[Mldxcc] Interstation Interference,

[Jeff Stai]

hi Bill - I didn't notice any RF interference between the stations. I haven't analyzed the log to verify this, but it seems to me we never did have one station on 40 and the other on 15 at the same time.

The bigger problem for me was dealing with AF interference between the stations - for example, the other op screaming into his mike while you are trying to pull out a weak one. The full-ear headphones do help, but not as much as I would like. I'm not sure what to suggest, knowing your station setup - other than perhaps a big red that flashes when you are screaming into the mike...;-)

hi Rick - the reasons stubs are preferred in many situations are:

1. stubs can handle full power for much less cost than an equivalent LC based filter

2. the nulls can be quite deep (30dB or more)

3. insertion loss can be quite low (0.1dB, so I am told *)

4. stubs are much more forgiving of mismatches than filters (personal experience) - filters want a 50+j0 across the band

* According to the ARRL review (by N6BV) March 95 of the Dunestar 600, insertion loss varied between 0.5 and 1.1dB.

Filters do have a certain convenience and switchability that is appealing, which is why I am using them now - between the xcvr and amp, of course. I do have plans to migrate to stubs in the coming months.

cheers! - jeff wk6i


At 09:13 AM 12/8/2005, Richard (Rick) Karlquist (N6RK) wrote:
>I never noticed any self-QRM, but I wasn't
>on 15 meters.
>
>FWIW, it is far more effective to make traps
>with a coil and capacitor than a stub.  A piece
>of coax is a very low Q resonator, and you
>can't choose the effective L/C ratio (it's fixed
>by the 50 ohm impedance.)  You can parallel 2 or
>3 pieces of coax in the stub to help with this to
>some extent.
>
>Also, to keep 40 meters out of 15 meters, a low
>pass filter on the 40 station and a high pass filter
>on the 15 station would make more sense than traps.
>
>Rick N6RK
>
>> -----Original Message-----
>> From: mldxcc-bounces at contesting.com
>> [mailto:mldxcc-bounces at contesting.com]On Behalf Of Bill
>> Sent: Wednesday, December 07, 2005 9:14 PM
>> To: Jeff Stai
>> Cc: Mldxcc at contesting.com
>> Subject: [Mldxcc] Interstation Interference,
>> 
>> 
>> To the folks who have operated here in the last couple months,
>> 
>> Please tell me what you recall about interstation interference. 
>> Just before
>> CQWW SSB I installed stubs to keep 15M out of 40M and 40M out
>> of 15M. Trivial tests suggest meaningful improvement.
>> 
>> I'd like to hear from any/all about how things went wrt interstation
>> interference no matter what bands you were on. Specifics would be
>> great but generalities will be appreciated as well.
>> 
>> Thanks for taking the time to reply,
>> 
>> Bill K6KM
>> 
>> >  
>> >
>> 
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--
Jeff Stai               jds at twistedoak.com
Twisted Oak Winery      http://www.twistedoak.com/