Topband: RF attenuators

[Jim Brown]

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