaves@...> wrote:

 

Seasons wotzits, Nadelik Lowen, etc.

Has anyone got the paperwork for Chris' Mutek wbfm 10ghz board?.
any info appreciated.
thanks, Mike G8NXD/M3MSM



Re: ADF5355 - Good Enough for 24 GHz!

Neil Smith G4DBN
 

I wondered about that as well, but the PTI XO5051 and Valpey-Fishers I am using have positive slope, so I didn't need to try it.

Beware of the cheap PTIs, I bought three from China, one was DOA, another only produced -11dBm, the other was perfect.  I did get a no-quibble refund though. The slightly more expensive ones liek item 252616031486 do state that they are tested before dispatch.

The Valpey-Fisher locks at 1.783V and has a +234Hz/V slope and makes +13dBm.  The good PTI puts out +21dBm and is spot on at 2.180V.

As Andy said before, for most practical uses, there is no need to lock these things, they stay very solidly on frequency. You could build one into an insulated box with a gel cell to keep it running, but the main influence I found was in the resistive divider.  I use a very good 22 turn Bourns 10K pot and two identical 4k7s from the ends to ground and the vref out, and the resistors are glued to each other and the case of the OCXO, as is the pot, then the whole lot is encased in a layer of soft foam and that is pressed into a carved cavity in a block of polystyrene.

Neil G4DBN



On 23/12/2017 09:08, Andy Talbot andy.g4jnt@... [ukmicrowaves] wrote:
 
OK How does this work ?

In the HMC1031 Data sheet, for VCOs with negative tuning slope it says   " ...  connect the loop filter AC ground to VCC instead of GND.."    Normally for -Ve slope VCOs you need to swap the pulse up and pulse down pins, or add an inverting amplifier.   How can changing the AC ground affect the tuning direction.



bypass story .. ADF5355 - Good Enough for 24 GHz!

F1CHF
 

I had a dream !
dream was to find a multi capacitor (100 nF, 10 nF and 1 µf for example)
in a UNIQUE package (SMD will be fine)
I have done some search without succes ...
 
nobody knows ?
 
Francois F1CHF
  
 
 
 
 
-------Message original-------
 
Date : 23/12/2017 11:22:13
Sujet : Re: [ukmicrowaves] Re: ADF5355 - Good Enough for 24 GHz!
 
 

And again its important to appreciate that any old ferrite bead won't
do! There are a large number of different internal geometries and
materials in use, and reference to data sheets is essential.

Many of the synthesisers have internal LDO regulators, and HF
decoupling, but others require multi-octave bypassing and you won't know
until you read the literature ... Too much decoupling is (usually!)
better than too little!

73

Chris

GW4DGU

--
Christopher Bartram MIET
Christopher Bartram RF Design
Llygad yr Haul
Carno
CAERSWS
Powys SY17 5LE

phone: 01686237732
mobile: 07545094490
email: cbartram@...
URL: www.christopherbartramrfdesign.com

Note: This message is for the addressee of this email only. It may contain confidential, proprietary,or legally priviledged information. Noconfidentiallity or privilege is waived or lost by any mistransmission. If you receive this message in error, please immediately delete it and all copies of it from your system, destroy any hard copies of it, and notify the sender. You must not, directly, or indirectly, use, disclose, distribute, print or copy anpart of this message if you are not the intended recipient Christopher Bartram RF Design reserves the right to monitor all email communications through its network. Any views expressed in this message are those of the individual sender, except where the message states otherwise and the sender is authorised to state them to be the views of any such entity.

 


Re: ADF5355 - Good Enough for 24 GHz!

Christopher Bartram <cbartram@...>
 

And again its important to appreciate that any old ferrite bead won't do! There are a large number of different internal geometries and materials in use, and reference to data sheets is essential.

Many of the synthesisers have internal LDO regulators, and HF decoupling, but others require multi-octave bypassing and you won't know until you read the literature ... Too much decoupling is (usually!) better than too little!

73

Chris

GW4DGU


--
Christopher Bartram MIET
Christopher Bartram RF Design
Llygad yr Haul
Carno
CAERSWS
Powys SY17 5LE

phone: 01686237732
mobile: 07545094490
email: cbartram@theiet.org
URL: www.christopherbartramrfdesign.com

Note: This message is for the addressee of this email only. It may contain confidential, proprietary,or legally priviledged information. Noconfidentiallity or privilege is waived or lost by any mistransmission. If you receive this message in error, please immediately delete it and all copies of it from your system, destroy any hard copies of it, and notify the sender. You must not, directly, or indirectly, use, disclose, distribute, print or copy anpart of this message if you are not the intended recipient Christopher Bartram RF Design reserves the right to monitor all email communications through its network. Any views expressed in this message are those of the individual sender, except where the message states otherwise and the sender is authorised to state them to be the views of any such entity.


Mutek WBFM board info

mike@...
 

Seasons wotzits, Nadelik Lowen, etc.

Has anyone got the paperwork for Chris' Mutek wbfm 10ghz board?.
any info appreciated.
thanks, Mike G8NXD/M3MSM


Re: ADF5355 - Good Enough for 24 GHz! [3 Attachments]

Andy G4JNT
 

OK How does this work ?

In the HMC1031 Data sheet, for VCOs with negative tuning slope it says   " ...  connect the loop filter AC ground to VCC instead of GND."    Normally for -Ve slope VCOs you need to swap the pulse up and pulse down pins, or add an inverting amplifier.   How can changing the AC ground affect the tuning direction.

Puzzled
'jnt

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On 23 December 2017 at 01:15, Neil neil@... [ukmicrowaves] <ukmicrowaves@...> wrote:
 
[Attachment(s) from Neil included below]

Hi Paul, happy to share the circuit for the 100MHz disciplined OCXO, I am doing a new version of the PCB (hopefully without the layout errors this time!) but it is simple enough to make using an SMD breakout board for the HMC1031 and use dead-bug construction for the rest.  I made a version using discrete high speed SMD logic, but the HMC1031 works just as well, with faster lock-up, and has a lower component count.


X1 in OCXO in, X6 is OCXO out, X2 is 10MHz in, X3 goes to the OCXO.  X5 is a lock indication LED, X4 is +12V in .

The 8613 op-amp is only required if your OCXO needs more than 2.4V at nominal frequency (my Valpey-Fisher locks at 1.74V, so I just jumper out the op amp). NM=not mounted.

The Ublox thing hardly needs a circuit. I just bought the LEA-M8F chip on a tiny PCB and wired it up to a PIC and OCXO.  If I can get the thing to work OK with the 100MHz OCXO, I'll write that up as well.

The 100MHz OCXOs I use were cheapish from ebay, and they are remarkably good standalone, although not in the same class as a Morion MV89.  My best Morion has been running for 11 months standalone, and has only drifted 3ppb relative to my GPSDO since then (currently 2.5Hz LF at 23cm) and most of that was in the first month.

For comparison, the discrete logic version looks like this:

The MC12080D is set to divide by 20. Half of  7474 is used as a /2 and the 7486 is the usual XOR.  X1 feeds the OCXO.  The LTC1719s are there to square up the 10MHz ref and the ECL output from  the 12080.

Board for this version looks like this:

Neil G4DBN


On 23/12/2017 00:15, 'Paul Bicknell' paul@... [ukmicrowaves] wrote:
 

Hi Neil

 

Thank you for your reply as this is a hot topic and most do not use a 50 or 100 Mhz reference I was wondering if you could Write up the cct and components used so all could benefit from your recherché

As I personally use 198 Khz  for my 10 mhz reference

 

Regards Paul


From: ukmicrowaves@... [mailto:ukmicrowaves@yahoogroups.com]
Sent: 22 December 2017 16:47
To: ukmicrowaves@...
Subject: Re: [ukmicrowaves] Re: ADF5355 - Good Enough for 24 GHz!

I use a decent 100MHz OCXO in a thermally isolated enclosure as the clock for my 5355s.  I phase lock the OCXO to my 10MHz Rb reference using a very very low bandwidth PLL with an HMC1031. That keeps the OCXO just about as clean as when it is free running, although it takes 10-15 minutes to settle completely. I use 47 microfarad ceramic SMD caps in the loop filter.

For /P use, I have a U-Blox LEA-M8F GPS chip and use that to discipline a 10MHz Morion OCXO directly, then use that to lock the 100MHz OCXO as at home.  I am trying some tests to see if I can get the LEA-M8F to lock a 100MHz OCXO directly, by dividing the output by five to give a 20MHz comparator frequency. 

I was rather alarmed at the noise performance of my ADF5355 boards, so Brian's work on this is very timely and welcome.  I was wondering about doing some micrsurgery and installing some 0402 caps near some of the supply pins to see if that helped, but I'll try the low-esr supply bypass caps first. I note that some of the other manufacturers recommend using SMD ferrite beads to bring the supply to the bypass caps as well as ultra-low noise regulators and use of multilayer boards to keep noise off the supply lines.

Neil G4DBN

On 22/12/2017 14:36, 'Paul Bicknell' paul@... [ukmicrowaves] wrote:

 

Hi Brian

Thank you for your posting so can I assume we need to use a 50 mhz  reference for lowest phase noise the problem is most of user have 10 mhz off air reference

I assume the  reference must be very clean for the best / lowest phase noise  _._,_.___


Posted by: Neil


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Re: ADF5355 - Good Enough for 24 GHz!

Andy G4JNT
 


The LMX2541  synth chip has six separate DC supply feeds into the chip, powering different parts of the Fract-N and PLL circuitry.  The data sheet specifies each one being fed via a separate choke with its own bypass capacitor.
A circuit of how that chip is used can be seen at http://www.g4jnt.com/LMX2541_Synth_Module.pdf.

My experience of that chip is that it generally has lower sidebands and spurious (shan't call it phase noise) than any of the AD equivalent products supplied on Chinese PCBs.     Quite how good the AD ones could be if decoupled to the same extent as the LMX device: who knows?

As an aside, my very first breadboard of the LMX2541, on a homebrew PCB, missed out one of those inductors, one feeding part of the logic circuitry.  But instead of the device not working at all, it generated wrong frequencies, and misbehaved in odd ways.  SO much so I thought I'd damaged it having reworked the mounting of just about every other component on the PCB.    It was only after playing with subsequent devices that I went back and revisited that board, found the missing inductor and all worked properly.


On 22 December 2017 at 16:47, Neil neil@... [ukmicrowaves] <ukmicrowaves@...> wrote:
 

 ..., but I'll try the low-esr supply bypass caps first. I note that some of the other manufacturers recommend using SMD ferrite beads to bring the supply to the bypass caps as well as ultra-low noise regulators and use of multilayer boards to keep noise off the supply lines.

Neil G4DBN



On 22/12/2017 14:36, 'Paul Bicknell' paul@... [ukmicrowaves] wrote:
 

Hi Brian

 

Thank you for your posting so can I assume we need to use a 50 mhz  reference for lowest phase noise the problem is most of user have 10 mhz off air reference

I assume the  reference must be very clean for the best / lowest phase noise

 




Virus-free. www.avg.com


Re: ADF5355 - Good Enough for 24 GHz!

Andy G4JNT
 

At rallies and roundtables I've often seen good quality TCXOs and OCXOs for sale at frequencies other than 10MHz that don't sell - simply because they are not 10MHz!  They are usually significantly cheaper and open to a haggle on price.    Some 13MHz OCXOs I bought were really very good.    Also seen large high quality TCXOs in the several tens of MHz region.    If such units have a voltage control input then they can be locked to a master reference one way or another.

OCXOs at VHF are around too and for most practical purposes, any OCXO is going to be stable and accurate enough for our purposes - there really is no need agt all to go to GPS stability for microwave operation.  the few parts in 10^-8 is more than adequate up to 24GHz even for the frequency accuracy needed for WSJT.

Using Fract-N synthesizers it doesn't matter what the actual value of reference frequency input is.

Andy  G4JNT


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On 23 December 2017 at 00:15, 'Paul Bicknell' paul@... [ukmicrowaves] <ukmicrowaves@...> wrote:
 

Hi Neil

 

Thank you for your reply as this is a hot topic and most do not use a 50 or 100 Mhz reference I was wondering if you could Write up the cct and components used so all could benefit from your recherché

As I personally use 198 Khz  for my 10 mhz reference

 

Regards Paul


From: ukmicrowaves@... [mailto:ukmicrowaves@yahoogroups.com]
Sent: 22 December 2017 16:47
To: ukmicrowaves@...
Subject: Re: [ukmicrowaves] Re: ADF5355 - Good Enough for 24 GHz!

I use a decent 100MHz OCXO in a thermally isolated enclosure as the clock for my 5355s.  I phase lock the OCXO to my 10MHz Rb reference using a very very low bandwidth PLL with an HMC1031. That keeps the OCXO just about as clean as when it is free running, although it takes 10-15 minutes to settle completely. I use 47 microfarad ceramic SMD caps in the loop filter.

For /P use, I have a U-Blox LEA-M8F GPS chip and use that to discipline a 10MHz Morion OCXO directly, then use that to lock the 100MHz OCXO as at home.  I am trying some tests to see if I can get the LEA-M8F to lock a 100MHz OCXO directly, by dividing the output by five to give a 20MHz comparator frequency. 

I was rather alarmed at the noise performance of my ADF5355 boards, so Brian's work on this is very timely and welcome.  I was wondering about doing some micrsurgery and installing some 0402 caps near some of the supply pins to see if that helped, but I'll try the low-esr supply bypass caps first. I note that some of the other manufacturers recommend using SMD ferrite beads to bring the supply to the bypass caps as well as ultra-low noise regulators and use of multilayer boards to keep noise off the supply lines.

Neil G4DBN

On 22/12/2017 14:36, 'Paul Bicknell' paul@... [ukmicrowaves] wrote:

 

Hi Brian

Thank you for your posting so can I assume we need to use a 50 mhz  reference for lowest phase noise the problem is most of user have 10 mhz off air reference

I assume the  reference must be very clean for the best / lowest phase noise  _._,_.___


Posted by: Neil <neil@...>


Reply via web post

Reply to sender

Reply to group

Start a New Topic

Messages in this topic (7)


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Re: ADF5355 - Good Enough for 24 GHz!

Neil Smith G4DBN
 

Hi Paul, happy to share the circuit for the 100MHz disciplined OCXO, I am doing a new version of the PCB (hopefully without the layout errors this time!) but it is simple enough to make using an SMD breakout board for the HMC1031 and use dead-bug construction for the rest. I made a version using discrete high speed SMD logic, but the HMC1031 works just as well, with faster lock-up, and has a lower component count.


X1 in OCXO in, X6 is OCXO out, X2 is 10MHz in, X3 goes to the OCXO. X5 is a lock indication LED, X4 is +12V in .

The 8613 op-amp is only required if your OCXO needs more than 2.4V at nominal frequency (my Valpey-Fisher locks at 1.74V, so I just jumper out the op amp). NM=not mounted.

The Ublox thing hardly needs a circuit. I just bought the LEA-M8F chip on a tiny PCB and wired it up to a PIC and OCXO. If I can get the thing to work OK with the 100MHz OCXO, I'll write that up as well.

The 100MHz OCXOs I use were cheapish from ebay, and they are remarkably good standalone, although not in the same class as a Morion MV89. My best Morion has been running for 11 months standalone, and has only drifted 3ppb relative to my GPSDO since then (currently 2.5Hz LF at 23cm) and most of that was in the first month.

For comparison, the discrete logic version looks like this:

The MC12080D is set to divide by 20. Half of 7474 is used as a /2 and the 7486 is the usual XOR. X1 feeds the OCXO. The LTC1719s are there to square up the 10MHz ref and the ECL output from the 12080.

Board for this version looks like this:

Neil G4DBN


On 23/12/2017 00:15, 'Paul Bicknell' paul@... [ukmicrowaves] wrote:

Hi Neil

Thank you for your reply as this is a hot topic and most do not use a 50 or 100 Mhz reference I was wondering if you could Write up the cct and components used so all could benefit from your recherch

As I personally use 198 Khz for my 10 mhz reference

Regards Paul


From: ukmicrowaves@... [mailto:ukmicrowaves@...]
Sent: 22 December 2017 16:47
To: ukmicrowaves@...
Subject: Re: [ukmicrowaves] Re: ADF5355 - Good Enough for 24 GHz!

I use a decent 100MHz OCXO in a thermally isolated enclosure as the clock for my 5355s. I phase lock the OCXO to my 10MHz Rb reference using a very very low bandwidth PLL with an HMC1031. That keeps the OCXO just about as clean as when it is free running, although it takes 10-15 minutes to settle completely. I use 47 microfarad ceramic SMD caps in the loop filter.

For /P use, I have a U-Blox LEA-M8F GPS chip and use that to discipline a 10MHz Morion OCXO directly, then use that to lock the 100MHz OCXO as at home. I am trying some tests to see if I can get the LEA-M8F to lock a 100MHz OCXO directly, by dividing the output by five to give a 20MHz comparator frequency.

I was rather alarmed at the noise performance of my ADF5355 boards, so Brian's work on this is very timely and welcome. I was wondering about doing some micrsurgery and installing some 0402 caps near some of the supply pins to see if that helped, but I'll try the low-esr supply bypass caps first. I note that some of the other manufacturers recommend using SMD ferrite beads to bring the supply to the bypass caps as well as ultra-low noise regulators and use of multilayer boards to keep noise off the supply lines.

Neil G4DBN

On 22/12/2017 14:36, 'Paul Bicknell' paul@... [ukmicrowaves] wrote:

Hi Brian

Thank you for your posting so can I assume we need to use a 50 mhz reference for lowest phase noise the problem is most of user have 10 mhz off air reference

I assume the reference must be very clean for the best / lowest phase noise _._,_.___


Posted by: Neil


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Re: ADF5355 - Good Enough for 24 GHz!

Paul G8KFW
 

Hi Neil

 

Thank you for your reply as this is a hot topic and most do not use a 50 or 100 Mhz reference I was wondering if you could Write up the cct and components used so all could benefit from your recherché

As I personally use 198 Khz  for my 10 mhz reference

 

Regards Paul


From: ukmicrowaves@... [mailto:ukmicrowaves@...]
Sent: 22 December 2017 16:47
To: ukmicrowaves@...
Subject: Re: [ukmicrowaves] Re: ADF5355 - Good Enough for 24 GHz!

I use a decent 100MHz OCXO in a thermally isolated enclosure as the clock for my 5355s.  I phase lock the OCXO to my 10MHz Rb reference using a very very low bandwidth PLL with an HMC1031. That keeps the OCXO just about as clean as when it is free running, although it takes 10-15 minutes to settle completely. I use 47 microfarad ceramic SMD caps in the loop filter.

For /P use, I have a U-Blox LEA-M8F GPS chip and use that to discipline a 10MHz Morion OCXO directly, then use that to lock the 100MHz OCXO as at home.  I am trying some tests to see if I can get the LEA-M8F to lock a 100MHz OCXO directly, by dividing the output by five to give a 20MHz comparator frequency. 

I was rather alarmed at the noise performance of my ADF5355 boards, so Brian's work on this is very timely and welcome.  I was wondering about doing some micrsurgery and installing some 0402 caps near some of the supply pins to see if that helped, but I'll try the low-esr supply bypass caps first. I note that some of the other manufacturers recommend using SMD ferrite beads to bring the supply to the bypass caps as well as ultra-low noise regulators and use of multilayer boards to keep noise off the supply lines.

Neil G4DBN

On 22/12/2017 14:36, 'Paul Bicknell' paul@... [ukmicrowaves] wrote:

 

Hi Brian

Thank you for your posting so can I assume we need to use a 50 mhz  reference for lowest phase noise the problem is most of user have 10 mhz off air reference

I assume the  reference must be very clean for the best / lowest phase noise  _._,_.___


Posted by: Neil


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Re: ADF5355 - Good Enough for 24 GHz!

Neil Smith G4DBN
 

I tried bashing the boards, and sat them on top of a speaker playing loud music and pure tones.  There was definitely a bit of microphony, I wasn't sure what the cause was, but I slathered the board with Araldite.  That seemed to help a lot.  The electronics are inside a foam block which is compressed inside a solid milled temperature-controlled outer box which itself is enclosed in foam, and then glued into a sturdy rack case.  I haven't gone all time-nutty and encased it in a buried concrete block (yet).

I used a tantalum to start with, but it seemed a bit unstable, hence the swapout for a ceramic.  The ones I am using were TDK, nearly four quid each when I bought them, and they are in 1812 packages.  Their V/C slope performance is reasonable, but the main reason I chose them was that the dielectric absorption effects are reasonably low at the 2-3V level, despite all that Barium titanate.  I am guessing that the V/C slope and dielectric absorption would only affect the speed and stability of the loop as it locked-in, and the OCXO needs 15 minutes to stabilise anyway.  Once it is locked and everything has settled down, the V/C and polarisation effects shouldn't really matter, should they?  I should probably have stuck with the tantalums and let it settle down for a week, but I was impatient and (as usual) had no idea what I was doing.

Anyway, it seems to behave impeccably in this application, given the mechanical and thermal isolation.  When I am /P, I just take the rack case out of the radio room rack and put in into the motorhome rack.  Everyone *does* have a 19 inch rack in their motorhome for radio kit, right?

Back on topic, I'll report on what improvement I see in the 5355s with Brian's mods (and if I can fit some 0402 bypass caps, whether that helps at all)

Neil G4DBN


On 22/12/2017 17:55, Christopher Bartram cbartram@... [ukmicrowaves] wrote:
 

Andy, Neil,

< Be sure your 47uF ceramic caps are not microphonic or exhibit
non-linear V/C characteristics

I'd be reasonably relaxed about the C - V characteristics of ceramic
capacitors used for decoupling, and have used them extensively, choosing
the suitable material mixes for different applications. All ceramic
capacitors are not created equal! BUT, I'd be very cautious about using
many ceramic caps in PLL filters. It really can be a great way of making
a radio microphone!

There is one exception: NPO/COG materials are pretty immune to
microphony. All others are are, to some extent, not! Surface mount NPO
capacitors of >10nF and reasonable size start to become unobtanium. Good
practice is to use film dielectric parts, such as the Panasonic ECHU
series, but even they are not entirely trouble-free. Many plastic
materials - pfte is an exception - suffer from an effect called
dielectric absorption, which is a a memory effect where charge is stored
in the dielectric material. That can wreak havoc with the performance of
loop filters.

73

Chris

GW4DGU