Re: Si5351 Frequency Calculation

Shirley Dulcey KE1L

Although the specified range of operation of the Si5351A calls for a PLL frequency between 600 and 900 MHz, the chip will work with PLL frequencies outside that range. People have gotten output frequencies near 300 MHz out of the chip (the specified maximum is 200 MHz), which requires a PLL frequency well above 900 MHz. (The nanoVNA uses that to achieve more frequency range.) Frequencies below 600 MHz are useful to generate quadrature clocks at lower frequencies (the QCX uses that technique on 80 meters) or to extend the minimum frequency lower into the audio range.

When you operate the Si5351A outside its specifications, the results are not guaranteed. Some chips might go to higher frequencies than others, and the supply voltage may matter. (Just like your CPU, using more voltage will probably allow the Si5351A to reach higher frequencies.) Power consumption may rise above the specified limit so heat could become a problem, especially if you are using it at ambient temperature well above normal room temperature. The chip may not meet its jitter specification, which will mean more phase noise on your local oscillator. The waveform of the output has less and less resemblance to the desired square wave output as frequency increases.

Warnings aside, the Si5351A seems to work well enough at frequencies outside its specs to be useful for a number of applications.

On Sun, Oct 11, 2020 at 8:42 AM KI7MWA via groups.io <entilleser=yahoo.com@groups.io> wrote:
I've been playing with a 5351 breakout board & have a question about the way the frequency is calculated, and its limitations.

Setting the PLL frequency is based on a crystal frequency (nominally 25 or 27 MHz) and a (three part) multiplier.  In the simplest case, the multiplier can be in the range (15...90), which, for a 25MHz crystal, would imply a (nominal) range of 375MHz to 2250MHz.

In various discussions, it is noted that the PLL frequency is (should be?) limited to a range of 600-900 MHz, implying a multiplier range of 24-36, given a 25MHz crystal.

I make the assumption that multiplier values outside this 24-36 range are there to enable the use of crystals (or other frequency sources) other than the nominal 25/27MHz.

Or is there something I'm missing?

Re: Polyphase network PCB question

Alessandro Santucci

TNX Mike,
I was looking to know what id number are them, I pointed them on the pcb as the manual is really clear, but I should need the identification.

HI

Best regards and 73

Alex I5SKK

Si5351 Frequency Calculation

KI7MWA

I've been playing with a 5351 breakout board & have a question about the way the frequency is calculated, and its limitations.

Setting the PLL frequency is based on a crystal frequency (nominally 25 or 27 MHz) and a (three part) multiplier.  In the simplest case, the multiplier can be in the range (15...90), which, for a 25MHz crystal, would imply a (nominal) range of 375MHz to 2250MHz.

In various discussions, it is noted that the PLL frequency is (should be?) limited to a range of 600-900 MHz, implying a multiplier range of 24-36, given a 25MHz crystal.

I make the assumption that multiplier values outside this 24-36 range are there to enable the use of crystals (or other frequency sources) other than the nominal 25/27MHz.

Or is there something I'm missing?

Re: Si5351A Synthesizer Module

Podolsky A <w8du@...>

Scott:
I would very much be interested in the 5351 synth design you are referring to. Hopefully you can find it without too much fuss.
Tnx de Arnie W8DU

Re: 50 Watt Amp resistors color coding different than parts list

Shirley Dulcey KE1L

You got that backwards. The five band resistors have a closer tolerance (usually 1%) than the four band ones (usually 5%). They're also metal film rather than carbon film.

The QCX also uses 1% metal film resistors. There are a few places in the circuit where the more precise resistors matter, like the phase shifting filters; more accurate components means better performance. Metal film resistors also generate less self-noise, which helps keep the noise figure of the first audio stage down. (That's the one where it matters; the noise figure of later stages is far less important.) Hans could use a mix of 1% and 5% resistors, but it's less confusing to builders if all the resistors use the same type of color code.

If he were planning to mass-produce the QCX and have a million of them made in a factory, he might have gone with two different types of parts. Consumer electronics companies have specialists called production engineers; their job is to squeeze pennies out of the BoM of devices to improve the company's bottom line. That includes things like loosening the tolerances of components where it doesn't matter, and figuring out how many of the bypass capacitors can be removed from a design without making the device unreliable. Reducing the BoM by a mere 10 cents matters if you're going to make a million units: that's a savings of \$100,000. Products that get small runs, like most amateur radio products, never get production-engineered; you would never earn back the cost of the engineering work.

On Sat, Oct 10, 2020 at 9:03 PM Dave via groups.io <dsdzen-AE9Q=yahoo.com@groups.io> wrote:
Yes, I went through the same struggle on trying to figure what was going on.  The values were the same as stated in the manual but the tolerances were bigger, so I guess they were good enough.  The resistors in the kit were 5-band color codes and the codes in the manual were for 4 band.

My 40m amp works great, so all is well!

Dave, AE9Q

Re: Si5351A Synthesizer Module

Scott McDonald

Here's some interesting work that could help you with the interface Dick.

There's also a fella on the drake groups.io board that has a file with a 5351 synthesizer design for use as an FS-4, I'll see if I can find that for you, I'm sure it's more directly on point.

Scott ka9p

-----Original Message-----
From: Dick <w1ksz@...>
To: QRPLabs@groups.io <qrplabs@groups.io>
Sent: Sat, Oct 10, 2020 9:24 pm
Subject: Re: [QRPLabs] Si5351A Synthesizer Module

I tried direct, but looking at the schematic of the FS-4, I think
I'll add a .001uF cap in series and try again.

73, Dick, W1KSZ

From: QRPLabs@groups.io <QRPLabs@groups.io> on behalf of Scott McDonald via groups.io <ka9p@...>
Sent: Saturday, October 10, 2020 6:11 PM
To: QRPLabs@groups.io <QRPLabs@groups.io>
Subject: Re: [QRPLabs] Si5351A Synthesizer Module

Hi Dick,

How are you connected to the crystal socket (or mixer), thru a cap or?

I can check one on an R4C if it will help.

Scott Ka9p

Make something good happen!

On Oct 10, 2020, at 5:05 PM, Dick <w1ksz@...> wrote:

﻿
How much of a load can you put on one of these modules ?

I tried using it as a Crystal replacement in a Drake R-4B Receiver, but

It seems like it's doable, but so far no luck.

Any suggestions ?

Thanks, Dick, W1KSZ

Re: Si5351A Synthesizer Module

Dick <w1ksz@...>

I tried direct, but looking at the schematic of the FS-4, I think
I'll add a .001uF cap in series and try again.

73, Dick, W1KSZ

From: QRPLabs@groups.io <QRPLabs@groups.io> on behalf of Scott McDonald via groups.io <ka9p@...>
Sent: Saturday, October 10, 2020 6:11 PM
To: QRPLabs@groups.io <QRPLabs@groups.io>
Subject: Re: [QRPLabs] Si5351A Synthesizer Module

Hi Dick,

How are you connected to the crystal socket (or mixer), thru a cap or?

I can check one on an R4C if it will help.

Scott Ka9p

Make something good happen!

On Oct 10, 2020, at 5:05 PM, Dick <w1ksz@...> wrote:

﻿
How much of a load can you put on one of these modules ?

I tried using it as a Crystal replacement in a Drake R-4B Receiver, but

It seems like it's doable, but so far no luck.

Any suggestions ?

Thanks, Dick, W1KSZ

Re: QCX+ 40M not Rx and Tx

Ian VA7ITM

From the photos it looks like one leg of Q1 and one leg of C25 have not been soldered??

Ian VA7ITM

Re: Si5351A Synthesizer Module

Scott McDonald

Hi Dick,

How are you connected to the crystal socket (or mixer), thru a cap or?

I can check one on an R4C if it will help.

Scott Ka9p

Make something good happen!

On Oct 10, 2020, at 5:05 PM, Dick <w1ksz@...> wrote:

﻿
How much of a load can you put on one of these modules ?

I tried using it as a Crystal replacement in a Drake R-4B Receiver, but

It seems like it's doable, but so far no luck.

Any suggestions ?

Thanks, Dick, W1KSZ

Re: Si5351A Synthesizer Module

Don VE3IDS

I tried Greg's circuit and couldn't get it to work and another ham built it up and confirmed he couldn't get it to work either. That's when I went for Diz's kit. Worked FB

73 Don ve3ids

On Sat., Oct. 10, 2020, 8:53 p.m. ajparent1/KB1GMX, <kb1gmx@...> wrote:
The si5351 can do up to around 13dbm into 50 ohms.

The problem most tube circuits need very little power but the
voltage required is more like 10V across 10K ohms, sometimes higher.

A 1 or 2 transistor buffer with high impedance output (try 1:9 transformer).

Note greg latta(aa8V) using that buffer limits you to about 6-7 V out, he shows
a 1:2 transformer to get the required voltage.   Kits and parts mp may work better
in some cases with a matching (50 ohms to higher) transformer.

Allison
-------------------------------
No private email, it goes to a bit bucket due address harvesting

Re: 50 Watt Amp resistors color coding different than parts list

Dave AE9Q

Yes, I went through the same struggle on trying to figure what was going on.  The values were the same as stated in the manual but the tolerances were bigger, so I guess they were good enough.  The resistors in the kit were 5-band color codes and the codes in the manual were for 4 band.

My 40m amp works great, so all is well!

Dave, AE9Q

Re: 50 Watt Amp resistors color coding different than parts list

Brian N7BKV

Another thing not to overlook is get the most current version of the manual.  Which as of today is version 1.00p.  dated October 5.  It corrects some of, but not all of what this thread discusses.  I was working from a June version.  Small details have been corrected.  Some, but not all of the resistor color makings.

On Sat, Oct 10, 2020 at 05:38 PM, Mike Besemer - WM4B wrote:

I do the same thing except I used a muffin pan and mark things with sticky notes or masking tape.

If the kit isn’t too complex, I even go through the manual and arrange parts in the muffin pan in their order of use.  Of course, I always recheck the part before installation, but that extra bit of prep time, sure makes the build go quickly.

Mike

WM4B

Re: Si5351A Synthesizer Module

ajparent1/KB1GMX

The si5351 can do up to around 13dbm into 50 ohms.

The problem most tube circuits need very little power but the
voltage required is more like 10V across 10K ohms, sometimes higher.

A 1 or 2 transistor buffer with high impedance output (try 1:9 transformer).

Note greg latta(aa8V) using that buffer limits you to about 6-7 V out, he shows
a 1:2 transformer to get the required voltage.   Kits and parts mp may work better
in some cases with a matching (50 ohms to higher) transformer.

Allison
-------------------------------
No private email, it goes to a bit bucket due address harvesting

Re: 50 Watt Amp resistors color coding different than parts list

Mike Besemer - WM4B

I do the same thing except I used a muffin pan and mark things with sticky notes or masking tape.

If the kit isn’t too complex, I even go through the manual and arrange parts in the muffin pan in their order of use.  Of course, I always recheck the part before installation, but that extra bit of prep time, sure makes the build go quickly.

Mike

WM4B

From: QRPLabs@groups.io [mailto:QRPLabs@groups.io] On Behalf Of Brian N7BKV
Sent: Saturday, October 10, 2020 8:33 PM
To: QRPLabs@groups.io
Subject: Re: [QRPLabs] 50 Watt Amp resistors color coding different than parts list

I feel your pain.  When I inventory the kit  I write on the paper tab what the info on the part is after I figure it out.  And for the one's and two's etc I tape them to a card and write the info next to them.  That way when I proceed through the manual I don't have to paw back through the bags.  Just a build tip for anyone slower than me on this stuff.  Took me a while to figure that out.

On Sat, Oct 10, 2020 at 05:25 PM, Mike Besemer - WM4B wrote:

Ha!  Working on my amp kit today and I had to get out my soldering microscope to read the values on the capacitors!

Re: 50 Watt Amp resistors color coding different than parts list

Brian N7BKV

I feel your pain.  When I inventory the kit  I write on the paper tab what the info on the part is after I figure it out.  And for the one's and two's etc I tape them to a card and write the info next to them.  That way when I proceed through the manual I don't have to paw back through the bags.  Just a build tip for anyone slower than me on this stuff.  Took me a while to figure that out.

On Sat, Oct 10, 2020 at 05:25 PM, Mike Besemer - WM4B wrote:
Ha!  Working on my amp kit today and I had to get out my soldering microscope to read the values on the capacitors!

Re: 50 Watt Amp resistors color coding different than parts list

Brian N7BKV

Yep, that I have noticed, Curt.  But what really threw me were the "gold" bands in the multiplier 4th position.  Hmm.  Not accustomed to that. Not on my chart.

Brian

On Sat, Oct 10, 2020 at 05:19 PM, @CurtisM wrote:

these resistors use more bands than we may be used to - and it always isn't obvious to me which end the left one

Re: 50 Watt Amp resistors color coding different than parts list

Mike Besemer - WM4B

Ha!  Working on my amp kit today and I had to get out my soldering microscope to read the values on the capacitors!

Mike

WM4B

From: QRPLabs@groups.io [mailto:QRPLabs@groups.io] On Behalf Of Shane Justice
Sent: Saturday, October 10, 2020 8:14 PM
To: QRPLabs
Subject: Re: [QRPLabs] 50 Watt Amp resistors color coding different than parts list

Brian,

My eyes are old and I am partly red/green color blind, so I run every resistor on my DVM to determine the values. (I do the same with the capacitors and inductors to. Make sure they measure what the markings say, and some markings are missing {!!!})...

I was unaware there has been a change to the color code- what changes have you seen???

73,

Shane

On Oct 10, 2020 at 17:04, Brian N7BKV <cl@...> wrote:

Regarding the 50 Watt Amp kit:
OK, all is well in the end, but the parts list color coding is different than the actual resistors supplied.
However, the values on the parts list are correct for the values of the actual colors on the resisters.
It just took an hour to sort it out and get out the Resister Color Code Chart and chase this issue down.
Anyone else notice this?
Or am I from the dark ages using an out of date Color Code chart?

Anyway, I got it all sorted out and ready to wind the toroids and stuff the board!

Brian N
N7BKV

Re: 50 Watt Amp resistors color coding different than parts list

Brian N7BKV

I was just musing if there was a code change that I missed.  Seems strange if there was.  But I was surprised the kit came with the parts coded differently from the instruction parts list.  Hmmm.  Maybe I just missed a note somewhere in the other build caveats online.

Oh, well.  No harm done.  But I like your idea of metering every part.  Good idea.  Reading those blue caps  took a loupe and bright sunlight.  Whew!  Glad they were all correct.

73
Brian N

On Sat, Oct 10, 2020 at 05:14 PM, Shane Justice wrote:

I was unaware there has been a change to the color code- what changes have you seen???

73,
Shane

Re: Si5351A Synthesizer Module

@CurtisM

also AA8V website has a nice circuit (and explanation) to drive a tube application - check out Greg Latta website.

PS - my first rig I used at high school club was TR4B.  no my own personal gear then was nothing so exotic.

73 curt

Re: 50 Watt Amp resistors color coding different than parts list

@CurtisM

Brian

these resistors use more bands than we may be used to - and it always isn't obvious to me which end the left one (for those of us that read left to right).

yes proceed with care to ID the resistors and verify them with your ohmmeter.

73 curt

 11601 - 11620 of 64893