Date   
Re: Maximum Power using FR4 board ?

Murray Niman
 

Lots more if you happen to use 1oz copper clad, rather than the more usual 0.5 or 0.25oz

73

  Murray

Re: Maximum Power using FR4 board ?

Gordon REASON
 

If .............. you have a good load , 100 W should be ok .............

Some years back I made and  testee , low power , a 2,7 Ghz coupler .

The customer put 400 watts through it , and it melted ...............!

On 14 June 2019 at 17:56 simonchettle <simon@...> wrote:

This is  a simple question what is the maximum power anyone would risk using a 1/4 length strip line on FR4 on 23cms ? 
 
Why because my metal working tools and skills are close zero and I am thinking of building a Wilkinson divider. 
 
I am thinking of combining two power amplifiers each of circa 100 W  O/P. 
 
 
Cheers
 
 
Simon
 
G8ATB
 


 


 

Re: Maximum Power using FR4 board ?

John Worsnop
 

So much depends on where the line is in the circuit, the dielectric thickness and the type of FR4. At RF, not all FR4 is the same! The thing is the the power density in the dielectric. The reason I used low loss RF35 in my 45W pa was the original FR4 version cooked the output line. In contrast, designs by  Goran AD6IW I've seen work perfectly well at similar powers. That may of course just be a reflection on Goran's design skills compared to mine!

Stick to proper microwave materials for power if you can.

73 John

On Sat, 15 Jun 2019, 01:01 Gordon REASON via Groups.Io, <gordonj.reason=virgin.net@groups.io> wrote:

If .............. you have a good load , 100 W should be ok .............

Some years back I made and  testee , low power , a 2,7 Ghz coupler .

The customer put 400 watts through it , and it melted ...............!

On 14 June 2019 at 17:56 simonchettle <simon@...> wrote:

This is  a simple question what is the maximum power anyone would risk using a 1/4 length strip line on FR4 on 23cms ? 
 
Why because my metal working tools and skills are close zero and I am thinking of building a Wilkinson divider. 
 
I am thinking of combining two power amplifiers each of circa 100 W  O/P. 
 
 
Cheers
 
 
Simon
 
G8ATB
 


 


 

RAL

SAM JEWELL
 

Folks,
I have a number of 24GHz equipment items that I wish to dispose of at RAL.
Amongst these I have an unused Millitech 2  - 2.5W PA, 48cm Procom dish with Procom 24GHz feed fitted, 26.5GHz APC3.5 (SMA like) relays, one of those nice ZL sourced waveguide switches, several other waveguide items. In addition, I have decided I won’t be getting going on 47GHz again any time soon, so I have a number of 47GHz items available, including a number of Kuhne commercial items.
I’ll bring these items tomorrow, together with the WA5VJB PCB antennas. I don’t plan to bring any kits, but if anyone wants to reserve anything in particular, I will endeavour to bring it along.

73 de Sam, G4DDK

Re: Maximum Power using FR4 board ?

John Quarmby
 

I found 50W of 1296MHz through a 50 ohm stripline on FR4 cooked the board and discoloured it over time. Why not use suspended microstrip with air dielectric, that would avoid the problem entirely at any reasonable power level.

73

John G3XDY 



Sent from my Samsung Galaxy smartphone.

-------- Original message --------
From: John Worsnop <johnworsnop@...>
Date: 15/06/2019 08:28 (GMT+00:00)
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Maximum Power using FR4 board ?

So much depends on where the line is in the circuit, the dielectric thickness and the type of FR4. At RF, not all FR4 is the same! The thing is the the power density in the dielectric. The reason I used low loss RF35 in my 45W pa was the original FR4 version cooked the output line. In contrast, designs by  Goran AD6IW I've seen work perfectly well at similar powers. That may of course just be a reflection on Goran's design skills compared to mine!

Stick to proper microwave materials for power if you can.

73 John

On Sat, 15 Jun 2019, 01:01 Gordon REASON via Groups.Io, <gordonj.reason=virgin.net@groups.io> wrote:

If .............. you have a good load , 100 W should be ok .............

Some years back I made and  testee , low power , a 2,7 Ghz coupler .

The customer put 400 watts through it , and it melted ...............!

On 14 June 2019 at 17:56 simonchettle <simon@...> wrote:

This is  a simple question what is the maximum power anyone would risk using a 1/4 length strip line on FR4 on 23cms ? 
 
Why because my metal working tools and skills are close zero and I am thinking of building a Wilkinson divider. 
 
I am thinking of combining two power amplifiers each of circa 100 W  O/P. 
 
 
Cheers
 
 
Simon
 
G8ATB
 


 


 

Re: ADF5355 sketch in latest Scatterpoint

brian.flynn
 

Hi Barry,

I just double checked out both the Rotary.h library and RotaryEncoder.h library.  Both compile  and work OK on my setup at least.  I confusingly left the reference to the Encoder.h libray on the  line. I have now removed it.

73s
Brian GM8BJF

RAL parts

SAM JEWELL
 

Folks,
Well, that generated some interest!
I really want to offer these items at RAL. It saves packaging stuff to post (certainly not the 48cm dish and feed!).
What is left over at the end of the day I will be willing to ship (except that dish).
Please, cash only at RAL.  These are my own items and not part of my normal DDKit hobby business. Just having another shack/garage clear out. All items have not been used for the usual 2-5 yearzzzzzz.

I do have a couple of the WA5VJB 2.4GHz circular patch feeds left for sale. I hope to get more from Kent in the next few weeks. I’ll bring these few to RAL. Why go serial when you can go parallel!

73 de Sam

Re: RAL parts

Andy G4JNT
 

I may be interested Sam.



Virus-free. www.avg.com


On Sat, 15 Jun 2019 at 11:34, SAM JEWELL via Groups.Io <jewell=btinternet.com@groups.io> wrote:
Folks,
Well, that generated some interest!
I really want to offer these items at RAL. It saves packaging stuff to post (certainly not the 48cm dish and feed!).
What is left over at the end of the day I will be willing to ship (except that dish).
Please, cash only at RAL.  These are my own items and not part of my normal DDKit hobby business. Just having another shack/garage clear out. All items have not been used for the usual 2-5 yearzzzzzz.

I do have a couple of the WA5VJB 2.4GHz circular patch feeds left for sale. I hope to get more from Kent in the next few weeks. I’ll bring these few to RAL. Why go serial when you can go parallel!

73 de Sam

Re: RAL parts

SAM JEWELL
 

OK Andy,
Some of it is currently under offer, but quite a bit still available.

Sam

On Saturday, June 15, 2019, 2:15 pm, Andy G4JNT <andy.g4jnt@...> wrote:

I may be interested Sam.



Virus-free. www.avg.com

On Sat, 15 Jun 2019 at 11:34, SAM JEWELL via Groups.Io <jewell=btinternet.com@groups.io> wrote:
Folks,
Well, that generated some interest!
I really want to offer these items at RAL. It saves packaging stuff to post (certainly not the 48cm dish and feed!).
What is left over at the end of the day I will be willing to ship (except that dish).
Please, cash only at RAL.  These are my own items and not part of my normal DDKit hobby business. Just having another shack/garage clear out. All items have not been used for the usual 2-5 yearzzzzzz.

I do have a couple of the WA5VJB 2.4GHz circular patch feeds left for sale. I hope to get more from Kent in the next few weeks. I’ll bring these few to RAL. Why go serial when you can go parallel!

73 de Sam

Re: Maximum Power using FR4 board ?

Chris Bartram G4DGU
 

My, perhaps slightly jaundiced, view is that although fully characterised FR4 from a decent manufacturer with 1oz copper is capable of handing a couple of hundred watts in amateur applications at 1.3GHz when used for microstrip circuitry, there are better ways. John, 'XDY, gets part of the way to the solution I'd use.

That is to forget microstrip! It is a useful transmission line medium for applications which are intended for some form of production, and with care and understanding, can be made to work adequately for many low-power applications - even using FR4 - up to 10GHz. However, as a way making a one-off power hybrid, it's a poor use of the available technologies.

If I wanted to make a combiner for a couple of power amplifiers for 23cm, I'd use air stripline. In fact I've done it, and they are sitting on a shelf waiting for me to find time to get around to putting a decent 1.3GHz system on the air. Stripline, where a conductor is suspended between two ground planes, is capable of very much lower losses than any comparable microstrip design.  My 90degree hybrids use a pair of lines parallel to each other along their broad faces, and each each offset from the centre line of the sandwich. The design equations are relatively simple, and unlike microstrip are not approximations. Unfortunately, I don't think any of this has been published recently in the amateur literature. The classic book on the subject is Harlan Howe's 'Stripline Circuit Design'. That should be available in most decent engineering libraries. The maths which Howe uses isn't intimidating, and as the book was written before the age of the PC, there are a lot of design nomographs. I have a copy, but I don't currently have time to write anything further, however I'm sure that there are others here who could produce an article for 'Scatterpoint' summarising the design method.

73 and enjoy MMRT!

Chris

G4DGU

_._,_._

Re: ADF5355 sketch in latest Scatterpoint

Barry Chambers
 

Hi Brian

I noticed that the RotaryEncoder library at the link you gave had both the .h and .cpp files as just Rotary, hence my slight mod - hope you don't mind my posting to the Group rather than just you.

Anyway, a nice piece of software - many thanks for posting it.

73

Barry, G8AGN
On 15/06/2019 11:09, brian.flynn via Groups.Io wrote:

Hi Barry,

I just double checked out both the Rotary.h library and RotaryEncoder.h library.  Both compile  and work OK on my setup at least.  I confusingly left the reference to the Encoder.h libray on the  line. I have now removed it.

73s
Brian GM8BJF

Feeding an LNB with an external reference through the coax

Arved M0KDS
 

Good afternoon all,

I've been working on locking my LNB with a GPSDO reference signal for QO-100 use.
The LNB I'be got is a GI-202 with two separate outputs. My plan is to modify one side to accept a reference signal while the other one will stay stock for DATV use. 
Unfortunately, I can't seem to get the LNB to lock with the reference signal being fed through the coax. I'm using a 100nF capacitor connected to the more sensitive pad (found by testing) and then running a wire from the cap to the f-connector pin. For some reason that isn't working at all. 

If I connect a piece of coax to the sensitive pad and feeding it directly to the LNB without going through the IF coax it works perfectly, no issues whatsoever. 
Does anyone have an idea why feeding through the IF coax isn't working at all?

I did use a probe to see if the reference signal is actually coming through to the LNB - it comes in loud and clear, with a few dBs of loss which comes from the RG-6 coaxial cable. 
Another thing I noticed is that the pads on the modified side have a voltage of about 0.2V on them, whilst the pads on the other unmodified side have about 2V on them. 

If anyone has an idea what might be happening here that would be great. I attached some pictures of my work to this message/email. 

Many thanks and 73,

Arved M0KDS

Re: Feeding an LNB with an external reference through the coax

Keith Le Boutillier
 

Hi Arved

 

Try a 10nf dc blocking cap with a 62 ohm or similar termination resistor

 

73 Keith GU6EFB

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Arved M0KDS
Sent: 16 June 2019 15:07
To: UKMicrowaves@groups.io
Subject: [UKMicrowaves] Feeding an LNB with an external reference through the coax

 

Good afternoon all,

I've been working on locking my LNB with a GPSDO reference signal for QO-100 use.
The LNB I'be got is a GI-202 with two separate outputs. My plan is to modify one side to accept a reference signal while the other one will stay stock for DATV use. 
Unfortunately, I can't seem to get the LNB to lock with the reference signal being fed through the coax. I'm using a 100nF capacitor connected to the more sensitive pad (found by testing) and then running a wire from the cap to the f-connector pin. For some reason that isn't working at all. 

If I connect a piece of coax to the sensitive pad and feeding it directly to the LNB without going through the IF coax it works perfectly, no issues whatsoever. 
Does anyone have an idea why feeding through the IF coax isn't working at all?

I did use a probe to see if the reference signal is actually coming through to the LNB - it comes in loud and clear, with a few dBs of loss which comes from the RG-6 coaxial cable. 
Another thing I noticed is that the pads on the modified side have a voltage of about 0.2V on them, whilst the pads on the other unmodified side have about 2V on them. 

If anyone has an idea what might be happening here that would be great. I attached some pictures of my work to this message/email. 

Many thanks and 73,

Arved M0KDS

Re: Feeding an LNB with an external reference through the coax

Arved M0KDS
 

Hi keith,

thanks for getting back to me. 

Unfortunately I've only got 1nF and 100nF caps here, so that's a bit unfortunate. 

I tried adding a 56Ohm Resistor, it seems to have made it worse when fed directly at the pad with a coaxial cable. 
Feeding the reference through the coax is still not working.

73 Arved M0KDS

Re: Feeding an LNB with an external reference through the coax

militaryoperator
 




Feeding the reference through the coax is still not working.


Have you tested the coax and the connectors each end ?


Ben

Re: Feeding an LNB with an external reference through the coax

Keith Le Boutillier
 

Hi Arved

 

What LNB and frequency are you using 25 or 27Mhz have you googled to see if there is information on how others have moded their LNB?

Do you have a frequency counter are you seeing that frequency at the LNB  

Have you checked the cable and connectors for continuity silly things that can get over looked

 

73 Keith GU6EFB  

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Arved M0KDS
Sent: 16 June 2019 17:16
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Feeding an LNB with an external reference through the coax

 

Hi keith,

thanks for getting back to me. 

Unfortunately I've only got 1nF and 100nF caps here, so that's a bit unfortunate. 

I tried adding a 56Ohm Resistor, it seems to have made it worse when fed directly at the pad with a coaxial cable. 
Feeding the reference through the coax is still not working.

73 Arved M0KDS

Re: Maximum Power using FR4 board ?

Neil Smith G4DBN
 

Hi Simon, if you need some metalbashing doing to make a stripline combiner, I would be happy to help with the fiddly bits. Drop me an email to neil@...

Seems sad to have to compromise your design for the sake of getting a bit of machining done.

Neil G4DBN

Simon wrote:
This is  a simple question what is the maximum power anyone would risk using a 1/4 length strip line on FR4 on 23cms ? 
 
Why because my metal working tools and skills are close zero and I am thinking of building a Wilkinson divider. 

Re: Feeding an LNB with an external reference through the coax

Colin G4EML
 

Are you sure you have completely disconnected the socket you are using for the reference input from its original connections?
If you have left the DC feed inductor connected it will look like a very low impedance to ground when fed with 25MHz which could be reducing the signal level too much.
 
 
 
 
 

From: Arved M0KDS
Sent: Sunday, June 16, 2019 5:16 PM
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Feeding an LNB with an external reference through the coax
 
Hi keith,

thanks for getting back to me.

Unfortunately I've only got 1nF and 100nF caps here, so that's a bit unfortunate.

I tried adding a 56Ohm Resistor, it seems to have made it worse when fed directly at the pad with a coaxial cable.
Feeding the reference through the coax is still not working.

73 Arved M0KDS

Re: Feeding an LNB with an external reference through the coax

Colin G4EML
 

Are you sure you have completely disconnected the socket you are using for the reference input from its original connections?
If you have left the DC feed inductor connected it will look like a very low impedance to ground when fed with 25MHz which could be reducing the signal level too much.
 
 
 
 
 

From: Arved M0KDS
Sent: Sunday, June 16, 2019 5:16 PM
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Feeding an LNB with an external reference through the coax
 
Hi keith,

thanks for getting back to me.

Unfortunately I've only got 1nF and 100nF caps here, so that's a bit unfortunate.

I tried adding a 56Ohm Resistor, it seems to have made it worse when fed directly at the pad with a coaxial cable.
Feeding the reference through the coax is still not working.

73 Arved M0KDS

Re: Maximum Power using FR4 board ?

KENT BRITAIN
 

Are you looking for a 2 way or a 4 way?    I just picked up a dozen commercial 4 way power dividers.  Kent



On Sunday, June 16, 2019, 1:29:31 PM CDT, Neil Smith G4DBN <neil@...> wrote:


Hi Simon, if you need some metalbashing doing to make a stripline combiner, I would be happy to help with the fiddly bits. Drop me an email to neil@...

Seems sad to have to compromise your design for the sake of getting a bit of machining done.

Neil G4DBN

Simon wrote:
This is  a simple question what is the maximum power anyone would risk using a 1/4 length strip line on FR4 on 23cms ? 
 
Why because my metal working tools and skills are close zero and I am thinking of building a Wilkinson divider.