Topband: RF attenuators

[Pete Smith]

I highly recommend the articles by Jack Smith, K8ZOA on the Clifton Labs 
web-site.  One title talks about 6 dB splitters, but there is much more 
test data there, including tests of a TV splitter.  See 
<http://www.cliftonlaboratories.com/6_db_hybrid_combiner.htm> and 
<http://www.cliftonlaboratories.com/Documents/Notes%20on%20Building%20a%20Z10050A.pdf>, 
which deals with the design and construction of a 3 dB hybrid coupler, 
with emphasis on good IMD performance, as well as  low loss and good 
isolation.

73, Pete N4ZR

The World Contest Station Database, updated daily at www.conteststations.com
The Reverse Beacon Network at http://reversebeacon.net, blog at reversebeacon.blogspot.com,
spots at telnet.reversebeacon.net, port 7000



On 8/24/2011 3:04 PM, ZR wrote:
> Ive tested dozens of CATV splitters over 25 or so years and they range from
> falling apart as high as 7-8MHZ and many good to 80 but useless at 160.
> By good I mean at least a 10dB RL (2:1 VSWR) and 20dB isolation.
>
> For the cost of 3 small ferrite cores, some wire and a resistor its
> certainly simple to build much better ones.
>
> Carl
> KM1H
>
>
> ----- Original Message -----
> From: "Bill Wichers"<billw at waveform.net>
> To:<jim at audiosystemsgroup.com>;<topband at contesting.com>; "Hardy Landskov"
> <n7rt at cox.net>
> Sent: Wednesday, August 24, 2011 10:46 AM
> Subject: Re: Topband: RF attenuators
>
>
>> It would be easy to check if an attenuator is resistive or capacitive by
>> checking if it will pass any DC. If the attenuator is all resistive you
>> should be able to measure a low (relatively, i.e. not megohms)
>> resistance between the ports and between the center pin and ground.
>>
>> Regarding the splitters not being useable down low in frequency, I think
>> I have one of their 10-1000MHz 2-way splitters at home that I can test
>> down around 1 and 2 MHz easily enough and post the results.
>>
>>   -Bill
>>
>> [snip]
>>> In general, many VHF/UHF attenuators are built with capacitive
>> dividers
>>> rather than resistive dividers, and are unlikely to be useable at HF
>> and
>>> below.  Conversely, simple resistive attenuators are quite suitable in
>>> the 2 MHz range, provided that they are made with resistors that are
>> not
>>> inductive, whereas their stray L and C would render them useless at
>>> higher frequencies.
>>>
>>> 73, Jim Brown K9YC
>>> _______________________________________________
>>> UR RST IS ... ... ..9 QSB QSB - hw? BK
>> _______________________________________________
>> UR RST IS ... ... ..9 QSB QSB - hw? BK
>>
>>
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> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK
>
>