Pulse forming network design - any hints? - UK Vintage Radio Repair and Restoration Discussion Forum

Al (astral highway) · 27th Oct 2007, 10:18 am

Does anybody know of an accessible guide to designing pulse forming networks, or know where I can see a schematic for an old radar modulator using a thyratron?

The older the better, as I want to stay at the lowest possible frequencies, where I have some chance of understanding what's going on!

I know absolutely nada about this, so treat me as a complete radar novice, please.

Many thanks

Astral

M0AFJ, Tim · 29th Oct 2007, 5:46 pm

Maybe worth putting this request on the IET communications forum

http://www.theiet.org/Forums/forum/index.cfm

I'm sure there will be many there who will help

Cheers
Tim M0AFJ

Al (astral highway) · 30th Oct 2007, 11:07 am

Quote:

Originally Posted by M0AFJ

Maybe worth putting this request on the IET communications forum

http://www.theiet.org/Forums/forum/index.cfm

I'm sure there will be many there who will help

Cheers
Tim M0AFJ

Thanks Tim! (MOAFJ)

Malcolm G6ANZ · 30th Oct 2007, 1:30 pm

How much information do you need? I can let you have a copy of part of a manual describing line modulators and PFN's as used by Varian. The manual is part of the set used for the maintenance of linacs, basically a high power PFN for a 5MW pk power magnetron.
Let me know if it would be any use.

Malcolm

jim_beacon · 31st Oct 2007, 12:29 am

Somewhere (!) I have the joint services textbook which covers this. I'll try and dig it out, but it is basically a transmission line tuned to the PRF.

Jim.

RobinBirch · 2nd Nov 2007, 11:32 am

Chapter 5 Microwaves and Radar Electronics Pollard & Sturtevant 1948 John Wiley & Sons

Your library should be able to get a copy.

Robin

Al (astral highway) · 2nd Nov 2007, 11:59 am

Quote:

Originally Posted by g6anz

How much information do you need? I can let you have a copy of part of a manual describing line modulators and PFN's as used by Varian. The manual is part of the set used for the maintenance of linacs, basically a high power PFN for a 5MW pk power magnetron.
Let me know if it would be any use.

Malcolm

5MW! crikey. I am only interested in a sub-kilowatt output, but I imagine the PFN side will be very similar in principle, if not in the detail.

Al (astral highway) · 2nd Nov 2007, 12:00 pm

Quote:

Originally Posted by jim_beacon

Somewhere (!) I have the joint services textbook which covers this. I'll try and dig it out, but it is basically a transmission line tuned to the PRF.

Jim.

Thanks Jim. If you were in a position to photocopy the relevant section, I'd pay you for the trouble.

Al (astral highway) · 2nd Nov 2007, 12:01 pm

Quote:

Originally Posted by RobinBirch

Chapter 5 Microwaves and Radar Electronics Pollard & Sturtevant 1948 John Wiley & Sons

Your library should be able to get a copy.

Robin

Thanks Robin, that's a great help.

M0AFJ, Tim · 3rd Nov 2007, 4:12 pm

Astral, please slate my curiosity,are you going to build a radar transmitter?
Just interested

Al (astral highway) · 3rd Nov 2007, 4:24 pm

I have been thinking about it, yes. Even a very small one will do. But I'd certainly like to get to the position of being able to build one, even if I don't actually go that far.

Hence: https://www.vintage-radio.net/forum/...ad.php?t=22075

Malcolm G6ANZ · 5th Nov 2007, 2:32 pm

Ah yes, may be a bit over the top in terms of power. However the general theory is the same for all PFN's, Charge up a bank of capacitors from a high voltage source and then discharge them through a coil to make a pulse as opposed to a spike which you would get if the caps were just discharged in to a load. The usual device for the discharge is a thyratron as it can switch a high voltage and current very quickly. A thyristor could be used but they tend to destroy themselves, being of the solid type

Malcolm

27th Oct 2007, 10:18 am	#1
Al (astral highway) Dekatron Join Date: Nov 2006 Location: London, UK. Posts: 3,496	Pulse forming network design - any hints? Does anybody know of an accessible guide to designing pulse forming networks, or know where I can see a schematic for an old radar modulator using a thyratron? The older the better, as I want to stay at the lowest possible frequencies, where I have some chance of understanding what's going on! I know absolutely nada about this, so treat me as a complete radar novice, please. Many thanks Astral

29th Oct 2007, 5:46 pm	#2
M0AFJ, Tim Hexode Join Date: Mar 2006 Location: Helston, Cornwall, UK. Posts: 303	Re: Pulse forming network design - any hints? Maybe worth putting this request on the IET communications forum http://www.theiet.org/Forums/forum/index.cfm I'm sure there will be many there who will help Cheers Tim M0AFJ

30th Oct 2007, 1:30 pm	#4
Malcolm G6ANZ Octode Join Date: Feb 2006 Location: Bristol, UK. Posts: 1,041	Re: Pulse forming network design - any hints? How much information do you need? I can let you have a copy of part of a manual describing line modulators and PFN's as used by Varian. The manual is part of the set used for the maintenance of linacs, basically a high power PFN for a 5MW pk power magnetron. Let me know if it would be any use. Malcolm

31st Oct 2007, 12:29 am	#5
jim_beacon Retired Dormant Member Join Date: Mar 2003 Location: Bishop's Waltham, Hants, UK. Posts: 939	Re: Pulse forming network design - any hints? Somewhere (!) I have the joint services textbook which covers this. I'll try and dig it out, but it is basically a transmission line tuned to the PRF. Jim.

2nd Nov 2007, 11:32 am	#6
RobinBirch Hexode Join Date: Apr 2003 Location: Cotswolds, UK. Posts: 465	Re: Pulse forming network design - any hints? Chapter 5 Microwaves and Radar Electronics Pollard & Sturtevant 1948 John Wiley & Sons Your library should be able to get a copy. Robin

3rd Nov 2007, 4:12 pm	#10
M0AFJ, Tim Hexode Join Date: Mar 2006 Location: Helston, Cornwall, UK. Posts: 303	Re: Pulse forming network design - any hints? Astral, please slate my curiosity,are you going to build a radar transmitter? Just interested

3rd Nov 2007, 4:24 pm	#11
Al (astral highway) Dekatron Join Date: Nov 2006 Location: London, UK. Posts: 3,496	Re: Pulse forming network design - any hints? I have been thinking about it, yes. Even a very small one will do. But I'd certainly like to get to the position of being able to build one, even if I don't actually go that far. Hence: https://www.vintage-radio.net/forum/...ad.php?t=22075

5th Nov 2007, 2:32 pm	#12
Malcolm G6ANZ Octode Join Date: Feb 2006 Location: Bristol, UK. Posts: 1,041	Re: Pulse forming network design - any hints? Ah yes, may be a bit over the top in terms of power. However the general theory is the same for all PFN's, Charge up a bank of capacitors from a high voltage source and then discharge them through a coil to make a pulse as opposed to a spike which you would get if the caps were just discharged in to a load. The usual device for the discharge is a thyratron as it can switch a high voltage and current very quickly. A thyristor could be used but they tend to destroy themselves, being of the solid type Malcolm