By-product of swarf generation


Dave G6HEF
 
Edited

There seems to be some interest regarding machining stuff for microwaves.

I have been considering a directional coupler for a while. So, I recently pressed may machine shop into action to make one for my in-progress 23cm amp.

I'm fairly pleased with the results. With a bit of fiddling it seems fairly easy to get between -30 and -40db coupling just by carful adjusting of the sense lines. A few hundred milliwatts out at legal limit and 3 volts or so from a diode detector. Obviously closer coupling would give higher coupling figures. Through losses really low and return loss approaching 20db. I'll take that for an on-the-fly, making it up as I went along design.

Should do to feed a LED bargraph whatsit.

If I costed my time it'd be worth about £500!

More information including images can be found at my post on Directional Coupler


Andy G4JNT
 

Which is the sort of price one would be, new (ish)



On Mon, 21 Jun 2021 at 21:23, Dave G6HEF <hardknottdave@...> wrote:
If I costed my time it'd be worth about £500!


John Lemay
 

David

 

Good to see someone else making swarf. I wish there was a market for it ………

 

You’ve measured the through loss and the forward coupling. What about directivity ? When you’ve measured that you will know whether it will be useful to measure the SWR or RL of an aerial.

 

Can’t tell from the photos – have you terminated the two pickup lines with a low value resistor ? 50 ohms is typical.

 

Regards

 

John G4ZTR

 

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Dave G6HEF
Sent: 21 June 2021 21:23
To: UKMicrowaves@groups.io
Subject: [UKMicrowaves] By-product of swarf generation

 

[Edited Message Follows]

There seems to be some interest regarding machining stuff for microwaves.

I have been considering a directional coupler for a while. So, I recently pressed may machine shop into action to make one for my in-progress 23cm amp.

I'm fairly pleased with the results. With a bit of fiddling it seems fairly easy to get between -30 and -40db coupling just by carful adjusting of the sense lines. A few hundred milliwatts out at legal limit and 3 volts or so from a diode detector. Obviously closer coupling would give higher coupling figures. Through losses really low and return loss approaching 20db. I'll take that for an on-the-fly, making it up as I went along design.

Should do to feed a LED bargraph whatsit.

If I costed my time it'd be worth about £500!

More information including images can be found at my post on Directional Coupler


Dave G6HEF
 

On Thu, Jun 24, 2021 at 11:31 AM, John

Hi John,

Directivity is about 20db but can be increased by carefully adjusting the spacing. Investigations are still to be made. There are indeed 50ohm terminations. Only 0603 resistors which probably won’t handle the power so I do intend to uprate them.

I know what you mean about making money at the job. I read the long thread on 13cm filters and thought I could help but if I charged for my time it would be serious money.

I just made a hub for my dish and it probably has sucked about a man week out of my schedule. So sometime I just go “hang, I’ll just buy it instead” and it’s easy to appreciate why somethings are expensive when you build yourself. I trust you approve!

Sometimes the satisfaction of making something I am happy with is well worth the effort.

73
Dave
G6HEF

Lemay wrote:

David

 

Good to see someone else making swarf. I wish there was a market for it ………

 

You’ve measured the through loss and the forward coupling. What about directivity ? When you’ve measured that you will know whether it will be useful to measure the SWR or RL of an aerial.

 

Can’t tell from the photos – have you terminated the two pickup lines with a low value resistor ? 50 ohms is typical.

 

Regards

 

John G4ZTR

 

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Dave G6HEF
Sent: 21 June 2021 21:23
To: UKMicrowaves@groups.io
Subject: [UKMicrowaves] By-product of swarf generation

 

[Edited Message Follows]

There seems to be some interest regarding machining stuff for microwaves.

I have been considering a directional coupler for a while. So, I recently pressed may machine shop into action to make one for my in-progress 23cm amp.

I'm fairly pleased with the results. With a bit of fiddling it seems fairly easy to get between -30 and -40db coupling just by carful adjusting of the sense lines. A few hundred milliwatts out at legal limit and 3 volts or so from a diode detector. Obviously closer coupling would give higher coupling figures. Through losses really low and return loss approaching 20db. I'll take that for an on-the-fly, making it up as I went along design.

Should do to feed a LED bargraph whatsit.

If I costed my time it'd be worth about £500!

More information including images can be found at my post on Directional Coupler