Topics

Semiconductor switch.


Colin Ranson
 

 

All,

 

I just paid a UK supplier £5.99  Chinese made unfortunately, but needs must)  for the following pack of two:

 

 

Kuhne want 27euro + the usual post etc for just one similar albeit with a sequencer, but don’t most people run a dedicated sequencer with their rig/transverter/VNLA etc ? ie like me ?

 

The amp I have for 3.4GHz needs hard DC switching, can’t see any other way with Mosfets.

 

Keep those irons hot folks,

 

Colin de G8LBS.

 

Sent from Mail for Windows 10

 


Andy G4JNT
 

This may be a silly question but...
Those modules just appear to be a couple of MOSFETs in parallel and a few Rs,   Why do you not just buy some suitable devices and roll your own?

P-Channel switches at a guess, pull to ground to activate?
There are plenty of high current P-Channel devices around, so just take your pick from the RS or Farnells (*) of this World.

(*)   Other UK component suppliers are available.



On Wed, 27 Jan 2021 at 19:05, Colin Ranson <g8lbs@...> wrote:

 

All,

 

I just paid a UK supplier £5.99  Chinese made unfortunately, but needs must)  for the following pack of two:

 

 

Kuhne want 27euro + the usual post etc for just one similar albeit with a sequencer, but don’t most people run a dedicated sequencer with their rig/transverter/VNLA etc ? ie like me ?

 

The amp I have for 3.4GHz needs hard DC switching, can’t see any other way with Mosfets.

 

Keep those irons hot folks,

 

Colin de G8LBS.

 

Sent from Mail for Windows 10

 


Andy G4JNT
 

Actually, if the green spot on the LED is the negative side, that picture is of a pair of N-Channel devices switched to ground with a positive drive voltage.   In which case there are even more suitable ones to choose from.



On Wed, 27 Jan 2021 at 19:27, Andy Talbot <andy.g4jnt@...> wrote:
This may be a silly question but...
Those modules just appear to be a couple of MOSFETs in parallel and a few Rs,   Why do you not just buy some suitable devices and roll your own?

P-Channel switches at a guess, pull to ground to activate?
There are plenty of high current P-Channel devices around, so just take your pick from the RS or Farnells (*) of this World.

(*)   Other UK component suppliers are available.



On Wed, 27 Jan 2021 at 19:05, Colin Ranson <g8lbs@...> wrote:

 

All,

 

I just paid a UK supplier £5.99  Chinese made unfortunately, but needs must)  for the following pack of two:

 

 

Kuhne want 27euro + the usual post etc for just one similar albeit with a sequencer, but don’t most people run a dedicated sequencer with their rig/transverter/VNLA etc ? ie like me ?

 

The amp I have for 3.4GHz needs hard DC switching, can’t see any other way with Mosfets.

 

Keep those irons hot folks,

 

Colin de G8LBS.

 

Sent from Mail for Windows 10

 


militaryoperator
 


Only £5.08 from another UK supplier Colin!!
313390770002
Ben



All,
 
I just paid a UK supplier £5.99  Chinese made unfortunately, but needs must)  for the following pack of two:
( 133549042395 )
Pack of: Pack of 2
Kuhne want 27euro + the usual post etc for just one similar albeit with a sequencer, but don’t most people run a dedicated sequencer with their rig/transverter/VNLA etc ? ie like me ?
The amp I have for 3.4GHz needs hard DC switching, can’t see any other way with Mosfets.
Keep those irons hot folks,
Colin de G8LBS.


Colin Ranson
 

I did think about it Andy but by the time I’ve sourced them, done this done that etc just hardly worth the effort.   Now on the other hand I have recently designed a PCB (etched it today)  with at least 50 SMD components on it.... so I do keep the old grey matter firing off.

 

How long this post 70 year old brain will allow it I don’t know.

 

73’s

 

 

Colin.

 

Sent from Mail for Windows 10

 

From: Andy G4JNT
Sent: 27 January 2021 19:27
To: UK Microwaves groups.io
Subject: Re: [UKMicrowaves] Semiconductor switch.

 

This may be a silly question but...

Those modules just appear to be a couple of MOSFETs in parallel and a few Rs,   Why do you not just buy some suitable devices and roll your own?

 

P-Channel switches at a guess, pull to ground to activate?

There are plenty of high current P-Channel devices around, so just take your pick from the RS or Farnells (*) of this World.

 

(*)   Other UK component suppliers are available.

 

Andy

 

 

 

On Wed, 27 Jan 2021 at 19:05, Colin Ranson <g8lbs@...> wrote:

 

All,

 

I just paid a UK supplier £5.99  Chinese made unfortunately, but needs must)  for the following pack of two:

 

 

Kuhne want 27euro + the usual post etc for just one similar albeit with a sequencer, but don’t most people run a dedicated sequencer with their rig/transverter/VNLA etc ? ie like me ?

 

The amp I have for 3.4GHz needs hard DC switching, can’t see any other way with Mosfets.

 

Keep those irons hot folks,

 

Colin de G8LBS.

 

Sent from Mail for Windows 10

 

 


Robin Szemeti - G1YFG
 

I can't see a use for them as they are N type mosfets,  low side switches,  so go between the load and ground ... most of the stuff I would use one for would be P type mosfets between +Vcc and the amplifier.

On Wed, 27 Jan 2021 at 20:14, Colin Ranson <g8lbs@...> wrote:

I did think about it Andy but by the time I’ve sourced them, done this done that etc just hardly worth the effort.   Now on the other hand I have recently designed a PCB (etched it today)  with at least 50 SMD components on it.... so I do keep the old grey matter firing off.

 

How long this post 70 year old brain will allow it I don’t know.

 

73’s

 

 

Colin.

 

Sent from Mail for Windows 10

 

From: Andy G4JNT
Sent: 27 January 2021 19:27
To: UK Microwaves groups.io
Subject: Re: [UKMicrowaves] Semiconductor switch.

 

This may be a silly question but...

Those modules just appear to be a couple of MOSFETs in parallel and a few Rs,   Why do you not just buy some suitable devices and roll your own?

 

P-Channel switches at a guess, pull to ground to activate?

There are plenty of high current P-Channel devices around, so just take your pick from the RS or Farnells (*) of this World.

 

(*)   Other UK component suppliers are available.

 

Andy

 

 

 

On Wed, 27 Jan 2021 at 19:05, Colin Ranson <g8lbs@...> wrote:

 

All,

 

I just paid a UK supplier £5.99  Chinese made unfortunately, but needs must)  for the following pack of two:

 

 

Kuhne want 27euro + the usual post etc for just one similar albeit with a sequencer, but don’t most people run a dedicated sequencer with their rig/transverter/VNLA etc ? ie like me ?

 

The amp I have for 3.4GHz needs hard DC switching, can’t see any other way with Mosfets.

 

Keep those irons hot folks,

 

Colin de G8LBS.

 

Sent from Mail for Windows 10

 

 


--
Robin Szemeti - G1YFG


Colin Ranson
 

Hi Robin,

 

I can select ground on TX or + 5v on TX from the sequencer to the amplifier, I do the + volts on TX with my 2320MHz amplifier – still languishing in the loft with no external antenna as yet.   Works for me.

 

Regards,

 

And welcome back on the other platform.

 

Colin.

 

Sent from Mail for Windows 10

 

From: Robin Szemeti - G1YFG
Sent: 27 January 2021 20:33
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Semiconductor switch.

 

I can't see a use for them as they are N type mosfets,  low side switches,  so go between the load and ground ... most of the stuff I would use one for would be P type mosfets between +Vcc and the amplifier.

 

On Wed, 27 Jan 2021 at 20:14, Colin Ranson <g8lbs@...> wrote:

I did think about it Andy but by the time I’ve sourced them, done this done that etc just hardly worth the effort.   Now on the other hand I have recently designed a PCB (etched it today)  with at least 50 SMD components on it.... so I do keep the old grey matter firing off.

 

How long this post 70 year old brain will allow it I don’t know.

 

73’s

 

 

Colin.

 

Sent from Mail for Windows 10

 

From: Andy G4JNT
Sent: 27 January 2021 19:27
To: UK Microwaves groups.io
Subject: Re: [UKMicrowaves] Semiconductor switch.

 

This may be a silly question but...

Those modules just appear to be a couple of MOSFETs in parallel and a few Rs,   Why do you not just buy some suitable devices and roll your own?

 

P-Channel switches at a guess, pull to ground to activate?

There are plenty of high current P-Channel devices around, so just take your pick from the RS or Farnells (*) of this World.

 

(*)   Other UK component suppliers are available.

 

Andy

 

 

 

On Wed, 27 Jan 2021 at 19:05, Colin Ranson <g8lbs@...> wrote:

 

All,

 

I just paid a UK supplier £5.99  Chinese made unfortunately, but needs must)  for the following pack of two:

 

 

Kuhne want 27euro + the usual post etc for just one similar albeit with a sequencer, but don’t most people run a dedicated sequencer with their rig/transverter/VNLA etc ? ie like me ?

 

The amp I have for 3.4GHz needs hard DC switching, can’t see any other way with Mosfets.

 

Keep those irons hot folks,

 

Colin de G8LBS.

 

Sent from Mail for Windows 10

 

 


--
Robin Szemeti - G1YFG

 


Robin Szemeti - G1YFG
 

But to power/depower the amplifier with them (which is what I assume you would be using them for?) you would have to isolate the -Ve of the amplifier which could be quite hard with all the RF cables having a ground, then use this device to ground the amplifier on transmit. 

Most people use a P type and switch the +Ve  .. being able to switch the -Ve with one of these devices is troublesome if the device picks up a -Ve via the RF cable ... or are you using it for something else?



On Wed, 27 Jan 2021 at 20:54, Colin Ranson <g8lbs@...> wrote:

Hi Robin,

 

I can select ground on TX or + 5v on TX from the sequencer to the amplifier, I do the + volts on TX with my 2320MHz amplifier – still languishing in the loft with no external antenna as yet.   Works for me.

 

Regards,

 

And welcome back on the other platform.

 

Colin.

 

Sent from Mail for Windows 10

 

From: Robin Szemeti - G1YFG
Sent: 27 January 2021 20:33
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Semiconductor switch.

 

I can't see a use for them as they are N type mosfets,  low side switches,  so go between the load and ground ... most of the stuff I would use one for would be P type mosfets between +Vcc and the amplifier.

 

On Wed, 27 Jan 2021 at 20:14, Colin Ranson <g8lbs@...> wrote:

I did think about it Andy but by the time I’ve sourced them, done this done that etc just hardly worth the effort.   Now on the other hand I have recently designed a PCB (etched it today)  with at least 50 SMD components on it.... so I do keep the old grey matter firing off.

 

How long this post 70 year old brain will allow it I don’t know.

 

73’s

 

 

Colin.

 

Sent from Mail for Windows 10

 

From: Andy G4JNT
Sent: 27 January 2021 19:27
To: UK Microwaves groups.io
Subject: Re: [UKMicrowaves] Semiconductor switch.

 

This may be a silly question but...

Those modules just appear to be a couple of MOSFETs in parallel and a few Rs,   Why do you not just buy some suitable devices and roll your own?

 

P-Channel switches at a guess, pull to ground to activate?

There are plenty of high current P-Channel devices around, so just take your pick from the RS or Farnells (*) of this World.

 

(*)   Other UK component suppliers are available.

 

Andy

 

 

 

On Wed, 27 Jan 2021 at 19:05, Colin Ranson <g8lbs@...> wrote:

 

All,

 

I just paid a UK supplier £5.99  Chinese made unfortunately, but needs must)  for the following pack of two:

 

 

Kuhne want 27euro + the usual post etc for just one similar albeit with a sequencer, but don’t most people run a dedicated sequencer with their rig/transverter/VNLA etc ? ie like me ?

 

The amp I have for 3.4GHz needs hard DC switching, can’t see any other way with Mosfets.

 

Keep those irons hot folks,

 

Colin de G8LBS.

 

Sent from Mail for Windows 10

 

 


--
Robin Szemeti - G1YFG

 


--
Robin Szemeti - G1YFG


Tom GM8MJV
 

W6PQL does something similar - have used them to switch PA and works well.



Tom

On 27 Jan 2021, at 19:05, Colin Ranson <g8lbs@...> wrote:

 
All,
 
I just paid a UK supplier £5.99  Chinese made unfortunately, but needs must)  for the following pack of two:
 
 
Kuhne want 27euro + the usual post etc for just one similar albeit with a sequencer, but don’t most people run a dedicated sequencer with their rig/transverter/VNLA etc ? ie like me ?
 
The amp I have for 3.4GHz needs hard DC switching, can’t see any other way with Mosfets.
 
Keep those irons hot folks,
 
Colin de G8LBS.
 
Sent from Mail for Windows 10
 


Andy G4JNT
 

Seems a complex bit of circuitry - but it looks like he's done it that way to reduce the O/C voltage on the PTT control line with the non-inverting common base device.
If you use the GND-To-Tx standard as inputm and it can withstand 50V, simply pulling the gate of the P-channel FET to ground will suffice.   Using  pot-divider to avoid exceeding Vgmax
 


On Wed, 27 Jan 2021 at 21:32, Tom GM8MJV <tom@...> wrote:
W6PQL does something similar - have used them to switch PA and works well.



Tom

On 27 Jan 2021, at 19:05, Colin Ranson <g8lbs@...> wrote:

 
All,
 
I just paid a UK supplier £5.99  Chinese made unfortunately, but needs must)  for the following pack of two:
 
 
Kuhne want 27euro + the usual post etc for just one similar albeit with a sequencer, but don’t most people run a dedicated sequencer with their rig/transverter/VNLA etc ? ie like me ?
 
The amp I have for 3.4GHz needs hard DC switching, can’t see any other way with Mosfets.
 
Keep those irons hot folks,
 
Colin de G8LBS.
 
Sent from Mail for Windows 10
 


Conrad, PA5Y
 

I have a good number of these in use. I switch 28V masthead relays and 12, 28 and 50V supplies for amplifiers. The only reason I mention it is because they are very reliable. Rolling your own is also easy if you have time. I don’t and so I buy these from W6PQL.

 

73

 

Conrad

 

From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> On Behalf Of Tom GM8MJV via groups.io
Sent: 27 January 2021 22:32
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Semiconductor switch.

 

W6PQL does something similar - have used them to switch PA and works well.

 

 

 

Tom

 

On 27 Jan 2021, at 19:05, Colin Ranson <g8lbs@...> wrote:

 

 

All,

 

I just paid a UK supplier £5.99  Chinese made unfortunately, but needs must)  for the following pack of two:

 

 

Kuhne want 27euro + the usual post etc for just one similar albeit with a sequencer, but don’t most people run a dedicated sequencer with their rig/transverter/VNLA etc ? ie like me ?

 

The amp I have for 3.4GHz needs hard DC switching, can’t see any other way with Mosfets.

 

Keep those irons hot folks,

 

Colin de G8LBS.

 

Sent from Mail for Windows 10

 

 


Robin Szemeti - G1YFG
 

Sticking a zener on the gate is another tried and tested way of making sure you don't exceed Vgs max.   I use this technique on all our big mosfet audio amps for a good number of years now. You'd be surprised how much mess a lateral mosfet makes if the gate is overdriven when it's on the end of an SMPS capable of 10kw+

On Wed, 27 Jan 2021 at 21:40, Andy G4JNT <andy.g4jnt@...> wrote:
Seems a complex bit of circuitry - but it looks like he's done it that way to reduce the O/C voltage on the PTT control line with the non-inverting common base device.
If you use the GND-To-Tx standard as inputm and it can withstand 50V, simply pulling the gate of the P-channel FET to ground will suffice.   Using  pot-divider to avoid exceeding Vgmax
 


On Wed, 27 Jan 2021 at 21:32, Tom GM8MJV <tom@...> wrote:
W6PQL does something similar - have used them to switch PA and works well.



Tom

On 27 Jan 2021, at 19:05, Colin Ranson <g8lbs@...> wrote:

 
All,
 
I just paid a UK supplier £5.99  Chinese made unfortunately, but needs must)  for the following pack of two:
 
 
Kuhne want 27euro + the usual post etc for just one similar albeit with a sequencer, but don’t most people run a dedicated sequencer with their rig/transverter/VNLA etc ? ie like me ?
 
The amp I have for 3.4GHz needs hard DC switching, can’t see any other way with Mosfets.
 
Keep those irons hot folks,
 
Colin de G8LBS.
 
Sent from Mail for Windows 10
 


--
Robin Szemeti - G1YFG


Andy G4JNT
 

During the development of a 400W class-E amp for 475kHz, powered from a 50V 20A supply, I had an IRF 450 go in style.  A jet of flame shot out of the side, just like a small blowlamp.  Different failure cause - probably.  But the same result.   I've also had TO220 FETs blow apart, throwing bits of epoxy across the room.

Who said semiconductors were safer than valve technology.



On Wed, 27 Jan 2021 at 21:49, Robin Szemeti - G1YFG <robin@...> wrote:
Sticking a zener on the gate is another tried and tested way of making sure you don't exceed Vgs max.   I use this technique on all our big mosfet audio amps for a good number of years now. You'd be surprised how much mess a lateral mosfet makes if the gate is overdriven when it's on the end of an SMPS capable of 10kw+

On Wed, 27 Jan 2021 at 21:40, Andy G4JNT <andy.g4jnt@...> wrote:
Seems a complex bit of circuitry - but it looks like he's done it that way to reduce the O/C voltage on the PTT control line with the non-inverting common base device.
If you use the GND-To-Tx standard as inputm and it can withstand 50V, simply pulling the gate of the P-channel FET to ground will suffice.   Using  pot-divider to avoid exceeding Vgmax
 


On Wed, 27 Jan 2021 at 21:32, Tom GM8MJV <tom@...> wrote:
W6PQL does something similar - have used them to switch PA and works well.



Tom

On 27 Jan 2021, at 19:05, Colin Ranson <g8lbs@...> wrote:

 
All,
 
I just paid a UK supplier £5.99  Chinese made unfortunately, but needs must)  for the following pack of two:
 
 
Kuhne want 27euro + the usual post etc for just one similar albeit with a sequencer, but don’t most people run a dedicated sequencer with their rig/transverter/VNLA etc ? ie like me ?
 
The amp I have for 3.4GHz needs hard DC switching, can’t see any other way with Mosfets.
 
Keep those irons hot folks,
 
Colin de G8LBS.
 
Sent from Mail for Windows 10
 


--
Robin Szemeti - G1YFG


Colin Ranson
 

Thanks for all the advice and alternatives, I’ll let you know how I get on with the switches, I could just as well considered using a big Schrack relay to switch the  Vcc.

 

Colin de G8LBS.

 

 

Sent from Mail for Windows 10

 

From: Robin Szemeti - G1YFG
Sent: 27 January 2021 21:30
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Semiconductor switch.

 

But to power/depower the amplifier with them (which is what I assume you would be using them for?) you would have to isolate the -Ve of the amplifier which could be quite hard with all the RF cables having a ground, then use this device to ground the amplifier on transmit. 

 

Most people use a P type and switch the +Ve  .. being able to switch the -Ve with one of these devices is troublesome if the device picks up a -Ve via the RF cable ... or are you using it for something else?

 

 

 

On Wed, 27 Jan 2021 at 20:54, Colin Ranson <g8lbs@...> wrote:

Hi Robin,

 

I can select ground on TX or + 5v on TX from the sequencer to the amplifier, I do the + volts on TX with my 2320MHz amplifier – still languishing in the loft with no external antenna as yet.   Works for me.

 

Regards,

 

And welcome back on the other platform.

 

Colin.

 

Sent from Mail for Windows 10

 

From: Robin Szemeti - G1YFG
Sent: 27 January 2021 20:33
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Semiconductor switch.

 

I can't see a use for them as they are N type mosfets,  low side switches,  so go between the load and ground ... most of the stuff I would use one for would be P type mosfets between +Vcc and the amplifier.

 

On Wed, 27 Jan 2021 at 20:14, Colin Ranson <g8lbs@...> wrote:

I did think about it Andy but by the time I’ve sourced them, done this done that etc just hardly worth the effort.   Now on the other hand I have recently designed a PCB (etched it today)  with at least 50 SMD components on it.... so I do keep the old grey matter firing off.

 

How long this post 70 year old brain will allow it I don’t know.

 

73’s

 

 

Colin.

 

Sent from Mail for Windows 10

 

From: Andy G4JNT
Sent: 27 January 2021 19:27
To: UK Microwaves groups.io
Subject: Re: [UKMicrowaves] Semiconductor switch.

 

This may be a silly question but...

Those modules just appear to be a couple of MOSFETs in parallel and a few Rs,   Why do you not just buy some suitable devices and roll your own?

 

P-Channel switches at a guess, pull to ground to activate?

There are plenty of high current P-Channel devices around, so just take your pick from the RS or Farnells (*) of this World.

 

(*)   Other UK component suppliers are available.

 

Andy

 

 

 

On Wed, 27 Jan 2021 at 19:05, Colin Ranson <g8lbs@...> wrote:

 

All,

 

I just paid a UK supplier £5.99  Chinese made unfortunately, but needs must)  for the following pack of two:

 

 

Kuhne want 27euro + the usual post etc for just one similar albeit with a sequencer, but don’t most people run a dedicated sequencer with their rig/transverter/VNLA etc ? ie like me ?

 

The amp I have for 3.4GHz needs hard DC switching, can’t see any other way with Mosfets.

 

Keep those irons hot folks,

 

Colin de G8LBS.

 

Sent from Mail for Windows 10

 

 


--
Robin Szemeti - G1YFG

 


--
Robin Szemeti - G1YFG

 


Ian White
 

Aluminium-clad wirewound resistors are much more exciting - and also much more convenient since the propellant and projectile come ready-packaged inside the gun barrel. I had one that just happened to be aimed at a PC board when it blew out its guts: an electrolytic cap was wiped clean off the board and the projectile continued in a straight line to embed itself into the side of a relay.

On topic: for switching anything valuable it surely makes sense to use a dedicated High Side Switch IC like the BTS50085 that has built-in protection against a wide range of faults (most of which we probably wouldn't have thought of) and also has a current sense output and control input that are referenced to ground.

73 from Ian GM3SEK


On 27/01/2021 21:58, Andy G4JNT wrote:

During the development of a 400W class-E amp for 475kHz, powered from a 50V 20A supply, I had an IRF 450 go in style.  A jet of flame shot out of the side, just like a small blowlamp.  Different failure cause - probably.  But the same result.   I've also had TO220 FETs blow apart, throwing bits of epoxy across the room.

Who said semiconductors were safer than valve technology.



On Wed, 27 Jan 2021 at 21:49, Robin Szemeti - G1YFG <robin@...> wrote:
Sticking a zener on the gate is another tried and tested way of making sure you don't exceed Vgs max.   I use this technique on all our big mosfet audio amps for a good number of years now. You'd be surprised how much mess a lateral mosfet makes if the gate is overdriven when it's on the end of an SMPS capable of 10kw+

On Wed, 27 Jan 2021 at 21:40, Andy G4JNT <andy.g4jnt@...> wrote:
Seems a complex bit of circuitry - but it looks like he's done it that way to reduce the O/C voltage on the PTT control line with the non-inverting common base device.
If you use the GND-To-Tx standard as inputm and it can withstand 50V, simply pulling the gate of the P-channel FET to ground will suffice.   Using  pot-divider to avoid exceeding Vgmax
 


On Wed, 27 Jan 2021 at 21:32, Tom GM8MJV <tom@...> wrote:
W6PQL does something similar - have used them to switch PA and works well.



Tom

On 27 Jan 2021, at 19:05, Colin Ranson <g8lbs@...> wrote:

 
All,
 
I just paid a UK supplier £5.99  Chinese made unfortunately, but needs must)  for the following pack of two:
 
 
Kuhne want 27euro + the usual post etc for just one similar albeit with a sequencer, but don’t most people run a dedicated sequencer with their rig/transverter/VNLA etc ? ie like me ?
 
The amp I have for 3.4GHz needs hard DC switching, can’t see any other way with Mosfets.
 
Keep those irons hot folks,
 
Colin de G8LBS.
 
Sent from Mail for Windows 10
 


--
Robin Szemeti - G1YFG


David Robinson
 

Thats the design i have been using for the last 10+ years in all 3 variants (12,28 and 48v)
dave
g4fre

. >Tom GM8MJV
Jan 27   

>W6PQL does something similar - have used them to switch PA and works well.
 


John Lemay
 

Seems to me it’s a pity we have to go to sources in the US, Germany or China for these relatively simple building blocks. I’m sure that if Dave G4HUP was still with us it’s the sort of project he would have produced a kit for.

 

This is particularly on my mind at present because I ordered a replacement sequencer from DB6NT on January 1st and it is still in transit (maybe in more ways than one!).

 

Any mini-entrepreneurs out there ?

 

John G4ZTR

 

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of David Robinson
Sent: 28 January 2021 07:51
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Semiconductor switch.

 

Thats the design i have been using for the last 10+ years in all 3 variants (12,28 and 48v)
dave
g4fre

. >Tom GM8MJV

Jan 27   

 

>W6PQL does something similar - have used them to switch PA and works well.

 


Virus-free. www.avg.com


Andy G4JNT
 

What has happened  to building things on Veroboard, bead bug etc?   Over recent years so many people have straightaway gone for the nice shiny cheap PCBs ready made that real home brew, and thinking about what you want to do, investigating what components to work with and putting them together seems to have gone out the window.

There are complaints about the technical content of the magazines - well, if no one makes or designs anything themselves, just assembles modules, what do you expect?

Having said a few emails ago that W8PQL's Switching module seemed a bit over-complicated, I've been forensically examining it, right down to individual resistor component value level at each voltage, even putting together a spreadsheet to test all eventualities.    It's rather neat.   Using resistor values specified in the table at the voltages listed, the PTT input sits at around 3V - so is perfectly amenable to TTL level drive.   The switching threshold is set by the potential divider on the base of the NPN.  The other potential divider on the left of the circuit - that looks a bit superfluous at first sight and  whose output goes to the emitter of the NPN,  forces the emitter to be a couple of hundred mV above the base, ensuring  it is very firmly off when PTT input is high.

As for the entrepreneurs out there - wish I was a decade younger and hadn't already experienced the effort that goes into putting even basic part-kits onto the market.  Design and testing something, getting PCBs manufactured in bulk is a doddle and teh fun bit. 
But ...
Soldering chips to boards and blowing in the code (*), then continuously monitoring your email inbox for orders and Paypal alerts, Getting the right money in, sorting out buying padded bags and large-letter stamps, putting components into bags, downloading and printing postage forms, filling out customs declarations for overseas orders.   That's the soul-destroying tedious bits.     I suppose if you want to make a living out of it, and have a secretary / assistant to do the dridgery  [ I've heard siblings fulfil this role in certain cases :-) ] it's not so bad.

Congratulations to Mike 'LYP for all the effort he must expend on the Chipbank.




On Thu, 28 Jan 2021 at 08:38, John Lemay <john@...> wrote:

Seems to me it’s a pity we have to go to sources in the US, Germany or China for these relatively simple building blocks. I’m sure that if Dave G4HUP was still with us it’s the sort of project he would have produced a kit for.

 

This is particularly on my mind at present because I ordered a replacement sequencer from DB6NT on January 1st and it is still in transit (maybe in more ways than one!).

 

Any mini-entrepreneurs out there ?

 

John G4ZTR

 

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of David Robinson
Sent: 28 January 2021 07:51
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Semiconductor switch.

 

Thats the design i have been using for the last 10+ years in all 3 variants (12,28 and 48v)
dave
g4fre

. >Tom GM8MJV

Jan 27   #60841  

 

>W6PQL does something similar - have used them to switch PA and works well.

 


Virus-free. www.avg.com


Robin Szemeti - G1YFG
 

Hi John,

If there is a demand, I am more than happy to put a PCB into the next order.  They are hardly very difficult,  The " BTS50085" smart switch looks a sensible way to go,  up to 40A at 48V should fulfill most needs of a high side switch. 

I have plans to offer some other boards once they are tested ...


On Thu, 28 Jan 2021 at 08:38, John Lemay <john@...> wrote:

Seems to me it’s a pity we have to go to sources in the US, Germany or China for these relatively simple building blocks. I’m sure that if Dave G4HUP was still with us it’s the sort of project he would have produced a kit for.

 

This is particularly on my mind at present because I ordered a replacement sequencer from DB6NT on January 1st and it is still in transit (maybe in more ways than one!).

 

Any mini-entrepreneurs out there ?

 

John G4ZTR

 

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of David Robinson
Sent: 28 January 2021 07:51
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Semiconductor switch.

 

Thats the design i have been using for the last 10+ years in all 3 variants (12,28 and 48v)
dave
g4fre

. >Tom GM8MJV

Jan 27   #60841  

 

>W6PQL does something similar - have used them to switch PA and works well.

 


Virus-free. www.avg.com


--
Robin Szemeti - G1YFG


Ian White
 

G4HUP did produce a design based on the BTS50085 smart switch (SMD version) but I don't believe it reached full distribution as a kit.

Earlier, VK4DD had produced a fully integrated control board using the TO-220 version of the same IC, mounted vertically to allow a direct terminal connection to the tab.

Sadly, both designers are now SK and both products are now unsupported... but there's nothing much to the circuit itself, just the IC and a pull-down MOSFET to switch it on.

73 from Ian GM3SEK


On 28/01/2021 08:38, John Lemay wrote:

Seems to me it’s a pity we have to go to sources in the US, Germany or China for these relatively simple building blocks. I’m sure that if Dave G4HUP was still with us it’s the sort of project he would have produced a kit for.

 

This is particularly on my mind at present because I ordered a replacement sequencer from DB6NT on January 1st and it is still in transit (maybe in more ways than one!).

 

Any mini-entrepreneurs out there ?

 

John G4ZTR

 

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of David Robinson
Sent: 28 January 2021 07:51
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Semiconductor switch.

 

Thats the design i have been using for the last 10+ years in all 3 variants (12,28 and 48v)
dave
g4fre

. >Tom GM8MJV

Jan 27   

 

>W6PQL does something similar - have used them to switch PA and works well.

 


Virus-free. www.avg.com