[amsat-bb] Shoppinglist

[Wendy and Terry Osborne]

Hi Hans,

If you have a plenty of RG213 and suitable connectors, you could try making 
a Coax stub filter.
You need a cable length that is an odd multiple of a quarter wave length 
long at the FM Tx frequency
and an even multiple of a quarter wave at the frequency that you want (2M 
/70CMs).
A single RG213 stub would have about 25dB of rejection and would pass 100 
Watts OK.
You just need a coax T connector and some matching connectors.
To trim the stub, use a set of garden secateurs.
If you have a Bao feng or similar radio you could use that on the FM band 
attached to your T and trim
the stub for minimum signal on the unwanted Tx frequency.

I haven't run the calculations for how long the stub should be but if it's 
useful I could do so.

73,
Terry Osborne ZL2BAC


-----Original Message----- 
From: Hans BX2ABT
Sent: Thursday, March 14, 2019 12:33 AM
To: amsat-bb at amsat.org
Subject: [amsat-bb] Shoppinglist

My sis-in-law will be visiting from the States soon and I usually make
her bring some stuff for me so I can save on freight costs. She will
definitely bring an Arrow Antenna so I can start some portable
operations. A Sony voice recorder is also on my list, as well as some
coax cable (RG-400 is what I'm thinking of. Really expensive here).
Don't have a budget for much more, but since I have a clear
line-of-sight to some 10 kW FM transmitters from my QTH I thought I
should at least get a good FM-band notch filter.

Any recommendations on where to buy this in the US? I haven't found
anything when I googled, not even a lot of 2/70 band pass filters, or
low pass filters to prevent desensing on 70 cm. My own creations have a
too high insertion loss, so this time I really want something a bit more
professional and something that can handle at least 100 Watts of power.
Any recommendations are welcome. Cheers. --Hans BX2ABT


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