Date   

Re: MMIC

Alan Melia
 

Colin give me a little time I may have something that will do ......however I dont think it is 50in/50out. Most of the MMICs I have are good for about  13dBm max
 
Alan
G3NYK

----- Original Message -----
Sent: Monday, April 05, 2021 11:12 PM
Subject: [UKMicrowaves] MMIC

Evening all,

 

Can anyone please suggest an MMIC type device, 50ohm in – 50ohm out, for 70cm that will do at least 500mW ? Do such things exist ?     I need to get my 10m-70cm H/B transverter up to this level to drive my 13 & 9cm SG-Lab transverters. Appreciate there are other ‘not so simple’ ways of achieving this.

 

Night all,

 

Colin de G8LBS.

 

Sent from Mail for Windows 10

 


Re: MMIC

Robin Szemeti - G1YFG
 


On Mon, 5 Apr 2021 at 23:20, Stefan <comlab@...> wrote:
Hi Colin
 
A suggestion to consider, if your drive level is low, simply change the transverters input attenuator to accomodate the lower drive requirement. Maybe there is a trimpot inside for that purpose?
regarding 500mW MMIC, there are amplifers on ebay that could be used, also some cable TV amplifers can do that sort of power, but really, why making something more complex if a simple resistor change would work?
 
Stefan VK4CSD
----- Original Message -----
Sent: Tuesday, April 06, 2021 8:12 AM
Subject: [UKMicrowaves] MMIC

Evening all,

 

Can anyone please suggest an MMIC type device, 50ohm in – 50ohm out, for 70cm that will do at least 500mW ? Do such things exist ?     I need to get my 10m-70cm H/B transverter up to this level to drive my 13 & 9cm SG-Lab transverters. Appreciate there are other ‘not so simple’ ways of achieving this.

 

Night all,

 

Colin de G8LBS.

 

Sent from Mail for Windows 10

 


--
Robin Szemeti - G1YFG


Re: MMIC

Stefan
 

Hi Colin
 
A suggestion to consider, if your drive level is low, simply change the transverters input attenuator to accomodate the lower drive requirement. Maybe there is a trimpot inside for that purpose?
regarding 500mW MMIC, there are amplifers on ebay that could be used, also some cable TV amplifers can do that sort of power, but really, why making something more complex if a simple resistor change would work?
 
Stefan VK4CSD

----- Original Message -----
Sent: Tuesday, April 06, 2021 8:12 AM
Subject: [UKMicrowaves] MMIC

Evening all,

 

Can anyone please suggest an MMIC type device, 50ohm in – 50ohm out, for 70cm that will do at least 500mW ? Do such things exist ?     I need to get my 10m-70cm H/B transverter up to this level to drive my 13 & 9cm SG-Lab transverters. Appreciate there are other ‘not so simple’ ways of achieving this.

 

Night all,

 

Colin de G8LBS.

 

Sent from Mail for Windows 10

 


MMIC

Colin Ranson
 

Evening all,

 

Can anyone please suggest an MMIC type device, 50ohm in – 50ohm out, for 70cm that will do at least 500mW ? Do such things exist ?     I need to get my 10m-70cm H/B transverter up to this level to drive my 13 & 9cm SG-Lab transverters. Appreciate there are other ‘not so simple’ ways of achieving this.

 

Night all,

 

Colin de G8LBS.

 

Sent from Mail for Windows 10

 


Re: Retuning a 23cm duplexer, any hints please?

Alan Beard
 

Hi all,
Here are my mods to this 1800 MHz duplexer so far:
> www.unixservice.com.au/hamradio/repeaters/duplexers/23CMpix/
IMG_3809c.JPG
Tuning is now much easier with the M3 screws further out, out from the 4mm ID tube.

My next question is:

Can the inter-digital filter be made BandPass and BandReject?

(as we do for 2m repeaters) (photos, drawings please)

Our 20 MHz split for 23cm repeaters is pretty tight.

I see nothing on the web.

Alan VK2ZIW


On Sun, 4 Apr 2021 22:05:14 +0000 (UTC), KENT BRITAIN wrote
> Interestingly the 3rd harmonic is not exactly 3X the 430 MHz frequency, but close.
> Often easier to do the first tuning at the 430 MHz frequency,m then fine tune at the 23 cm frequency.
>
> Quite often we see the 450 MHz filters from commercial mobile radios surplus.  Most of those tune 23 cm as well.   Good luck with your project,  Kent WA5VJB/G8EMY
>
> On Sunday, April 4, 2021, 4:43:42 PM CDT, Alan Beard via groups.io <beardal@...> wrote:
>
> Thanks Kent,
>

> We have a "parrot" 23cm repeater over in the Wollongong area and changing it to Full duplex will require
> cavity filters. I acquired this one, at a good price a few years ago. Perhaps spares never used.
> Using 70cm cavities in 3rd overtone is a great idea. 
>



---------------------------------------------------
Alan VK2ZIW
Before the Big Bang, God, Sela.
OpenWebMail 2.53, nothing in the cloud.


Re: Retuning a 23cm duplexer, any hints please?

KENT BRITAIN
 

Interestingly the 3rd harmonic is not exactly 3X the 430 MHz frequency, but close.
Often easier to do the first tuning at the 430 MHz frequency,m then fine tune at the 23 cm frequency.

Quite often we see the 450 MHz filters from commercial mobile radios surplus.  Most of those tune 23 cm as well.   Good luck with your project,  Kent WA5VJB/G8EMY

On Sunday, April 4, 2021, 4:43:42 PM CDT, Alan Beard via groups.io <beardal@...> wrote:


Thanks Kent,

We have a "parrot" 23cm repeater over in the Wollongong area and changing it to Full duplex will require
cavity filters. I acquired this one, at a good price a few years ago. Perhaps spares never used.
Using 70cm cavities in 3rd overtone is a great idea. 

Robin, 

My test gear here is the new VNA the SAA V2 and a Wiltron 640 from around 1985. What I'm asking is:
Noting that both sides are just bandpass. And, as this inter-digital design is common.

How does one reduce the coupling so as to reduce the bandwidth?

As mentioned, the top screws do absolutely nothing, an imperceptible change.
I need to achieve somewhere between 5 and 10 MHz, not 20MHz.

Has anyone here any experience, either practical or with simulation?

BTW: The SAA V2 is magic.

Also, I don't know who the designer was in RFS but it's a bugger to tune with those M3 brass screws
wobbling about inside the finger ends with only 1/2mm clearance or less.

Keep smiling

Alan VK2ZIW


On Sun, 4 Apr 2021 15:28:59 +0100, Robin Szemeti - G1YFG wrote
> Depending on how it is set up, you may find the top screws are the "tuning" screws and the side screws are the coupling scews ... there are a multitude of different setups for duplexers, but if you put a sweeper on it or an analyzer with a tracking generator, you should find that as well as the pass band peaks, there may also be notches ... you may find tweaking the coupling screws effects the notches while the tuning screws shift the passbands. The passbands are usually fairly broad, tweaking those is simple enough, althoug a VNA will help you optimise the match ... the notches (if the design has notches ... ) are usually very sharp and sensitive!
>
> On Sun, 4 Apr 2021 at 11:58, KENT BRITAIN <WA5VJB@...> wrote:
>

>
> For what it's worth, we often retune 450-470 MHz duplexers to 430 MHz or so, then fine tune them on their 3rd Harmonic.   Many of the Texas 23 cm repeaters are using UHF duplexers. 
>
> On Sunday, April 4, 2021, 12:44:57 AM CDT, Alan Beard via groups.io <beardal=unixservice.com.au@groups.io> wrote:
>
> Hi all,
>
> I've just attempted to retune this duplexer from Radio Frequency Systems P/L.
>
> Model: CP1800-I42
>
> Originally on 1710 and 1910 MHz. It tuned down to 1273 and 1293 MHz OK but
>
> kept the same "channel" bandwidth of about 20 MHz. (the width of the pass band)
>
> So, it's skirts only attenuate 45db or so the Tx carrier and/or the
>
> Tx spurii.
>
> I note the inter digital coupling screws do nothing and I mean nothing
>
> to reduce the coupling and thus the filter bandwidth. (the three on the
>
> left and right ends of the top cover)
>
> Has anyone any thoughts on making it useful for our 20MHz split 23cm
>
> repeaters?
>
> ---------------------------------------------------
>
> Alan VK2ZIW
>
> Before the Big Bang, God, Sela.
>
> OpenWebMail 2.53, nothing in the cloud.
>
>

> --
> Robin Szemeti - G1YFG

---------------------------------------------------
Alan VK2ZIW
Before the Big Bang, God, Sela.
OpenWebMail 2.53, nothing in the cloud.


Re: Retuning a 23cm duplexer, any hints please?

Alan Beard
 

Thanks Kent,

We have a "parrot" 23cm repeater over in the Wollongong area and changing it to Full duplex will require
cavity filters. I acquired this one, at a good price a few years ago. Perhaps spares never used.
Using 70cm cavities in 3rd overtone is a great idea. 

Robin, 

My test gear here is the new VNA the SAA V2 and a Wiltron 640 from around 1985. What I'm asking is:
Noting that both sides are just bandpass. And, as this inter-digital design is common.

How does one reduce the coupling so as to reduce the bandwidth?

As mentioned, the top screws do absolutely nothing, an imperceptible change.
I need to achieve somewhere between 5 and 10 MHz, not 20MHz.

Has anyone here any experience, either practical or with simulation?

BTW: The SAA V2 is magic.

Also, I don't know who the designer was in RFS but it's a bugger to tune with those M3 brass screws
wobbling about inside the finger ends with only 1/2mm clearance or less.

Keep smiling

Alan VK2ZIW


On Sun, 4 Apr 2021 15:28:59 +0100, Robin Szemeti - G1YFG wrote
> Depending on how it is set up, you may find the top screws are the "tuning" screws and the side screws are the coupling scews ... there are a multitude of different setups for duplexers, but if you put a sweeper on it or an analyzer with a tracking generator, you should find that as well as the pass band peaks, there may also be notches ... you may find tweaking the coupling screws effects the notches while the tuning screws shift the passbands. The passbands are usually fairly broad, tweaking those is simple enough, althoug a VNA will help you optimise the match ... the notches (if the design has notches ... ) are usually very sharp and sensitive!
>
> On Sun, 4 Apr 2021 at 11:58, KENT BRITAIN <WA5VJB@...> wrote:
>

>
> For what it's worth, we often retune 450-470 MHz duplexers to 430 MHz or so, then fine tune them on their 3rd Harmonic.   Many of the Texas 23 cm repeaters are using UHF duplexers. 
>
> On Sunday, April 4, 2021, 12:44:57 AM CDT, Alan Beard via groups.io <beardal=unixservice.com.au@groups.io> wrote:
>
> Hi all,
>
> I've just attempted to retune this duplexer from Radio Frequency Systems P/L.
>
> Model: CP1800-I42
>
> Originally on 1710 and 1910 MHz. It tuned down to 1273 and 1293 MHz OK but
>
> kept the same "channel" bandwidth of about 20 MHz. (the width of the pass band)
>
> So, it's skirts only attenuate 45db or so the Tx carrier and/or the
>
> Tx spurii.
>
> I note the inter digital coupling screws do nothing and I mean nothing
>
> to reduce the coupling and thus the filter bandwidth. (the three on the
>
> left and right ends of the top cover)
>
> Has anyone any thoughts on making it useful for our 20MHz split 23cm
>
> repeaters?
>
> ---------------------------------------------------
>
> Alan VK2ZIW
>
> Before the Big Bang, God, Sela.
>
> OpenWebMail 2.53, nothing in the cloud.
>
>

> --
> Robin Szemeti - G1YFG

---------------------------------------------------
Alan VK2ZIW
Before the Big Bang, God, Sela.
OpenWebMail 2.53, nothing in the cloud.


Re: Retuning a 23cm duplexer, any hints please?

Robin Szemeti - G1YFG
 

Depending on how it is set up, you may find the top screws are the "tuning" screws and the side screws are the coupling scews ... there are a multitude of different setups for duplexers, but if you put a sweeper on it or an analyzer with a tracking generator, you should find that as well as the pass band peaks, there may also be notches ... you may find tweaking the coupling screws effects the notches while the tuning screws shift the passbands. The passbands are usually fairly broad, tweaking those is simple enough, althoug a VNA will help you optimise the match ... the notches (if the design has notches ... ) are usually very sharp and sensitive!



On Sun, 4 Apr 2021 at 11:58, KENT BRITAIN <WA5VJB@...> wrote:
For what it's worth, we often retune 450-470 MHz duplexers to 430 MHz or so, then fine tune them on their 3rd Harmonic.   Many of the Texas 23 cm repeaters are using UHF duplexers. 

On Sunday, April 4, 2021, 12:44:57 AM CDT, Alan Beard via groups.io <beardal=unixservice.com.au@groups.io> wrote:


Hi all,

I've just attempted to retune this duplexer from Radio Frequency Systems P/L.
Model: CP1800-I42

Originally on 1710 and 1910 MHz. It tuned down to 1273 and 1293 MHz OK but
kept the same "channel" bandwidth of about 20 MHz. (the width of the pass band)

So, it's skirts only attenuate 45db or so the Tx carrier and/or the
Tx spurii.

I note the inter digital coupling screws do nothing and I mean nothing
to reduce the coupling and thus the filter bandwidth. (the three on the
left and right ends of the top cover)

Has anyone any thoughts on making it useful for our 20MHz split 23cm
repeaters?


---------------------------------------------------
Alan VK2ZIW
Before the Big Bang, God, Sela.
OpenWebMail 2.53, nothing in the cloud.







--
Robin Szemeti - G1YFG


Re: Retuning a 23cm duplexer, any hints please?

KENT BRITAIN
 

For what it's worth, we often retune 450-470 MHz duplexers to 430 MHz or so, then fine tune them on their 3rd Harmonic.   Many of the Texas 23 cm repeaters are using UHF duplexers. 

On Sunday, April 4, 2021, 12:44:57 AM CDT, Alan Beard via groups.io <beardal@...> wrote:


Hi all,

I've just attempted to retune this duplexer from Radio Frequency Systems P/L.
Model: CP1800-I42

Originally on 1710 and 1910 MHz. It tuned down to 1273 and 1293 MHz OK but
kept the same "channel" bandwidth of about 20 MHz. (the width of the pass band)

So, it's skirts only attenuate 45db or so the Tx carrier and/or the
Tx spurii.

I note the inter digital coupling screws do nothing and I mean nothing
to reduce the coupling and thus the filter bandwidth. (the three on the
left and right ends of the top cover)

Has anyone any thoughts on making it useful for our 20MHz split 23cm
repeaters?


---------------------------------------------------
Alan VK2ZIW
Before the Big Bang, God, Sela.
OpenWebMail 2.53, nothing in the cloud.







Retuning a 23cm duplexer, any hints please?

Alan Beard
 

Hi all,

I've just attempted to retune this duplexer from Radio Frequency Systems P/L.
Model: CP1800-I42

Originally on 1710 and 1910 MHz. It tuned down to 1273 and 1293 MHz OK but
kept the same "channel" bandwidth of about 20 MHz. (the width of the pass band)

So, it's skirts only attenuate 45db or so the Tx carrier and/or the
Tx spurii.

I note the inter digital coupling screws do nothing and I mean nothing
to reduce the coupling and thus the filter bandwidth. (the three on the
left and right ends of the top cover)

Has anyone any thoughts on making it useful for our 20MHz split 23cm
repeaters?


---------------------------------------------------
Alan VK2ZIW
Before the Big Bang, God, Sela.
OpenWebMail 2.53, nothing in the cloud.


Portable Operation in UKuG Contests

John Quarmby
 

The next UK Microwave Group contest is the LowBand event on 11th April from 10:00 - 16:00 GMT (11:00 - 17:00 BST) on the 1296, 2300, 2320, and 3400MHz bands.

As some of the lock down rules have been relaxed, portable entries will now be accepted.

73

John G3XDY
UKuG Contest Manager


--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus


Re: Where is the focal point of an LNB?

Chris Wilson
 

Hello Mike,

Thursday, April 1, 2021

Thanks Mike and to all who replied, making it adjustable seems the easiest and most practical way, so that's what I will do :)


Best regards,
Chris 2E0ILY mailto:chris@chriswilson.tv


MW> PS - 6 photos of the feed but not one of the actual dish? Given
MW> it is a tripod feed I would suggest you make the mount adjustable.
MW> Then you can optimise it in situ.


Re: Where is the focal point of an LNB?

Chris Wilson
 

Hello Neil,

Thursday, April 1, 2021

This is what I was afraid of Neil. The set up worked fine, but terrestrial satellites and a 1.8 meter dish gives a lot of leeway, so I will see how I can give things some adjustability, thank you.

Best regards,
Chris 2E0ILY mailto:chris@chriswilson.tv


NSG> With unknown dishes, I don't trust the current location of the
NSG> feedpoint, I make a temporary bracket which can slide along the
NSG> LNB axis and use sun noise to find the optimal position, verify
NSG> using a longish optical path, then measure the position and make
NSG> a permanent clamp with a couple of cm adjustment.

NSG> Neil G4DBN
NSG>
NSG>
NSG>
NSG>


Re: Where is the focal point of an LNB?

Neil Smith G4DBN
 

Hi Keith, it's a Pickett-Potter I made to the WA6KBL design for 3cm, linear dual-mode, fed with WR90 through a tuned oval iris

Neil

On 02/04/2021 14:14, Keith wrote:
Neil,
Is that feed one of the RF Hamdesign horn feeds ?
I was originally looking at that design for 8.45 ghz, but have since gone to a squeezed tube polariser.
Cheers
Keith
VK6KB / VK6EME


Re: Where is the focal point of an LNB?

Keith
 

Neil, 
Is that feed one of the RF Hamdesign horn feeds ?
I was originally looking at that design for 8.45 ghz, but have since gone to a squeezed tube polariser.
Cheers
Keith 
VK6KB / VK6EME


Re: Looking for data on 23cm G3JVL 47-ele loop yagi.

andrew marshall
 

Hi Andy,

Thank you for your reply. That's saved me having to d/l it.

73,
Andrew.


Re: Looking for data on 23cm G3JVL 47-ele loop yagi.

andrew marshall
 

Hi John,

Thank you for your reply. I'll do a search for that company and see whether there's a close-enough antenna to the 'JVL 47-ele.

73,
Andrew.


Re: Looking for data on 23cm G3JVL 47-ele loop yagi.

andrew marshall
 

Hi Kent,

Thank you for your reply. I'll use 20dBi as input to the RSGB calculator and see if I'm compliant with 10W RF into 8m of H100.

73,
Andrew.


Re: Looking for data on 23cm G3JVL 47-ele loop yagi.

John Lemay
 

Andrew

 

Directive Systems in the USA sell a range of loop yagis and their specification includes gain. You will probably find one of a comparable size to yours.

 

John G4ZTR

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of andrew marshall
Sent: 01 April 2021 17:55
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Looking for data on 23cm G3JVL 47-ele loop yagi.

 

Hi Stuart,

Thanks for your reply.

I'll do a search for the loop quad calc program and see whether there's a way forward there. For security reasons my Net-connected machines run Linux so if the program needs Windows that might be a problem - we'll see.

73,

Andrew, G8BUR, M0MAA.


Re: Looking for data on 23cm G3JVL 47-ele loop yagi.

KENT BRITAIN
 

20 dBi gain is typical   15 deg 3 dB beamwidth is typical

Plus or Minus a few seasons of weathering.

Kent


On Thursday, April 1, 2021, 11:54:39 AM CDT, andrew marshall <g8bur@...> wrote:


Hi Stuart,

Thanks for your reply.

I'll do a search for the loop quad calc program and see whether there's a way forward there. For security reasons my Net-connected machines run Linux so if the program needs Windows that might be a problem - we'll see.

73,
Andrew, G8BUR, M0MAA.

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