BATC Forum

As we know, filtering before the MiniTiouner is advisable, especially in challenging RF environments. RF cavity filters are best, but not always practical to carry about on the lower bands.

For 2m its hard to beat the filtering in the DG8 pre-amp from GM3SEK. http://www.ifwtech.co.uk/g3sek/vhfdx/dg8-preamp-v7.pdf though I am not sure if these are still available.

70cm and up inter-digital filters become a manageable option. W1GHZ has some info on filters using Altoids tins. I know several people have had success with these: http://www.w1ghz.org/filter/Altoids_Tin_Filters.pdf
I have also been looking at the cheap LNA/SAW Filters from Ebay (e.g. item number:131574529568) Mine took a long time to arrive and when it did, it came without any device fitted and didn't look much like the photo in the advert.


Buyer beware. However, after shorting out the missing device the performance is not too bad - mine is on 70cm. Other bands are available but not easily.


For more info see the wiki https://wiki.batc.tv/Filters

Mike

Hi Mike,

Same here, I ordered for my 146.5 to 437 mixer project...

http://www.batc.org.uk/forum/viewtopic. ... 611#p12611

Mine just arrived, 262543494592, not same as picture, only one amp on input no device, said he would resend

The seller here, 131574529568 Pic Attached, he did email and said delay but both came last week, amp on in and out.

Will try a in stock device, also as a straight filter.

In my case.... Poor supplier 262543494592 no longer in use... Good supplier 131574529568

Peter

John G7JTT bought his unit over today - looks like the picture in Peter's post and has both devices plus the SAW filter fitted

We measured it as having 38 dB gain and sub 1 dB noise figure so reasonable performance but as can be seen below the SAW filter is 20 MHz wide - this is probably too wide to use on 70cms without a tighter (mechanical) filter in line as well.
It could be feasible to remove the SAW and take 50 ohm leads out to an external filter such as http://www.w1ghz.org/filter/Combline_Fi ... nd_UHF.pdf

73 Noel