70cm SAW filter

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G4GHD
Posts: 40
Joined: Sun Nov 12, 2017 12:18 am

70cm SAW filter

Post by G4GHD » Tue Feb 05, 2019 10:29 pm

Has anyone used this (or similar) on receive in conjunction with a MiniTiouner?
https://www.ebay.co.uk/itm/70cm-430-440 ... 4003655576

I'm thinking this is, although better than nothing, probably a tad too wide, as I live in a pretty RF congested area.
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F6DZP
Posts: 217
Joined: Fri May 27, 2011 9:59 am

Re: 70cm SAW filter

Post by F6DZP » Wed Feb 06, 2019 8:11 am

Hello,

I use this filter for transmission mode after a LimeSDRMini or a Pluto, but not with a MiniTiouner. Its bandwidth is acceptable to filter 437MHz harmonics but not disturbing signals around 437 MHz.
spectre filtre saw 425MHz-446MHz.jpg
spectre filtre saw 425MHz-446MHz.jpg (78.78 KiB) Viewed 5071 times

Jean-Pierre F6DZP
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g0mjw
Posts: 2346
Joined: Sat Sep 20, 2014 9:15 am

Re: 70cm SAW filter

Post by g0mjw » Wed Feb 06, 2019 8:25 am

Hi Jean-Pierre

How does the group delay vary across the bandwidth?

Mike
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F6DZP
Posts: 217
Joined: Fri May 27, 2011 9:59 am

Re: 70cm SAW filter

Post by F6DZP » Wed Feb 06, 2019 9:35 am

Interesting question but I have not look at the group delay for this chip, just use it only for low SR and low level. I have not observed any difference with the signal other than 2dB loss, so go further without studying the group delay.

This is a TA1408A
You can find the datasheet here:
https://www.golledge.com/media/2551/mp04694.pdf

You can buy this chip by 5 units on AliExpress website
https://www.aliexpress.com/item/Origina ... 44173.html

Jean-Pierre F6DZP
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G4FRE
Posts: 197
Joined: Fri May 26, 2017 6:57 am

Re: 70cm SAW filter

Post by G4FRE » Wed Feb 06, 2019 10:34 am

I Use

https://www.ebay.co.uk/itm/450-Mhz-Heli ... ctupt=true

in front of my minituner when not using the mhp which has onboard helicals. Tunes 430-440Mhz without issue

Dave
G4FRE
G4GHD wrote: ↑
Tue Feb 05, 2019 10:29 pm
 Has anyone used this (or similar) on receive in conjunction with a MiniTiouner?
https://www.ebay.co.uk/itm/70cm-430-440 ... 4003655576

I'm thinking this is, although better than nothing, probably a tad too wide, as I live in a pretty RF congested area.
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g0mjw
Posts: 2346
Joined: Sat Sep 20, 2014 9:15 am

Re: 70cm SAW filter

Post by g0mjw » Wed Feb 06, 2019 11:20 am

I have something similar in a Habamp, an LNA designed for high altitude balloon reception - which I use for DATV on 70cms.

See https://store.uputronics.com/index.php? ... duct_id=53

for a more recent implementation.

Mike
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G4GHD
Posts: 40
Joined: Sun Nov 12, 2017 12:18 am

Re: 70cm SAW filter

Post by G4GHD » Wed Feb 13, 2019 1:19 pm

Thanks for the comments and suggestions :)
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ea3ta
Posts: 6
Joined: Fri May 04, 2018 7:21 pm

Re: 70cm SAW filter

Post by ea3ta » Sat Feb 16, 2019 11:47 am

Some in EA3 we are using with minitiouner and with good results this:

https://www.tindie.com/products/gpio/43 ... bandwidth/
73, Juan EA3TA
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PE5PVB
Posts: 155
Joined: Sun Sep 02, 2012 6:51 pm

Re: 70cm SAW filter

Post by PE5PVB » Tue Feb 19, 2019 10:21 am

I've used this one in the past in several 70cm projects: https://nl.mouser.com/ProductDetail/ABR ... jkZw%3d%3d
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