Topband: RF attenuators

[Julius Fazekas]

Haven't closely followed this thread, but here's a pretty easy to reproduce splitter, can't imagine the parts costing more than $10, if you're a decent scrounger even less:

http://wiki.contesting.com/index.php/VP6DX_receiving_antennas#Bandpass_filter-splitter

Julius Fazekas

N2WN



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Elecraft K2     #4455

Elecraft K3/100 #366

Elecraft K3/100 #1875

--- On Wed, 8/24/11, Jim Brown <jim at audiosystemsgroup.com> wrote:

From: Jim Brown <jim at audiosystemsgroup.com>
Subject: Re: Topband: RF attenuators
To: n4zr at contesting.com, "'TopBand'" <topband at contesting.com>
Date: Wednesday, August 24, 2011, 10:05 AM

On 8/24/2011 3:59 AM, Pete Smith wrote:
> Do you have the capability to measure their response?  If they claim 
> they are essentially flat down to 5 MHz, and they don't fall off a 
> cliff below that, they might be a useful alternative to homebrewing, 
> or certainly to the $30 Mini-Circuits splitter.

I have some measurement capability, but with many other things on my 
plate, hesitate to repeat work that a very capable guy like Jack has 
already done.  Although I haven't seen his data, I would certainly trust 
it, and would expect it to show degraded response and/or isolation 
outside the design range of the product involved, and for lower quality 
el-cheapo consumer products.  One of the key advantages of the 
Mini-Circuits splitters is that they typically offer 20-30dB of 
isolation between outputs within their design range.

No, I would not expect response to fall off a cliff at the lower 
frequency limit in a Mini-Circuit spec, but rather for performance to 
gradually decline at lower frequency.  There are a few Mini-Circuits 
splitters, that for example, should still work on 160M, albeit with 
reduced isolation and/or degraded response. I have a 1x4 that I'm using 
to split my Beverages to two main K3 RX and one Sub RX, and a 1x2 that 
I'm using to split a 6M preamp to main RX and Sub RX. While I could 
split the preamp with a Tee, the splitter provides a lot of isolation, 
which has nearly eliminated the strong birdies I used to hear with both 
RX running when I used a Tee to split the preamp. I found all of my 
splitters at hamfests for a few bucks.

73, Jim K9YC
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