Date   

Re: Feedthrough capacitor wanted

John Lemay
 

Roger

That would be brilliant thanks !

I'll drop you my address on a PM.

John

-----Original Message-----
From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Roger Ray via groups.io
Sent: 10 March 2021 08:17
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Feedthrough capacitor wanted

Hi John,

I have got a few hundred 1000pF. I believe are 8/32. ie same size but will not fit a 4mm nut. I can send you a few.

Roger
On 10 Mar 2021, at 07:59, John Lemay <john@carltonhouse.eclipse.co.uk> wrote:

I'm looking for just one feedthrough capacitor, to replace a failed item:

The most important feature is the screw-in thread, which needs to be 8-32,
to fit the tapped hole in my case. Overall length about 20mm. Capacitance
value is unimportant and the working voltage only needs to be 24v.

Anyone got one tucked away in the spare component drawer ?

Tip: 8-32 thread looks like M4 at first glance.

Thanks

John G4ZTR



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Re: Feedthrough capacitor wanted

Roger Ray
 

Hi John,

I have got a few hundred 1000pF. I believe are 8/32. ie same size but will not fit a 4mm nut. I can send you a few.

Roger

On 10 Mar 2021, at 07:59, John Lemay <john@carltonhouse.eclipse.co.uk> wrote:

I'm looking for just one feedthrough capacitor, to replace a failed item:

The most important feature is the screw-in thread, which needs to be 8-32,
to fit the tapped hole in my case. Overall length about 20mm. Capacitance
value is unimportant and the working voltage only needs to be 24v.

Anyone got one tucked away in the spare component drawer ?

Tip: 8-32 thread looks like M4 at first glance.

Thanks

John G4ZTR



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https://www.avg.com






Re: DB6NT sequencer

John Lemay
 

Hi Pete

 

Very long time no speak ! Hope you’re well.

 

Yes, checked the diode and it was OK, but replaced it anyway, being cheap and easy to do.

 

Regards

 

John G4ZTR

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Peter Burgess via groups.io
Sent: 09 March 2021 21:45
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] DB6NT sequencer

 

Hi John

Check that the protection diode across the relay has not gone open circuit.

Peter
G4BCH


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Feedthrough capacitor wanted

John Lemay
 

I'm looking for just one feedthrough capacitor, to replace a failed item:

The most important feature is the screw-in thread, which needs to be 8-32,
to fit the tapped hole in my case. Overall length about 20mm. Capacitance
value is unimportant and the working voltage only needs to be 24v.

Anyone got one tucked away in the spare component drawer ?

Tip: 8-32 thread looks like M4 at first glance.

Thanks

John G4ZTR



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https://www.avg.com


Re: 10GHz Feedhorn 60cm offset dish, looking for

Tim, VK2XAX
 

And... if you want 24GHz as well, you might ask W1GHZ about the availability of his horns.

http://w1ghz.org/

http://w1ghz.org/new/LPF10.pdf

regards

Tim


--
VK2XAX : QF56if : ITU59 : CQ30 : BMARC : WIA


Re: DB6NT sequencer

Alan Melia
 


.......or more likely short circuit. Very high very short spikes can cause the PIV to reduce, then eventually the first ''relay off'' condition melts the diode. Fast good diodes are not the best snubbers, you require a dode with a fair bit of themal inertia. Particularly when techs used to ''routine'' Strowger :-))
 
Alan
G3NYK
 

----- Original Message -----
Sent: Tuesday, March 09, 2021 9:45 PM
Subject: Re: [UKMicrowaves] DB6NT sequencer

Hi John

Check that the protection diode across the relay has not gone open circuit.

Peter
G4BCH


Re: DB6NT sequencer

Peter Burgess
 

Hi John

Check that the protection diode across the relay has not gone open circuit.

Peter
G4BCH


Re: DB6NT sequencer

John Lemay
 

Geoff

 

Thanks for the suggestion, and yes, I think the series of sequencers work on similar principles, with devices of small or large capability.

 

You asked if I am sure the devices have failed – actually I’m not sure – and that idea set me on the path of simple multimeter checks. I find that the unused device and the two supposedly failed devices give similar resistance measurements. But ……… the one in use at present does not.

 

I have the sequencer in a machined aluminium case, with feedthrough capacitors for all connections. Now I’ve disconnected everything from the feedthroughs, and one of them measures about 1k ohm to chassis. It’s the one on relay –ve. How weird is that ?

 

I’m calling it a day now, but at last I feel I may have located the problem. I really don’t have much hair left ………..

 

Regards

 

John

 

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of geoffrey pike via groups.io
Sent: 09 March 2021 21:10
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] DB6NT sequencer

 

Hi John,

I have only SEQ2 details but they may be similar. So the gate is controlled via 3v zener. Have you monitored the gate

voltage when you let the ptt go?

Are you sure the other two IRF520s have actually failed.

Good news is that IRF520s are cheap until you find the fault.

Geoff

GI0GDP

 

On Tuesday, 9 March 2021, 20:32:06 GMT, John Lemay <john@...> wrote:

 

 

Hello all

 

I'm not having much luck lately .......

 

My 13cms masthead system uses a DB6NT sequencer SEQ 4 to switch a 28v

changeover relay. At the weekend I had no receive on 13cms, transmit was

fine.

 

Delving into the box today it seems that the switching FET, an IRF520 has

gone "leaky" between drain and source. It pulls the relay into transmit

nicely, with almost 0v on the drain, but on receive there is enough voltage

remaining to hold the relay energised.

 

I've replaced the FET, twice, today and failure of the device is instant but

without drama.

 

Disconnecting the relay from the sequencer and running the relay to an

external power supply, it switches just as it should.

 

Any suggestions as to the likely cause of my sequencer problem? I have just

one FET remaining ........

 

Thanks

 

John G4ZTR

 

 

 

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Re: DB6NT sequencer

geoffrey pike
 

Hi John,
I have only SEQ2 details but they may be similar. So the gate is controlled via 3v zener. Have you monitored the gate
voltage when you let the ptt go?
Are you sure the other two IRF520s have actually failed.
Good news is that IRF520s are cheap until you find the fault.
Geoff
GI0GDP

On Tuesday, 9 March 2021, 20:32:06 GMT, John Lemay <john@...> wrote:


Hello all

I'm not having much luck lately .......

My 13cms masthead system uses a DB6NT sequencer SEQ 4 to switch a 28v
changeover relay. At the weekend I had no receive on 13cms, transmit was
fine.

Delving into the box today it seems that the switching FET, an IRF520 has
gone "leaky" between drain and source. It pulls the relay into transmit
nicely, with almost 0v on the drain, but on receive there is enough voltage
remaining to hold the relay energised.

I've replaced the FET, twice, today and failure of the device is instant but
without drama.

Disconnecting the relay from the sequencer and running the relay to an
external power supply, it switches just as it should.

Any suggestions as to the likely cause of my sequencer problem? I have just
one FET remaining ........

Thanks

John G4ZTR



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This email has been checked for viruses by AVG.







Re: 10GHz Feedhorn 60cm offset dish, looking for

Neil Smith G4DBN
 

Motivations were:

1) I have a load of Rexolite 1422 that I need to use up

2) Inherently waterproof and spider-resistant.

3) Small enough to fit alongside a similar model on 5.7 GHz with 2 degrees of dish nod to swap bands

It isn't going to be any better than a well-designed W2IMU or Pickett-Potter or corrugated-choke horn in terms of sidelobe suppression, but it is reasonably easy to control sidelobes and set a decent edge taper.

I'll make half a dozen and see how they look on a rotary mount, and then see what sort of sun noise I get when compared with a known horn.

Neil

On 09/03/2021 20:53, Colin Ranson wrote:

Looks nice Neil – yo a star !  as my brummy missus would say.  I don’t think I can get away with anything bigger than a Zone 2 elliptical – my house is stating to look like the Mothership in Battlestar Galactica !

 

73’s    Colin.

 

Sent from Mail for Windows 10

 

From: Neil Smith G4DBN
Sent: 09 March 2021 19:18
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] 10GHz Feedhorn 60cm offset dish, looking for

 

I'm making some lensed dielspike horns with a collar to fit a 40mm feedhorn clamp on an offset dish, they have an aluminium body with an SMA connector and a truncated conical Rexolite 1422 lens similar to the ones designed by HB9PZK for QO-100.  The cone angle is calculated to give a 12dB edge taper on a typical 80cm offset dish

They are sealed units and designed to be left out in the rain. I haven't tried doing them with an N connector mainly on cost grounds, but it should be feasible to use an N connector with a reduced SMA base in exactly the same unit, so long as it has a 4.06 mm PTFE sleeve.  You could probably modify any SMA-equipped transition to use one of these N types (perhaps from someone cheaper than H&S!)



Re: 10GHz Feedhorn 60cm offset dish, looking for

Colin Ranson
 

Looks nice Neil – yo a star !  as my brummy missus would say.  I don’t think I can get away with anything bigger than a Zone 2 elliptical – my house is stating to look like the Mothership in Battlestar Galactica !

 

73’s    Colin.

 

Sent from Mail for Windows 10

 

From: Neil Smith G4DBN
Sent: 09 March 2021 19:18
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] 10GHz Feedhorn 60cm offset dish, looking for

 

I'm making some lensed dielspike horns with a collar to fit a 40mm feedhorn clamp on an offset dish, they have an aluminium body with an SMA connector and a truncated conical Rexolite 1422 lens similar to the ones designed by HB9PZK for QO-100.  The cone angle is calculated to give a 12dB edge taper on a typical 80cm offset dish

They are sealed units and designed to be left out in the rain. I haven't tried doing them with an N connector mainly on cost grounds, but it should be feasible to use an N connector with a reduced SMA base in exactly the same unit, so long as it has a 4.06 mm PTFE sleeve.  You could probably modify any SMA-equipped transition to use one of these N types (perhaps from someone cheaper than H&S!)

This horn is aimed at folks who are building the F6BVA transverter and don't want to use waveguide.  I haven't announced it yet as I'm still optimising the tapers and pin position. Target price is under £30.

Neil G4DBN

Something like this:

with the lenses being similar to those HB9PZKs I made last year

or perhaps just with a long rear taper like these I made:

On 09/03/2021 15:28, Mike Willis wrote:

You can make one fairly easily out of plumbing fittings, but if you are one of those who has to buy and nobody has a spare the usual suspects can provide. RFHAM, Procom. Passion Radio...

 

 


Re: DB6NT sequencer

ian hope (2E0IJH)
 

You having about as much luck as me, I've had no changeover on my 2m system, 13.4v there on or off load, but relay wouldn't switch, works fine on bench, in the end meggered the cable less than 100 ohms between cores, No damage, ends clean, cut it half and several pints of water poured out a 12 core YY cable, figure that
 
Ian
M5IJH

 
 
Sent: Tuesday, March 09, 2021 at 8:31 PM
From: "John Lemay" <john@...>
To: UKMicrowaves@groups.io
Subject: [UKMicrowaves] DB6NT sequencer
Hello all

I'm not having much luck lately .......

My 13cms masthead system uses a DB6NT sequencer SEQ 4 to switch a 28v
changeover relay. At the weekend I had no receive on 13cms, transmit was
fine.

Delving into the box today it seems that the switching FET, an IRF520 has
gone "leaky" between drain and source. It pulls the relay into transmit
nicely, with almost 0v on the drain, but on receive there is enough voltage
remaining to hold the relay energised.

I've replaced the FET, twice, today and failure of the device is instant but
without drama.

Disconnecting the relay from the sequencer and running the relay to an
external power supply, it switches just as it should.

Any suggestions as to the likely cause of my sequencer problem? I have just
one FET remaining ........

Thanks

John G4ZTR



--
This email has been checked for viruses by AVG.
https://www.avg.com





 


DB6NT sequencer

John Lemay
 

Hello all

I'm not having much luck lately .......

My 13cms masthead system uses a DB6NT sequencer SEQ 4 to switch a 28v
changeover relay. At the weekend I had no receive on 13cms, transmit was
fine.

Delving into the box today it seems that the switching FET, an IRF520 has
gone "leaky" between drain and source. It pulls the relay into transmit
nicely, with almost 0v on the drain, but on receive there is enough voltage
remaining to hold the relay energised.

I've replaced the FET, twice, today and failure of the device is instant but
without drama.

Disconnecting the relay from the sequencer and running the relay to an
external power supply, it switches just as it should.

Any suggestions as to the likely cause of my sequencer problem? I have just
one FET remaining ........

Thanks

John G4ZTR



--
This email has been checked for viruses by AVG.
https://www.avg.com


Re: 10GHz Feedhorn 60cm offset dish, looking for

Neil Smith G4DBN
 

I'm making some lensed dielspike horns with a collar to fit a 40mm feedhorn clamp on an offset dish, they have an aluminium body with an SMA connector and a truncated conical Rexolite 1422 lens similar to the ones designed by HB9PZK for QO-100.  The cone angle is calculated to give a 12dB edge taper on a typical 80cm offset dish

They are sealed units and designed to be left out in the rain. I haven't tried doing them with an N connector mainly on cost grounds, but it should be feasible to use an N connector with a reduced SMA base in exactly the same unit, so long as it has a 4.06 mm PTFE sleeve.  You could probably modify any SMA-equipped transition to use one of these N types (perhaps from someone cheaper than H&S!)

This horn is aimed at folks who are building the F6BVA transverter and don't want to use waveguide.  I haven't announced it yet as I'm still optimising the tapers and pin position. Target price is under £30.

Neil G4DBN

Something like this:

with the lenses being similar to those HB9PZKs I made last year

or perhaps just with a long rear taper like these I made:

On 09/03/2021 15:28, Mike Willis wrote:
You can make one fairly easily out of plumbing fittings, but if you are one of those who has to buy and nobody has a spare the usual suspects can provide. RFHAM, Procom. Passion Radio...


Re: 10GHz Feedhorn 60cm offset dish, looking for

Colin Ranson
 

Hi John, I must be on your wavelength !  I will soon be constructing same with 22mm tube but with ‘horn’ as pictured. Forget its type.  Its 75mm across the mouth. Any ‘rough’ idea as to gain on its own? Hoping this will work ok with a 60cm (Zone 2) elliptical dish.

 

Regards  & 73’s  de G8LBS

 

Sent from Mail for Windows 10

 

From: John Quarmby via groups.io
Sent: 09 March 2021 18:04
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] 10GHz Feedhorn 60cm offset dish, looking for

 

If you want a coax fed version of the G3PHO feed then you could try P111/112 of this pdf from UKuG Backscatter:

https://www.microwavers.org/files/backscatter/3_Antennas.pdf

I have been using this feed design for 20+ years with good results.

73

John G3XDY

On 09/03/2021 16:58, Mike Willis wrote:

The third hit in google for 10 ghz dish feed is this: http://www.g3pho.free-online.co.uk/microwaves/horn.htm

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Virus-free. www.avast.com

 


Re: 10GHz Feedhorn 60cm offset dish, looking for

John Quarmby
 

If you want a coax fed version of the G3PHO feed then you could try P111/112 of this pdf from UKuG Backscatter:

https://www.microwavers.org/files/backscatter/3_Antennas.pdf

I have been using this feed design for 20+ years with good results.

73

John G3XDY

On 09/03/2021 16:58, Mike Willis wrote:
The third hit in google for 10 ghz dish feed is this: http://www.g3pho.free-online.co.uk/microwaves/horn.htm

--
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Virus-free. www.avast.com


Re: 10GHz Feedhorn 60cm offset dish, looking for

Mike Willis
 

The third hit in google for 10 ghz dish feed is this: http://www.g3pho.free-online.co.uk/microwaves/horn.htm

--
Mike G0MJW


Re: 10GHz Feedhorn 60cm offset dish, looking for

Maarten PA0MHE
 

Hi Mike,


Nothing against home plumbing :) As long a the expected result is good, I saw versions but for that you need a lathe.
Can you please advice a design for such a ~~44degree ?

73's Maarten


Re: Nano VNA SAA-2N and G3XDY QRO filter

Brian Howie GM4DIJ
 

In message <ed06f523-2948-2942-43b1-98f920dd8edf@btinternet.com>, John Quarmby via groups.io <g3xdy=btinternet.com@groups.io> writes

I tried it on a dummy load. I seems to be OK until about 3.8 then it's a bit noisy as was mentioned. The trace was a bit less lumpy after I calibrated it up to 4GHz.

Cheers

Brian GM4DIJ

Just select 4GHz as the upper frequency limit when setting the sweep range and do a calibration run prior to measurement. Dynamic range and accuracy may be a bit below spec but it does provide a good indication of what is going on.

73

John G3XDY

On 09/03/2021 11:23, Brian Howie GM4DIJ wrote:
In message <29724.1615033813404469843@groups.io>, Dave G1EHF via groups.io <david.j.austen=btinternet.com@groups.io> writes
The VNA SAA-2 series use the ADF4350 as source oscillators, which in
theory will go to 4.4 GHz. Mine goes easily to 4 GHz, although the
noise floor does start to increase above 3 GHz. That said, it can
characterise a 9 cm filter or antenna easily if you're not after 70 dB
of dynamic range!
73, Dave G1EHF
I got a SAA-2N recently . Is there anything special  you have to do to get it to go up there ?

Cheers

Brian GM4DIJ
--
Brian Howie


Re: 10GHz Feedhorn 60cm offset dish, looking for

Mike Willis
 

You can make one fairly easily out of plumbing fittings, but if you are one of those who has to buy and nobody has a spare the usual suspects can provide. RFHAM, Procom. Passion Radio...
--
Mike G0MJW

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