Re: [time-nuts] Modern signal generators

[David Van Horn]

> Coax is always a challenge because the shields leak.

FSJ1-50 works for me.   Maintaining ham VHF repeaters where I'm putting 100W up 
the pipe and looking for -114dBm at the receiver, I have had big improvements 
replacing even good coax with heliax and real silver/Teflon connectors.

Of course if you need Radiax, Tandy RG-58 was a good inexpensive substitute.


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Re: [time-nuts] Modern signal generators

[Wes]

I am reminded of the time before retirement that I put together an RF lab at 
Hughes Missile Systems.  All of the equipment was housed in a shielded room, 
since in addition to all of the garbage generated in our own factory we were 
located at Tucson International Airport with all of their comm and radar stuff 
operating.  I specified the room to have 120 dB isolation from a few kHz to 10 
GHz.  It was modular panels 2 inches thick with galvanized steel shielding on 
both sides.  The door was massive with a brass jam and a knife edge that was 
driven into double finger stock backed up by conductive foam.


The vendor performed proof-of-performance by putting a spectrum analyzer fed 
with a standard gain X-band horn inside and a TWT amplifier on the outside also 
feeding a horn aimed at the one inside.  The system was normalized with the door 
open and then tested with the door closed.  It met the requirement, but with 
little margin.


I was given instructions on how to maintain the room, with emphasis on cleaning 
the door edge and finger stock.  To drive home the importance, the guy took a 
dollar bill out of his wallet and placed it across the finger stock channel and 
then closed the door.  The isolation dropped over 20 dB.


Wes  N7WS

On 12/12/2018 10:56 AM, jimlux wrote:


At JPL we regularly do measurements of signals at <-150 dBm into sensitive 
deep space receivers, and we're obsessive about phase (since that's how we 
measure the distance to spacecraft to a gnat's eyelash). Historically, we 
found, for instance that most signal generators leak more through the chassis 
than come out the output jack at minimum level.   We test the receivers in a 
screen room, with the generators outside, so you get about 100dB from the 
screen room to help. Waveguide helps too (WG below cutoff is a very effective 
filter) and it's not too tough to make waveguide joints that have better than 
150dB isolation to the outside (lap them smooth, use pins, wrap in foil tape)


Coax is always a challenge because the shields leak.



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Re: [time-nuts] Modern signal generators

[Ulrich Rohde via time-nuts]

YES 7851 I hope 
 
In a message dated 12/12/2018 3:43:23 PM Eastern Standard Time, 
rich...@karlquist.com writes:

 
 FWIW, the HMC832 has FOM of -226. The best synth on a chip
now available AFAIK has FOM of -236. That's 10 dB better.

Rick N6RK

On 12/12/2018 10:46 AM, Dr. Ulrich L. Rohde via time-nuts wrote:
> I did some phase noise measurement and the 8751 is much better then the rest 
> on the market
> 
> Sent from my iPhone
> 
>> On Dec 12, 2018, at 1:20 PM, Bob kb8tq  wrote:
>>
>> Hi
>>
>> Just to save others the time digging, the 7851 uses a HMC832 VCO + 
>> fractional N PLL on a chip as
>> the heart of its synthesizer. Yet another “way to go” if building a quick 
>> and simple signal source.
>>
>> ===
>>
>> No argument at all about other parts of the radio having their limits. PA 
>> performance certainly is one
>> of those areas.
>>
>> Bob
>>
>>> On Dec 12, 2018, at 12:42 PM, Dr. Ulrich L. Rohde via time-nuts 
>>>  wrote:
>>>
>>> My feeling is
>>> A Because of the low sunspot cycle the large signal performance of the RX 
>>> is less a topic, the ICOM 7851 dynamic range, synthesizer and frequency 
>>> concept is winning but expensive
>>> B The power amplifier from 100 W to 1500 Watt need to be catching up to the 
>>> old Collins tube Amps with negative feedback, producing - 45 dB or better 
>>> IMD products.
>>>
>>> The military amplifier are fast on , reliable , durable and expensive... 
>>> initially.
>>>
>>> The noisy blower may be a bad thing.
>>>
>>> I “only “ run 1 KW, and I am happy with it
>>>
>>> 73 de N1UL
>>>
>>> Sent from my iPhone
>>>
 On Dec 12, 2018, at 10:47 AM, Bob kb8tq  wrote:

 Hi

 Usually on HF, the issue is large signal rejection. Phase noise very 
 definitely
 gets into that part of things. Other components in the signal chain do as 
 well.
 Once the synthesizer is no longer the weak link in the chain, spending more
 to improve it (vs spending on the other components) probably does not make
 a lot of sense. Since the synthesizer is *far* from ideal, that sort of 
 begs the
 question of just how troublesome the other parts are and how much better a
 device *could* be built.

 This does seem to be wandering a bit from a Time related topic …..

 It does illustrate the point that “good enough” may be way far away from
 “pretty good” and yet even more distant from “as good as it gets”. The
 question on any system is always “how good do you need / what are you
 doing?” ….

 Bob

> On Dec 12, 2018, at 8:49 AM, jimlux  wrote:
>
> On 12/11/18 3:26 PM, Bob kb8tq wrote:
>> Hi
>> As I said, just how rational using these parts in a radio …. not at all 
>> clear to me.
>> Back when I went to school, stuff that was this noisy was not in the 
>> “greatest” category.
>> That was a *very* long time ago.
>> Oddly enough best performance synthesizers have gotten better. (as the 
>> posted
>> presentations very clearly show). Just why a “high end” radio uses a 
>> less than
>> ideal synthesizer likely relates more to cost (even at a price of 
>> thousands of dollars)
>> than to anything else.
>
> Or "good enough" performance - driving to a 3 dB NF for a HF receiver 
> while maintaining good strong signal performance is probably not worth it
>
>
>> Indeed cost also drives things like GPSDO’s and GPS modules. We often 
>> are not
>> very eager to acknowledge that fact.
>> Bob
>
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> time-nuts mailing list -- time-nuts@lists.febo.com
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Re: [time-nuts] Modern signal generators

[Ulrich Rohde via time-nuts]

That is almost true, depending on the PhFreq. discriminator 
 
In a message dated 12/12/2018 3:56:49 PM Eastern Standard Time, 
rich...@karlquist.com writes:

 
 The TI/NationalSemiconductor LMX2594 and LMX2595 have the best
phase noise floor FOM at -236.

The AnalogDevices/LinearTechnology LTC6952 has the best flicker at -281.
It requires an external VCO. The LTC6951 with an on board VCO is
almost as good.

Although these are state of the air for a synthesizer-on-a-chip,
it is easy to beat them if you roll your own with a mixer as
a phase detector.

Rick N6RK

On 12/12/2018 12:44 PM, Ulrich Rohde wrote:
> Who makes it ?
> 
> In a message dated 12/12/2018 3:43:23 PM Eastern Standard Time, 
> rich...@karlquist.com writes:
> 
> FWIW, the HMC832 has FOM of -226. The best synth on a chip
> now available AFAIK has FOM of -236. That's 10 dB better.
> 
> Rick N6RK
> 
> On 12/12/2018 10:46 AM, Dr. Ulrich L. Rohde via time-nuts wrote:
> > I did some phase noise measurement and the 8751 is much better then the 
> > rest on the market
> > 
> > Sent from my iPhone
> > 
> >> On Dec 12, 2018, at 1:20 PM, Bob kb8tq  >> > wrote:
> >>
> >> Hi
> >>
> >> Just to save others the time digging, the 7851 uses a HMC832 VCO + 
> >> fractional N PLL on a chip as
> >> the heart of its synthesizer. Yet another “way to go” if building a quick 
> >> and simple signal source.
> >>
> >> ===
> >>
> >> No argument at all about other parts of the radio having their limits. PA 
> >> performance certainly is one
> >> of those areas.
> >>
> >> Bob
> >>
> >>> On Dec 12, 2018, at 12:42 PM, Dr. Ulrich L. Rohde via time-nuts 
> >>> mailto:n...@lists.febo.com>> wrote:
> >>>
> >>> My feeling is
> >>> A Because of the low sunspot cycle the large signal performance of the RX 
> >>> is less a topic, the ICOM 7851 dynamic range, synthesizer and frequency 
> >>> concept is winning but expensive
> >>> B The power amplifier from 100 W to 1500 Watt need to be catching up to 
> >>> the old Collins tube Amps with negative feedback, producing - 45 dB or 
> >>> better IMD products.
> >>>
> >>> The military amplifier are fast on , reliable , durable and expensive... 
> >>> initially.
> >>>
> >>> The noisy blower may be a bad thing.
> >>>
> >>> I “only “ run 1 KW, and I am happy with it
> >>>
> >>> 73 de N1UL
> >>>
> >>> Sent from my iPhone
> >>>
>  On Dec 12, 2018, at 10:47 AM, Bob kb8tq   > wrote:
> 
>  Hi
> 
>  Usually on HF, the issue is large signal rejection. Phase noise very 
>  definitely
>  gets into that part of things. Other components in the signal chain do 
>  as well.
>  Once the synthesizer is no longer the weak link in the chain, spending 
>  more
>  to improve it (vs spending on the other components) probably does not 
>  make
>  a lot of sense. Since the synthesizer is *far* from ideal, that sort of 
>  begs the
>  question of just how troublesome the other parts are and how much better 
>  a
>  device *could* be built.
> 
>  This does seem to be wandering a bit from a Time related topic …..
> 
>  It does illustrate the point that “good enough” may be way far away from
>  “pretty good” and yet even more distant from “as good as it gets”. The
>  question on any system is always “how good do you need / what are you
>  doing?” ….
> 
>  Bob
> 
> > On Dec 12, 2018, at 8:49 AM, jimlux  > > wrote:
> >
> > On 12/11/18 3:26 PM, Bob kb8tq wrote:
> >> Hi
> >> As I said, just how rational using these parts in a radio …. not at 
> >> all clear to me.
> >> Back when I went to school, stuff that was this noisy was not in the 
> >> “greatest” category.
> >> That was a *very* long time ago.
> >> Oddly enough best performance synthesizers have gotten better. (as the 
> >> posted
> >> presentations very clearly show). Just why a “high end” radio uses a 
> >> less than
> >> ideal synthesizer likely relates more to cost (even at a price of 
> >> thousands of dollars)
> >> than to anything else.
> >
> > Or "good enough" performance - driving to a 3 dB NF for a HF receiver 
> > while maintaining good strong signal performance is probably not worth 
> > it
> >
> >
> >> Indeed cost also drives things like GPSDO’s and GPS modules. We often 
> >> are not
> >> very eager to acknowledge that fact.
> >> Bob
> >
> > ___
> > time-nuts mailing list -- time-nuts@lists.febo.com 
> > 
> > To unsubscribe, go to 
> > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> > and follow the instructions there.
> 
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Re: [time-nuts] Modern signal generators

[Gerhard Hoffmann]

Am 12.12.18 um 21:56 schrieb Richard (Rick) Karlquist:

The TI/NationalSemiconductor LMX2594 and LMX2595 have the best
phase noise floor FOM at -236.

The AnalogDevices/LinearTechnology LTC6952 has the best flicker at -281.
It requires an external VCO.  The LTC6951 with an on board VCO is
almost as good.

Although these are state of the air for a synthesizer-on-a-chip,
it is easy to beat them if you roll your own with a mixer as
a phase detector.



And the ADF4371 at -234

62.5 MHz to 32,000 MHz. Speedy. SMA is no longer good enough.

\Gerhard


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Re: [time-nuts] Modern signal generators

[Richard (Rick) Karlquist]

The TI/NationalSemiconductor LMX2594 and LMX2595 have the best
phase noise floor FOM at -236.

The AnalogDevices/LinearTechnology LTC6952 has the best flicker at -281.
It requires an external VCO.  The LTC6951 with an on board VCO is
almost as good.

Although these are state of the air for a synthesizer-on-a-chip,
it is easy to beat them if you roll your own with a mixer as
a phase detector.

Rick N6RK

On 12/12/2018 12:44 PM, Ulrich Rohde wrote:

Who makes it ?

In a message dated 12/12/2018 3:43:23 PM Eastern Standard Time, 
rich...@karlquist.com writes:


FWIW, the HMC832 has FOM of -226. The best synth on a chip
now available AFAIK has FOM of -236. That's 10 dB better.

Rick N6RK

On 12/12/2018 10:46 AM, Dr. Ulrich L. Rohde via time-nuts wrote:
> I did some phase noise measurement and the 8751 is much better then the 
rest on the market
> 
> Sent from my iPhone
> 
>> On Dec 12, 2018, at 1:20 PM, Bob kb8tq mailto:kb...@n1k.org>> wrote:

>>
>> Hi
>>
>> Just to save others the time digging, the 7851 uses a HMC832 VCO + 
fractional N PLL on a chip as
>> the heart of its synthesizer. Yet another “way to go” if building a 
quick and simple signal source.
>>
>> ===
>>
>> No argument at all about other parts of the radio having their limits. 
PA performance certainly is one
>> of those areas.
>>
>> Bob
>>
>>> On Dec 12, 2018, at 12:42 PM, Dr. Ulrich L. Rohde via time-nuts 
mailto:n...@lists.febo.com>> wrote:
>>>
>>> My feeling is
>>> A Because of the low sunspot cycle the large signal performance of the 
RX is less a topic, the ICOM 7851 dynamic range, synthesizer and frequency concept is 
winning but expensive
>>> B The power amplifier from 100 W to 1500 Watt need to be catching up to 
the old Collins tube Amps with negative feedback, producing - 45 dB or better IMD 
products.
>>>
>>> The military amplifier are fast on , reliable , durable and 
expensive... initially.
>>>
>>> The noisy blower may be a bad thing.
>>>
>>> I “only “ run 1 KW, and I am happy with it
>>>
>>> 73 de N1UL
>>>
>>> Sent from my iPhone
>>>
 On Dec 12, 2018, at 10:47 AM, Bob kb8tq mailto:kb...@n1k.org>> wrote:

 Hi

 Usually on HF, the issue is large signal rejection. Phase noise very 
definitely
 gets into that part of things. Other components in the signal chain do 
as well.
 Once the synthesizer is no longer the weak link in the chain, spending 
more
 to improve it (vs spending on the other components) probably does not 
make
 a lot of sense. Since the synthesizer is *far* from ideal, that sort 
of begs the
 question of just how troublesome the other parts are and how much 
better a
 device *could* be built.

 This does seem to be wandering a bit from a Time related topic …..

 It does illustrate the point that “good enough” may be way far away 
from
 “pretty good” and yet even more distant from “as good as it gets”. The
 question on any system is always “how good do you need / what are you
 doing?” ….

 Bob

> On Dec 12, 2018, at 8:49 AM, jimlux mailto:jim...@earthlink.net>> wrote:
>
> On 12/11/18 3:26 PM, Bob kb8tq wrote:
>> Hi
>> As I said, just how rational using these parts in a radio …. not at 
all clear to me.
>> Back when I went to school, stuff that was this noisy was not in the 
“greatest” category.
>> That was a *very* long time ago.
>> Oddly enough best performance synthesizers have gotten better. (as 
the posted
>> presentations very clearly show). Just why a “high end” radio uses a 
less than
>> ideal synthesizer likely relates more to cost (even at a price of 
thousands of dollars)
>> than to anything else.
>
> Or "good enough" performance - driving to a 3 dB NF for a HF receiver 
while maintaining good strong signal performance is probably not worth it
>
>
>> Indeed cost also drives things like GPSDO’s and GPS modules. We 
often are not
>> very eager to acknowledge that fact.
>> Bob
>
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com 

> To unsubscribe, go to 
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Re: [time-nuts] Modern signal generators

[Magnus Danielson]

Hi Ulrich,

Analog/Hitite
https://eu.mouser.com/new/hittite-microwave/hittite-hmc832-pll/

Cheers,
Magnus


On 12/12/18 9:44 PM, Ulrich Rohde via time-nuts wrote:
> Who makes it ?
>  
> In a message dated 12/12/2018 3:43:23 PM Eastern Standard Time, 
> rich...@karlquist.com writes:
> 
>  
>  FWIW, the HMC832 has FOM of -226. The best synth on a chip
> now available AFAIK has FOM of -236. That's 10 dB better.
> 
> Rick N6RK
> 
> On 12/12/2018 10:46 AM, Dr. Ulrich L. Rohde via time-nuts wrote:
>> I did some phase noise measurement and the 8751 is much better then the rest 
>> on the market
>>
>> Sent from my iPhone
>>
>>> On Dec 12, 2018, at 1:20 PM, Bob kb8tq  wrote:
>>>
>>> Hi
>>>
>>> Just to save others the time digging, the 7851 uses a HMC832 VCO + 
>>> fractional N PLL on a chip as
>>> the heart of its synthesizer. Yet another “way to go” if building a quick 
>>> and simple signal source.
>>>
>>> ===
>>>
>>> No argument at all about other parts of the radio having their limits. PA 
>>> performance certainly is one
>>> of those areas.
>>>
>>> Bob
>>>
 On Dec 12, 2018, at 12:42 PM, Dr. Ulrich L. Rohde via time-nuts 
  wrote:

 My feeling is
 A Because of the low sunspot cycle the large signal performance of the RX 
 is less a topic, the ICOM 7851 dynamic range, synthesizer and frequency 
 concept is winning but expensive
 B The power amplifier from 100 W to 1500 Watt need to be catching up to 
 the old Collins tube Amps with negative feedback, producing - 45 dB or 
 better IMD products.

 The military amplifier are fast on , reliable , durable and expensive... 
 initially.

 The noisy blower may be a bad thing.

 I “only “ run 1 KW, and I am happy with it

 73 de N1UL

 Sent from my iPhone

> On Dec 12, 2018, at 10:47 AM, Bob kb8tq  wrote:
>
> Hi
>
> Usually on HF, the issue is large signal rejection. Phase noise very 
> definitely
> gets into that part of things. Other components in the signal chain do as 
> well.
> Once the synthesizer is no longer the weak link in the chain, spending 
> more
> to improve it (vs spending on the other components) probably does not make
> a lot of sense. Since the synthesizer is *far* from ideal, that sort of 
> begs the
> question of just how troublesome the other parts are and how much better a
> device *could* be built.
>
> This does seem to be wandering a bit from a Time related topic …..
>
> It does illustrate the point that “good enough” may be way far away from
> “pretty good” and yet even more distant from “as good as it gets”. The
> question on any system is always “how good do you need / what are you
> doing?” ….
>
> Bob
>
>> On Dec 12, 2018, at 8:49 AM, jimlux  wrote:
>>
>> On 12/11/18 3:26 PM, Bob kb8tq wrote:
>>> Hi
>>> As I said, just how rational using these parts in a radio …. not at all 
>>> clear to me.
>>> Back when I went to school, stuff that was this noisy was not in the 
>>> “greatest” category.
>>> That was a *very* long time ago.
>>> Oddly enough best performance synthesizers have gotten better. (as the 
>>> posted
>>> presentations very clearly show). Just why a “high end” radio uses a 
>>> less than
>>> ideal synthesizer likely relates more to cost (even at a price of 
>>> thousands of dollars)
>>> than to anything else.
>>
>> Or "good enough" performance - driving to a 3 dB NF for a HF receiver 
>> while maintaining good strong signal performance is probably not worth it
>>
>>
>>> Indeed cost also drives things like GPSDO’s and GPS modules. We often 
>>> are not
>>> very eager to acknowledge that fact.
>>> Bob
>>
>> ___
>> time-nuts mailing list -- time-nuts@lists.febo.com
>> To unsubscribe, go to 
>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
>> and follow the instructions there.
>
>
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>>>
>>>
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Re: [time-nuts] Modern signal generators

[Gregory Maxwell]

Googling -236 figure of merit synthesizer yields:

http://www.ti.com/product/LMX2594
On Wed, Dec 12, 2018 at 8:46 PM Ulrich Rohde via time-nuts
 wrote:
>
> Who makes it ?
>
> In a message dated 12/12/2018 3:43:23 PM Eastern Standard Time, 
> rich...@karlquist.com writes:
>
>
>  FWIW, the HMC832 has FOM of -226. The best synth on a chip
> now available AFAIK has FOM of -236. That's 10 dB better.
>
> Rick N6RK
>
> On 12/12/2018 10:46 AM, Dr. Ulrich L. Rohde via time-nuts wrote:
> > I did some phase noise measurement and the 8751 is much better then the 
> > rest on the market
> >
> > Sent from my iPhone
> >
> >> On Dec 12, 2018, at 1:20 PM, Bob kb8tq  wrote:
> >>
> >> Hi
> >>
> >> Just to save others the time digging, the 7851 uses a HMC832 VCO + 
> >> fractional N PLL on a chip as
> >> the heart of its synthesizer. Yet another “way to go” if building a quick 
> >> and simple signal source.
> >>
> >> ===
> >>
> >> No argument at all about other parts of the radio having their limits. PA 
> >> performance certainly is one
> >> of those areas.
> >>
> >> Bob
> >>
> >>> On Dec 12, 2018, at 12:42 PM, Dr. Ulrich L. Rohde via time-nuts 
> >>>  wrote:
> >>>
> >>> My feeling is
> >>> A Because of the low sunspot cycle the large signal performance of the RX 
> >>> is less a topic, the ICOM 7851 dynamic range, synthesizer and frequency 
> >>> concept is winning but expensive
> >>> B The power amplifier from 100 W to 1500 Watt need to be catching up to 
> >>> the old Collins tube Amps with negative feedback, producing - 45 dB or 
> >>> better IMD products.
> >>>
> >>> The military amplifier are fast on , reliable , durable and expensive... 
> >>> initially.
> >>>
> >>> The noisy blower may be a bad thing.
> >>>
> >>> I “only “ run 1 KW, and I am happy with it
> >>>
> >>> 73 de N1UL
> >>>
> >>> Sent from my iPhone
> >>>
>  On Dec 12, 2018, at 10:47 AM, Bob kb8tq  wrote:
> 
>  Hi
> 
>  Usually on HF, the issue is large signal rejection. Phase noise very 
>  definitely
>  gets into that part of things. Other components in the signal chain do 
>  as well.
>  Once the synthesizer is no longer the weak link in the chain, spending 
>  more
>  to improve it (vs spending on the other components) probably does not 
>  make
>  a lot of sense. Since the synthesizer is *far* from ideal, that sort of 
>  begs the
>  question of just how troublesome the other parts are and how much better 
>  a
>  device *could* be built.
> 
>  This does seem to be wandering a bit from a Time related topic …..
> 
>  It does illustrate the point that “good enough” may be way far away from
>  “pretty good” and yet even more distant from “as good as it gets”. The
>  question on any system is always “how good do you need / what are you
>  doing?” ….
> 
>  Bob
> 
> > On Dec 12, 2018, at 8:49 AM, jimlux  wrote:
> >
> > On 12/11/18 3:26 PM, Bob kb8tq wrote:
> >> Hi
> >> As I said, just how rational using these parts in a radio …. not at 
> >> all clear to me.
> >> Back when I went to school, stuff that was this noisy was not in the 
> >> “greatest” category.
> >> That was a *very* long time ago.
> >> Oddly enough best performance synthesizers have gotten better. (as the 
> >> posted
> >> presentations very clearly show). Just why a “high end” radio uses a 
> >> less than
> >> ideal synthesizer likely relates more to cost (even at a price of 
> >> thousands of dollars)
> >> than to anything else.
> >
> > Or "good enough" performance - driving to a 3 dB NF for a HF receiver 
> > while maintaining good strong signal performance is probably not worth 
> > it
> >
> >
> >> Indeed cost also drives things like GPSDO’s and GPS modules. We often 
> >> are not
> >> very eager to acknowledge that fact.
> >> Bob
> >
> > ___
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> > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
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> >>>
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Re: [time-nuts] Modern signal generators

[Ulrich Rohde via time-nuts]

Who makes it ?
 
In a message dated 12/12/2018 3:43:23 PM Eastern Standard Time, 
rich...@karlquist.com writes:

 
 FWIW, the HMC832 has FOM of -226. The best synth on a chip
now available AFAIK has FOM of -236. That's 10 dB better.

Rick N6RK

On 12/12/2018 10:46 AM, Dr. Ulrich L. Rohde via time-nuts wrote:
> I did some phase noise measurement and the 8751 is much better then the rest 
> on the market
> 
> Sent from my iPhone
> 
>> On Dec 12, 2018, at 1:20 PM, Bob kb8tq  wrote:
>>
>> Hi
>>
>> Just to save others the time digging, the 7851 uses a HMC832 VCO + 
>> fractional N PLL on a chip as
>> the heart of its synthesizer. Yet another “way to go” if building a quick 
>> and simple signal source.
>>
>> ===
>>
>> No argument at all about other parts of the radio having their limits. PA 
>> performance certainly is one
>> of those areas.
>>
>> Bob
>>
>>> On Dec 12, 2018, at 12:42 PM, Dr. Ulrich L. Rohde via time-nuts 
>>>  wrote:
>>>
>>> My feeling is
>>> A Because of the low sunspot cycle the large signal performance of the RX 
>>> is less a topic, the ICOM 7851 dynamic range, synthesizer and frequency 
>>> concept is winning but expensive
>>> B The power amplifier from 100 W to 1500 Watt need to be catching up to the 
>>> old Collins tube Amps with negative feedback, producing - 45 dB or better 
>>> IMD products.
>>>
>>> The military amplifier are fast on , reliable , durable and expensive... 
>>> initially.
>>>
>>> The noisy blower may be a bad thing.
>>>
>>> I “only “ run 1 KW, and I am happy with it
>>>
>>> 73 de N1UL
>>>
>>> Sent from my iPhone
>>>
 On Dec 12, 2018, at 10:47 AM, Bob kb8tq  wrote:

 Hi

 Usually on HF, the issue is large signal rejection. Phase noise very 
 definitely
 gets into that part of things. Other components in the signal chain do as 
 well.
 Once the synthesizer is no longer the weak link in the chain, spending more
 to improve it (vs spending on the other components) probably does not make
 a lot of sense. Since the synthesizer is *far* from ideal, that sort of 
 begs the
 question of just how troublesome the other parts are and how much better a
 device *could* be built.

 This does seem to be wandering a bit from a Time related topic …..

 It does illustrate the point that “good enough” may be way far away from
 “pretty good” and yet even more distant from “as good as it gets”. The
 question on any system is always “how good do you need / what are you
 doing?” ….

 Bob

> On Dec 12, 2018, at 8:49 AM, jimlux  wrote:
>
> On 12/11/18 3:26 PM, Bob kb8tq wrote:
>> Hi
>> As I said, just how rational using these parts in a radio …. not at all 
>> clear to me.
>> Back when I went to school, stuff that was this noisy was not in the 
>> “greatest” category.
>> That was a *very* long time ago.
>> Oddly enough best performance synthesizers have gotten better. (as the 
>> posted
>> presentations very clearly show). Just why a “high end” radio uses a 
>> less than
>> ideal synthesizer likely relates more to cost (even at a price of 
>> thousands of dollars)
>> than to anything else.
>
> Or "good enough" performance - driving to a 3 dB NF for a HF receiver 
> while maintaining good strong signal performance is probably not worth it
>
>
>> Indeed cost also drives things like GPSDO’s and GPS modules. We often 
>> are not
>> very eager to acknowledge that fact.
>> Bob
>
> ___
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>>>
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Re: [time-nuts] Modern signal generators

[Richard (Rick) Karlquist]

FWIW, the HMC832 has FOM of -226.  The best synth on a chip
now available AFAIK has FOM of -236. That's 10 dB better.

Rick N6RK

On 12/12/2018 10:46 AM, Dr. Ulrich L. Rohde via time-nuts wrote:

I did some phase noise measurement and the 8751 is much better then the rest on 
the market

Sent from my iPhone


On Dec 12, 2018, at 1:20 PM, Bob kb8tq  wrote:

Hi

Just to save others the time digging, the 7851 uses a HMC832 VCO + fractional N 
PLL on a chip as
the heart of its synthesizer. Yet another “way to go” if building a quick and 
simple signal source.

===

No argument at all about other parts of the radio having their limits. PA 
performance certainly is one
of those areas.

Bob


On Dec 12, 2018, at 12:42 PM, Dr. Ulrich L. Rohde via time-nuts 
 wrote:

My feeling is
A Because of the low sunspot cycle the large signal performance of the RX is 
less a topic, the ICOM 7851 dynamic range, synthesizer and frequency concept is 
winning but expensive
B The power amplifier from 100 W to 1500 Watt need to be catching up to the old 
Collins tube Amps with negative feedback, producing - 45 dB or better IMD 
products.

The military amplifier are fast on , reliable , durable and expensive... 
initially.

The noisy blower may be a bad thing.

I “only “ run 1 KW, and I am happy with it

73 de N1UL

Sent from my iPhone


On Dec 12, 2018, at 10:47 AM, Bob kb8tq  wrote:

Hi

Usually on HF, the issue is large signal rejection. Phase noise very definitely
gets into that part of things. Other components in the signal chain do as well.
Once the synthesizer is no longer the weak link in the chain, spending more
to improve it (vs spending on the other components) probably does not make
a lot of sense. Since the synthesizer is *far* from ideal, that sort of begs the
question of just how troublesome the other parts are and how much better a
device *could* be built.

This does seem to be wandering a bit from a Time related topic …..

It does illustrate the point that “good enough” may be way far  away from
“pretty good” and yet even more distant from “as good as it gets”.  The
question on any system is always “how good do you need / what are you
doing?” ….

Bob


On Dec 12, 2018, at 8:49 AM, jimlux  wrote:

On 12/11/18 3:26 PM, Bob kb8tq wrote:

Hi
As I said, just how rational using these parts in a radio …. not at all clear 
to me.
Back when I went to school, stuff that was this noisy was not in the “greatest” 
category.
That was a *very* long time ago.
Oddly enough best performance synthesizers have gotten better. (as the posted
presentations very clearly show). Just why a “high end” radio uses a less than
ideal synthesizer likely relates more to cost (even at a price of thousands of 
dollars)
than to anything else.


Or "good enough" performance - driving to a 3 dB NF for a HF receiver while 
maintaining good strong signal performance is probably not worth it



Indeed cost also drives things like GPSDO’s and GPS modules. We often are not
very eager to acknowledge that fact.
Bob


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Re: [time-nuts] Modern signal generators

[Bob kb8tq]

Hi

I assume 8751 = 7851 (says Bob who makes typo’s in about every second sentence 
:) ).

I’m not at all surprised it’s doing better than the radios with SiLabs parts. 
They dominate 
the market once you get to the “rest of the pack”. Of course those radios are 
half the price 
(or less) than the 7851.

Bob

> On Dec 12, 2018, at 1:46 PM, Dr. Ulrich L. Rohde via time-nuts 
>  wrote:
> 
> I did some phase noise measurement and the 8751 is much better then the rest 
> on the market 
> 
> Sent from my iPhone
> 
>> On Dec 12, 2018, at 1:20 PM, Bob kb8tq  wrote:
>> 
>> Hi
>> 
>> Just to save others the time digging, the 7851 uses a HMC832 VCO + 
>> fractional N PLL on a chip as
>> the heart of its synthesizer. Yet another “way to go” if building a quick 
>> and simple signal source. 
>> 
>> ===
>> 
>> No argument at all about other parts of the radio having their limits. PA 
>> performance certainly is one
>> of those areas. 
>> 
>> Bob
>> 
>>> On Dec 12, 2018, at 12:42 PM, Dr. Ulrich L. Rohde via time-nuts 
>>>  wrote:
>>> 
>>> My feeling is
>>> A Because of the low sunspot cycle the large signal performance of the RX 
>>> is less a topic, the ICOM 7851 dynamic range, synthesizer and frequency 
>>> concept is winning but expensive 
>>> B The power amplifier from 100 W to 1500 Watt need to be catching up to the 
>>> old Collins tube Amps with negative feedback, producing - 45 dB or better 
>>> IMD products.
>>> 
>>> The military amplifier are fast on , reliable , durable and expensive... 
>>> initially.
>>> 
>>> The noisy blower may be a bad thing.
>>> 
>>> I “only “ run 1 KW, and I am happy with it
>>> 
>>> 73 de N1UL 
>>> 
>>> Sent from my iPhone
>>> 
 On Dec 12, 2018, at 10:47 AM, Bob kb8tq  wrote:
 
 Hi
 
 Usually on HF, the issue is large signal rejection. Phase noise very 
 definitely 
 gets into that part of things. Other components in the signal chain do as 
 well.
 Once the synthesizer is no longer the weak link in the chain, spending more
 to improve it (vs spending on the other components) probably does not make 
 a lot of sense. Since the synthesizer is *far* from ideal, that sort of 
 begs the
 question of just how troublesome the other parts are and how much better a 
 device *could* be built.
 
 This does seem to be wandering a bit from a Time related topic …..
 
 It does illustrate the point that “good enough” may be way far  away from 
 “pretty good” and yet even more distant from “as good as it gets”.  The 
 question on any system is always “how good do you need / what are you 
 doing?” …. 
 
 Bob
 
> On Dec 12, 2018, at 8:49 AM, jimlux  wrote:
> 
> On 12/11/18 3:26 PM, Bob kb8tq wrote:
>> Hi
>> As I said, just how rational using these parts in a radio …. not at all 
>> clear to me.
>> Back when I went to school, stuff that was this noisy was not in the 
>> “greatest” category.
>> That was a *very* long time ago.
>> Oddly enough best performance synthesizers have gotten better. (as the 
>> posted
>> presentations very clearly show). Just why a “high end” radio uses a 
>> less than
>> ideal synthesizer likely relates more to cost (even at a price of 
>> thousands of dollars)
>> than to anything else.
> 
> Or "good enough" performance - driving to a 3 dB NF for a HF receiver 
> while maintaining good strong signal performance is probably not worth it
> 
> 
>> Indeed cost also drives things like GPSDO’s and GPS modules. We often 
>> are not
>> very eager to acknowledge that fact.
>> Bob
> 
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to 
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
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>>> 
>>> 
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Re: [time-nuts] Modern signal generators

[Dr. Ulrich L. Rohde via time-nuts]

I did some phase noise measurement and the 8751 is much better then the rest on 
the market 

Sent from my iPhone

> On Dec 12, 2018, at 1:20 PM, Bob kb8tq  wrote:
> 
> Hi
> 
> Just to save others the time digging, the 7851 uses a HMC832 VCO + fractional 
> N PLL on a chip as
> the heart of its synthesizer. Yet another “way to go” if building a quick and 
> simple signal source. 
> 
> ===
> 
> No argument at all about other parts of the radio having their limits. PA 
> performance certainly is one
> of those areas. 
> 
> Bob
> 
>> On Dec 12, 2018, at 12:42 PM, Dr. Ulrich L. Rohde via time-nuts 
>>  wrote:
>> 
>> My feeling is
>> A Because of the low sunspot cycle the large signal performance of the RX is 
>> less a topic, the ICOM 7851 dynamic range, synthesizer and frequency concept 
>> is winning but expensive 
>> B The power amplifier from 100 W to 1500 Watt need to be catching up to the 
>> old Collins tube Amps with negative feedback, producing - 45 dB or better 
>> IMD products.
>> 
>> The military amplifier are fast on , reliable , durable and expensive... 
>> initially.
>> 
>> The noisy blower may be a bad thing.
>> 
>> I “only “ run 1 KW, and I am happy with it
>> 
>> 73 de N1UL 
>> 
>> Sent from my iPhone
>> 
>>> On Dec 12, 2018, at 10:47 AM, Bob kb8tq  wrote:
>>> 
>>> Hi
>>> 
>>> Usually on HF, the issue is large signal rejection. Phase noise very 
>>> definitely 
>>> gets into that part of things. Other components in the signal chain do as 
>>> well.
>>> Once the synthesizer is no longer the weak link in the chain, spending more
>>> to improve it (vs spending on the other components) probably does not make 
>>> a lot of sense. Since the synthesizer is *far* from ideal, that sort of 
>>> begs the
>>> question of just how troublesome the other parts are and how much better a 
>>> device *could* be built.
>>> 
>>> This does seem to be wandering a bit from a Time related topic …..
>>> 
>>> It does illustrate the point that “good enough” may be way far  away from 
>>> “pretty good” and yet even more distant from “as good as it gets”.  The 
>>> question on any system is always “how good do you need / what are you 
>>> doing?” …. 
>>> 
>>> Bob
>>> 
 On Dec 12, 2018, at 8:49 AM, jimlux  wrote:
 
 On 12/11/18 3:26 PM, Bob kb8tq wrote:
> Hi
> As I said, just how rational using these parts in a radio …. not at all 
> clear to me.
> Back when I went to school, stuff that was this noisy was not in the 
> “greatest” category.
> That was a *very* long time ago.
> Oddly enough best performance synthesizers have gotten better. (as the 
> posted
> presentations very clearly show). Just why a “high end” radio uses a less 
> than
> ideal synthesizer likely relates more to cost (even at a price of 
> thousands of dollars)
> than to anything else.
 
 Or "good enough" performance - driving to a 3 dB NF for a HF receiver 
 while maintaining good strong signal performance is probably not worth it
 
 
> Indeed cost also drives things like GPSDO’s and GPS modules. We often are 
> not
> very eager to acknowledge that fact.
> Bob
 
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>>> 
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Re: [time-nuts] Modern signal generators

[Bob kb8tq]

Hi

Just to save others the time digging, the 7851 uses a HMC832 VCO + fractional N 
PLL on a chip as
the heart of its synthesizer. Yet another “way to go” if building a quick and 
simple signal source. 

===

No argument at all about other parts of the radio having their limits. PA 
performance certainly is one
of those areas. 

Bob

> On Dec 12, 2018, at 12:42 PM, Dr. Ulrich L. Rohde via time-nuts 
>  wrote:
> 
> My feeling is
> A Because of the low sunspot cycle the large signal performance of the RX is 
> less a topic, the ICOM 7851 dynamic range, synthesizer and frequency concept 
> is winning but expensive 
> B The power amplifier from 100 W to 1500 Watt need to be catching up to the 
> old Collins tube Amps with negative feedback, producing - 45 dB or better IMD 
> products.
> 
> The military amplifier are fast on , reliable , durable and expensive... 
> initially.
> 
> The noisy blower may be a bad thing.
> 
> I “only “ run 1 KW, and I am happy with it
> 
> 73 de N1UL 
> 
> Sent from my iPhone
> 
>> On Dec 12, 2018, at 10:47 AM, Bob kb8tq  wrote:
>> 
>> Hi
>> 
>> Usually on HF, the issue is large signal rejection. Phase noise very 
>> definitely 
>> gets into that part of things. Other components in the signal chain do as 
>> well.
>> Once the synthesizer is no longer the weak link in the chain, spending more
>> to improve it (vs spending on the other components) probably does not make 
>> a lot of sense. Since the synthesizer is *far* from ideal, that sort of begs 
>> the
>> question of just how troublesome the other parts are and how much better a 
>> device *could* be built.
>> 
>> This does seem to be wandering a bit from a Time related topic …..
>> 
>> It does illustrate the point that “good enough” may be way far  away from 
>> “pretty good” and yet even more distant from “as good as it gets”.  The 
>> question on any system is always “how good do you need / what are you 
>> doing?” …. 
>> 
>> Bob
>> 
>>> On Dec 12, 2018, at 8:49 AM, jimlux  wrote:
>>> 
>>> On 12/11/18 3:26 PM, Bob kb8tq wrote:
 Hi
 As I said, just how rational using these parts in a radio …. not at all 
 clear to me.
 Back when I went to school, stuff that was this noisy was not in the 
 “greatest” category.
 That was a *very* long time ago.
 Oddly enough best performance synthesizers have gotten better. (as the 
 posted
 presentations very clearly show). Just why a “high end” radio uses a less 
 than
 ideal synthesizer likely relates more to cost (even at a price of 
 thousands of dollars)
 than to anything else.
>>> 
>>> Or "good enough" performance - driving to a 3 dB NF for a HF receiver while 
>>> maintaining good strong signal performance is probably not worth it
>>> 
>>> 
 Indeed cost also drives things like GPSDO’s and GPS modules. We often are 
 not
 very eager to acknowledge that fact.
 Bob
>>> 
>>> ___
>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>> To unsubscribe, go to 
>>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
>>> and follow the instructions there.
>> 
>> 
>> ___
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>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
>> and follow the instructions there.
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Re: [time-nuts] Modern signal generators

[jimlux]

On 12/12/18 9:40 AM, Russ Ramirez wrote:

Don, you mention digital attenuators. What parts do you have experience
with? I am in the midst of a signal generator design for a club build
project. Looking at digital attenuator parts now, but many are spec'd in
the GHz range. Looking to get down to -140 dBm from +20, or as close to
this range as possible. TIA



You're looking for 160 dB of attenuation - that's hard - if something 
leaks at 100 dB down, that's 60 dB more than what you want.


If you're interested in precision phase measurements, it's even tougher, 
because a leaking signal that's "on frequency" wont necessarily make 
your level wrong, but will perturb the phase (e.g. 20 dB down spurious 
signal will make the phase wrong by 25 degrees (arccos(0.9))


It's awfully easy to get leakage that's -100 or -120dBc - backwards 
through the power supply is a favorite one. Through gaps or holes in 
enclosures. Through the braid of the coax.


At JPL we regularly do measurements of signals at <-150 dBm into 
sensitive deep space receivers, and we're obsessive about phase (since 
that's how we measure the distance to spacecraft to a gnat's eyelash). 
Historically, we found, for instance that most signal generators leak 
more through the chassis than come out the output jack at minimum level. 
  We test the receivers in a screen room, with the generators outside, 
so you get about 100dB from the screen room to help. Waveguide helps too 
(WG below cutoff is a very effective filter) and it's not too tough to 
make waveguide joints that have better than 150dB isolation to the 
outside (lap them smooth, use pins, wrap in foil tape)


Coax is always a challenge because the shields leak.


What we used to do is take an 8663 and low pass filter it real well, 
then do a low level multiply by 7 inside the screen room to get it up to 
the 7 or 8 GHz we need.  That way we can make sure that spurs and 
leakage is out of band.






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Re: [time-nuts] Modern signal generators

[Dr. Ulrich L. Rohde via time-nuts]

My feeling is
A Because of the low sunspot cycle the large signal performance of the RX is 
less a topic, the ICOM 7851 dynamic range, synthesizer and frequency concept is 
winning but expensive 
B The power amplifier from 100 W to 1500 Watt need to be catching up to the old 
Collins tube Amps with negative feedback, producing - 45 dB or better IMD 
products.

The military amplifier are fast on , reliable , durable and expensive... 
initially.

The noisy blower may be a bad thing.

I “only “ run 1 KW, and I am happy with it

73 de N1UL 

Sent from my iPhone

> On Dec 12, 2018, at 10:47 AM, Bob kb8tq  wrote:
> 
> Hi
> 
> Usually on HF, the issue is large signal rejection. Phase noise very 
> definitely 
> gets into that part of things. Other components in the signal chain do as 
> well.
> Once the synthesizer is no longer the weak link in the chain, spending more
> to improve it (vs spending on the other components) probably does not make 
> a lot of sense. Since the synthesizer is *far* from ideal, that sort of begs 
> the
> question of just how troublesome the other parts are and how much better a 
> device *could* be built.
> 
> This does seem to be wandering a bit from a Time related topic …..
> 
> It does illustrate the point that “good enough” may be way far  away from 
> “pretty good” and yet even more distant from “as good as it gets”.  The 
> question on any system is always “how good do you need / what are you 
> doing?” …. 
> 
> Bob
> 
>> On Dec 12, 2018, at 8:49 AM, jimlux  wrote:
>> 
>> On 12/11/18 3:26 PM, Bob kb8tq wrote:
>>> Hi
>>> As I said, just how rational using these parts in a radio …. not at all 
>>> clear to me.
>>> Back when I went to school, stuff that was this noisy was not in the 
>>> “greatest” category.
>>> That was a *very* long time ago.
>>> Oddly enough best performance synthesizers have gotten better. (as the 
>>> posted
>>> presentations very clearly show). Just why a “high end” radio uses a less 
>>> than
>>> ideal synthesizer likely relates more to cost (even at a price of thousands 
>>> of dollars)
>>> than to anything else.
>> 
>> Or "good enough" performance - driving to a 3 dB NF for a HF receiver while 
>> maintaining good strong signal performance is probably not worth it
>> 
>> 
>>> Indeed cost also drives things like GPSDO’s and GPS modules. We often are 
>>> not
>>> very eager to acknowledge that fact.
>>> Bob
>> 
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Re: [time-nuts] Modern signal generators

[Russ Ramirez]

Don, you mention digital attenuators. What parts do you have experience
with? I am in the midst of a signal generator design for a club build
project. Looking at digital attenuator parts now, but many are spec'd in
the GHz range. Looking to get down to -140 dBm from +20, or as close to
this range as possible. TIA

Russ

On Wed, Dec 12, 2018 at 11:00 AM  wrote:

>
> Rick: I've spent some time with the dds blocks. We found them to
> generate lots of low level spurs, making lots of "birdies" when used as
> local oscillators in receivers.
> We had better results using:
> https://www.silabs.com/products/timing/oscillators.
>
> These may be used with GPSDO clocks for accuracy, and generate less
> noise. Cost is about the same; there are two or three sources for
> breakout units. The clock sources do have to be 25/27 MHz, those from
> Leo Bodnar, or use an OCXO.  Digital attenuators are also available; all
> this can be run from an Arduino with oled or other readouts, libraries
> abound. And for quick and fancy GUI, on a pc, use MakerPlot.
> Just $.02
> Don
>
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Re: [time-nuts] Modern signal generators

[Bob kb8tq]

Hi

Usually on HF, the issue is large signal rejection. Phase noise very definitely 
gets into that part of things. Other components in the signal chain do as well.
Once the synthesizer is no longer the weak link in the chain, spending more
to improve it (vs spending on the other components) probably does not make 
a lot of sense. Since the synthesizer is *far* from ideal, that sort of begs the
question of just how troublesome the other parts are and how much better a 
device *could* be built.

This does seem to be wandering a bit from a Time related topic …..

It does illustrate the point that “good enough” may be way far  away from 
“pretty good” and yet even more distant from “as good as it gets”.  The 
question on any system is always “how good do you need / what are you 
doing?” …. 

Bob

> On Dec 12, 2018, at 8:49 AM, jimlux  wrote:
> 
> On 12/11/18 3:26 PM, Bob kb8tq wrote:
>> Hi
>> As I said, just how rational using these parts in a radio …. not at all 
>> clear to me.
>> Back when I went to school, stuff that was this noisy was not in the 
>> “greatest” category.
>> That was a *very* long time ago.
>> Oddly enough best performance synthesizers have gotten better. (as the posted
>> presentations very clearly show). Just why a “high end” radio uses a less 
>> than
>> ideal synthesizer likely relates more to cost (even at a price of thousands 
>> of dollars)
>> than to anything else.
> 
> Or "good enough" performance - driving to a 3 dB NF for a HF receiver while 
> maintaining good strong signal performance is probably not worth it
> 
> 
>> Indeed cost also drives things like GPSDO’s and GPS modules. We often are not
>> very eager to acknowledge that fact.
>> Bob
> 
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Re: [time-nuts] Modern signal generators

[jimlux]

On 12/11/18 3:26 PM, Bob kb8tq wrote:

Hi

As I said, just how rational using these parts in a radio …. not at all clear 
to me.
Back when I went to school, stuff that was this noisy was not in the “greatest” 
category.
That was a *very* long time ago.

Oddly enough best performance synthesizers have gotten better. (as the posted
presentations very clearly show). Just why a “high end” radio uses a less than
ideal synthesizer likely relates more to cost (even at a price of thousands of 
dollars)
than to anything else.


Or "good enough" performance - driving to a 3 dB NF for a HF receiver 
while maintaining good strong signal performance is probably not worth it





Indeed cost also drives things like GPSDO’s and GPS modules. We often are not
very eager to acknowledge that fact.

Bob



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Re: [time-nuts] Modern signal generators

[Bob kb8tq]

Hi

As I said, just how rational using these parts in a radio …. not at all clear 
to me.
Back when I went to school, stuff that was this noisy was not in the “greatest” 
category.
That was a *very* long time ago.

Oddly enough best performance synthesizers have gotten better. (as the posted 
presentations very clearly show). Just why a “high end” radio uses a less than 
ideal synthesizer likely relates more to cost (even at a price of thousands of 
dollars)
than to anything else.

Indeed cost also drives things like GPSDO’s and GPS modules. We often are not
very eager to acknowledge that fact. 

Bob

> On Dec 11, 2018, at 5:24 PM, Gerhard Hoffmann  wrote:
> 
> 
> Am 11.12.18 um 20:30 schrieb jimlux:
>> On 12/11/18 10:23 AM, Richard (Rick) Karlquist wrote:
>>> 
>>> 
>>> On 12/11/2018 9:13 AM, djl wrote:
 Rick: I've spent some time with the dds blocks. We found them to generate 
 lots of low level spurs, making lots of "birdies" when used as local 
 oscillators in receivers.
 We had better results using:
 https://www.silabs.com/products/timing/oscillators.
 
>>> 
>>> I was talking about making a programmable frequency synthesizer
>>> with a DDS, to use as a general purpose signal generator.
>>> 
>>> A silabs part functions exactly the same as a crystal oscillator
>>> once it receives its one-time programming at the factory, AFAIK.
>>> 
>> 
>> Most of the Silabs parts are available in an  I2C programmable version 
>> rather than the factory programmed flavor.
>> 
> Yes, but they all have in common that their oh! so good jitter values
> 
> exclude the first 12 or even 50 KHz from the carrier. With enough DSP
> 
> you can shove a lot of dirt towards the first 12 KHz: look, ma, no birdies.
> 
> Those without an E5052B or FSUP won't notice, and the OC-48 or OC-192
> 
> or other telecom target market won't care anyway. But the birdies are not
> 
> magically gone, they were squashed under the DSP steam roller.
> 
> 
> The nagging DDS birdies happen when you are close, but not exactly on
> 
> a subharmonic of the clock frequency. In an avionics com transceiver I got
> 
> easily rid of them by using 2 clock frequencies and switching as best
> 
> for the channel. With this DO-178? stuff you are punished for oscillator
> 
> birdies when you try to make the receiver more sensitive. :-(
> 
> 
> Ulrich and DJ7VY and some others have shown us >40 years ago how to
> 
> do shortwave/VHF receivers (hey, I was still in school then, and it gave me
> 
> the kick towards RF engineering) and ring mixers still have their place, but
> 
> not in the input of a ham rig. There should be a 16 bit 150MHz+ ADC after
> 
> the tuned preselector, and the rest is digital. I have published a
> 
> synthesiseable sine / cos table on opencores.org a decade ago. The test
> 
> bed is a DDS. just fill in the resolution you want and buy an el cheapo Xilinx
> 
> Spartan FPGA to give it a home, and then filter & decimate the hell out of
> 
> your ADC data. No more analog LO. We now have things like AD9172,
> 
> ADC12J4000 and AD9625 to play with. That's the new frontier.
> 
> 
> Now that I have your attention I'm currently interested into 1/f noise,
> 
> or, more precisely, in how to avoid it. Is there anything known on 1/f
> 
> in FETs as used in switches, such as choppers? Is there more than thermal
> 
> noise of the channel? There is a paper of the Univ of Twente that suggests 
> there
> 
> is some time delay when fets are turned on until the trap locations turn 
> active.
> 
> That could be a nice by-effect.
> 
> Even van der Ziel and Cobbold are silent about that.
> 
> 
> cheers,
> 
> Gerhard, DK4XP
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
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Re: [time-nuts] Modern signal generators

[Ulrich Rohde via time-nuts]

yes 
 
In a message dated 12/11/2018 5:29:23 PM Eastern Standard Time, 
k8yumdoo...@gmail.com writes:

 
 Ulrich,

Is it OK for us to forward the URL for your "Noise" paper to others
outside the time-nuts group?

Thanks,

Dana K8YUM


On Tue, Dec 11, 2018 at 9:24 AM Ulrich Rohde via time-nuts <
time-nuts@lists.febo.com> wrote:

>
> https://badw.de/fileadmin/members/R/3685/6_4_18_UNI_BW_June18-safe.pdf
> ___
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Re: [time-nuts] Modern signal generators

[Bob Albert via time-nuts]

 You can solve the spur problem by using the signal to lock an oscillator.  
Some added phase noise but the oscillator can be very pure otherwise.  Many 
years ago I wrote an unsuccessful proposal for a synthesizer using that idea, 
since the spectral purity spec was too tight to use synthesizer output directly.
Frequency agility is another issue, easily solved in a synth but not so in a 
locked oscillator.
Bob
On Tuesday, December 11, 2018, 2:29:23 PM PST, Dana Whitlow 
 wrote:  
 
 Ulrich,

Is it OK for us to forward the URL for your "Noise" paper to others
outside the time-nuts group?

Thanks,

Dana  K8YUM


On Tue, Dec 11, 2018 at 9:24 AM Ulrich Rohde via time-nuts <
time-nuts@lists.febo.com> wrote:

>
> https://badw.de/fileadmin/members/R/3685/6_4_18_UNI_BW_June18-safe.pdf
> ___
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Re: [time-nuts] Modern signal generators

[Dana Whitlow]

Ulrich,

Is it OK for us to forward the URL for your "Noise" paper to others
outside the time-nuts group?

Thanks,

Dana   K8YUM


On Tue, Dec 11, 2018 at 9:24 AM Ulrich Rohde via time-nuts <
time-nuts@lists.febo.com> wrote:

>
> https://badw.de/fileadmin/members/R/3685/6_4_18_UNI_BW_June18-safe.pdf
> ___
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Re: [time-nuts] Modern signal generators

[Gerhard Hoffmann]

Am 11.12.18 um 20:30 schrieb jimlux:

On 12/11/18 10:23 AM, Richard (Rick) Karlquist wrote:



On 12/11/2018 9:13 AM, djl wrote:
Rick: I've spent some time with the dds blocks. We found them to 
generate lots of low level spurs, making lots of "birdies" when used 
as local oscillators in receivers.

We had better results using:
https://www.silabs.com/products/timing/oscillators.



I was talking about making a programmable frequency synthesizer
with a DDS, to use as a general purpose signal generator.

A silabs part functions exactly the same as a crystal oscillator
once it receives its one-time programming at the factory, AFAIK.



Most of the Silabs parts are available in an  I2C programmable version 
rather than the factory programmed flavor.



Yes, but they all have in common that their oh! so good jitter values

exclude the first 12 or even 50 KHz from the carrier. With enough DSP

you can shove a lot of dirt towards the first 12 KHz: look, ma, no birdies.

Those without an E5052B or FSUP won't notice, and the OC-48 or OC-192

or other telecom target market won't care anyway. But the birdies are not

magically gone, they were squashed under the DSP steam roller.


The nagging DDS birdies happen when you are close, but not exactly on

a subharmonic of the clock frequency. In an avionics com transceiver I got

easily rid of them by using 2 clock frequencies and switching as best

for the channel. With this DO-178? stuff you are punished for oscillator

birdies when you try to make the receiver more sensitive. :-(


Ulrich and DJ7VY and some others have shown us >40 years ago how to

do shortwave/VHF receivers (hey, I was still in school then, and it gave me

the kick towards RF engineering) and ring mixers still have their place, but

not in the input of a ham rig. There should be a 16 bit 150MHz+ ADC after

the tuned preselector, and the rest is digital. I have published a

synthesiseable sine / cos table on opencores.org a decade ago. The test

bed is a DDS. just fill in the resolution you want and buy an el cheapo 
Xilinx


Spartan FPGA to give it a home, and then filter & decimate the hell out of

your ADC data. No more analog LO. We now have things like AD9172,

ADC12J4000 and AD9625 to play with. That's the new frontier.


Now that I have your attention I'm currently interested into 1/f noise,

or, more precisely, in how to avoid it. Is there anything known on 1/f

in FETs as used in switches, such as choppers? Is there more than thermal

noise of the channel? There is a paper of the Univ of Twente that 
suggests there


is some time delay when fets are turned on until the trap locations turn 
active.


That could be a nice by-effect.

Even van der Ziel and Cobbold are silent about that.


cheers,

Gerhard, DK4XP











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Re: [time-nuts] Modern signal generators

[Richard (Rick) Karlquist]

On 12/11/2018 11:30 AM, jimlux wrote:



Most of the Silabs parts are available in an  I2C programmable version 
rather than the factory programmed flavor.




That's for clarifying that.  The web site is hard
to navigate.  I see that the phase noise is not
even close to an HP 8662 and the VCXO versions
(not surprisingly) are noisier.  The phase noise
of the XO is worse than the worst Crystek XO,
and the VCXO is worse than the worst Crystek VCXO.
The modulation BW is only 10 kHz, and you can't lock
them to an external reference frequency.  I suspect
the chip has an onboard oven providing both fine tuning
and temperature correction.  Nothing especially profound
about this architecture.  It is not clear from the block
diagram if the "DCO" refers to a DDS, or whether there
is some frac-N mechanism.

The performance is in the general ballpark of the one chip
synthesizers with on board VCOs when those are locked to
a clean reference.

Rick

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Re: [time-nuts] Modern signal generators

[jimlux]

On 12/11/18 10:23 AM, Richard (Rick) Karlquist wrote:



On 12/11/2018 9:13 AM, djl wrote:
Rick: I've spent some time with the dds blocks. We found them to 
generate lots of low level spurs, making lots of "birdies" when used 
as local oscillators in receivers.

We had better results using:
https://www.silabs.com/products/timing/oscillators.



I was talking about making a programmable frequency synthesizer
with a DDS, to use as a general purpose signal generator.

A silabs part functions exactly the same as a crystal oscillator
once it receives its one-time programming at the factory, AFAIK.



Most of the Silabs parts are available in an  I2C programmable version 
rather than the factory programmed flavor.




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Re: [time-nuts] Modern signal generators

[Bob kb8tq]

Hi

There are I2C versions that can be set to “any frequency”. That’s what people 
are using 
for synthesizers in radios. Again - one can debate just how good an idea this 
all is. 

Bob

> On Dec 11, 2018, at 1:23 PM, Richard (Rick) Karlquist  
> wrote:
> 
> 
> 
> On 12/11/2018 9:13 AM, djl wrote:
>> Rick: I've spent some time with the dds blocks. We found them to generate 
>> lots of low level spurs, making lots of "birdies" when used as local 
>> oscillators in receivers.
>> We had better results using:
>> https://www.silabs.com/products/timing/oscillators.
> 
> I was talking about making a programmable frequency synthesizer
> with a DDS, to use as a general purpose signal generator.
> 
> A silabs part functions exactly the same as a crystal oscillator
> once it receives its one-time programming at the factory, AFAIK.
> 
> Of course a crystal oscillator has better spectral purity than
> a frequency synthesizer.  But it doesn't make a signal generator.
> 
> Am I missing something?
> 
> BTW, you can do even better than Silabs with an actual crystal
> oscillator such as those made by Crystek.
> 
> Rick
> 
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Re: [time-nuts] Modern signal generators

[Richard (Rick) Karlquist]

On 12/11/2018 9:13 AM, djl wrote:
Rick: I've spent some time with the dds blocks. We found them to 
generate lots of low level spurs, making lots of "birdies" when used as 
local oscillators in receivers.

We had better results using:
https://www.silabs.com/products/timing/oscillators.



I was talking about making a programmable frequency synthesizer
with a DDS, to use as a general purpose signal generator.

A silabs part functions exactly the same as a crystal oscillator
once it receives its one-time programming at the factory, AFAIK.

Of course a crystal oscillator has better spectral purity than
a frequency synthesizer.  But it doesn't make a signal generator.

Am I missing something?

BTW, you can do even better than Silabs with an actual crystal
oscillator such as those made by Crystek.

Rick

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Re: [time-nuts] Modern signal generators

[Bob kb8tq]

Hi

I don’t know if it’s expected / surprising / alarming, but a lot of pretty well 
respected 
amateur transceivers have the SiLabs parts buried in the heart of their 
“synthesizer”
section. Cost (obviously) is an issue in any design. That said, they seem to be 
“good
enough” that the designers don’t go much further. 

Bob

> On Dec 11, 2018, at 12:13 PM, djl  wrote:
> 
> Rick: I've spent some time with the dds blocks. We found them to generate 
> lots of low level spurs, making lots of "birdies" when used as local 
> oscillators in receivers.
> We had better results using:
> https://www.silabs.com/products/timing/oscillators.
> 
> These may be used with GPSDO clocks for accuracy, and generate less noise. 
> Cost is about the same; there are two or three sources for breakout units. 
> The clock sources do have to be 25/27 MHz, those from Leo Bodnar, or use an 
> OCXO.  Digital attenuators are also available; all this can be run from an 
> Arduino with oled or other readouts, libraries abound. And for quick and 
> fancy GUI, on a pc, use MakerPlot.
> Just $.02
> Don
> 
> On 2018-12-11 09:46, Richard (Rick) Karlquist wrote:
>> Another gold mine.  I used to work for Agilent/Keysight so I
>> am very familiar with their signal generators.  It
>> will be interesting to see the R&S viewpoint.  The DDS
>> stuff is very valuable.  I have been considering using
>> a DDS eval board with a low noise 1 GHZ reference to
>> make a poor man's signal generator for my home lab.
>> Your paper will be required reading.  I suspect a lot
>> of time nuts are in a similar situation as me.
>> Thanks.
>> Rick
>> On 12/11/2018 7:23 AM, Ulrich Rohde via time-nuts wrote:
>>>  https://badw.de/fileadmin/members/R/3685/6_4_18_UNI_BW_June18-safe.pdf
>>> ___
>>> time-nuts mailing list -- time-nuts@lists.febo.com
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>> and follow the instructions there.
> 
> -- 
> Dr. Don Latham  AJ7LL
> PO Box 404, Frenchtown, MT, 59834
> VOX: 406-626-4304
> 
> 
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Re: [time-nuts] Modern signal generators

[djl]

Rick: I've spent some time with the dds blocks. We found them to 
generate lots of low level spurs, making lots of "birdies" when used as 
local oscillators in receivers.

We had better results using:
https://www.silabs.com/products/timing/oscillators.

These may be used with GPSDO clocks for accuracy, and generate less 
noise. Cost is about the same; there are two or three sources for 
breakout units. The clock sources do have to be 25/27 MHz, those from 
Leo Bodnar, or use an OCXO.  Digital attenuators are also available; all 
this can be run from an Arduino with oled or other readouts, libraries 
abound. And for quick and fancy GUI, on a pc, use MakerPlot.

Just $.02
Don

On 2018-12-11 09:46, Richard (Rick) Karlquist wrote:

Another gold mine.  I used to work for Agilent/Keysight so I
am very familiar with their signal generators.  It
will be interesting to see the R&S viewpoint.  The DDS
stuff is very valuable.  I have been considering using
a DDS eval board with a low noise 1 GHZ reference to
make a poor man's signal generator for my home lab.
Your paper will be required reading.  I suspect a lot
of time nuts are in a similar situation as me.

Thanks.

Rick

On 12/11/2018 7:23 AM, Ulrich Rohde via time-nuts wrote:
  
https://badw.de/fileadmin/members/R/3685/6_4_18_UNI_BW_June18-safe.pdf

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--
Dr. Don Latham  AJ7LL
PO Box 404, Frenchtown, MT, 59834
VOX: 406-626-4304


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and follow the instructions there.

Re: [time-nuts] Modern signal generators

[Richard (Rick) Karlquist]

Another gold mine.  I used to work for Agilent/Keysight so I
am very familiar with their signal generators.  It
will be interesting to see the R&S viewpoint.  The DDS
stuff is very valuable.  I have been considering using
a DDS eval board with a low noise 1 GHZ reference to
make a poor man's signal generator for my home lab.
Your paper will be required reading.  I suspect a lot
of time nuts are in a similar situation as me.

Thanks.

Rick

On 12/11/2018 7:23 AM, Ulrich Rohde via time-nuts wrote:
  
https://badw.de/fileadmin/members/R/3685/6_4_18_UNI_BW_June18-safe.pdf

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