Author Topic: Bencher YA-1 Low Pass Filter  (Read 8300 times)

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KC9TNH

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Bencher YA-1 Low Pass Filter
« on: March 31, 2012, 05:16:46 PM »
Some folks are fortunate to have lots of real-estate for dispersed antenna farms that don't impinge on others' modern devices. Particularly for those in a suburban environment embarking on HF, even just getting an antenna up can be a chore - not selecting one but even the simple mechanics of getting the dang thing up in the air. No such luck here, my 80m dipole runs along one side of the house, typical small-town residential lot. It works great thus far; wish I had the room to duplicate it oriented 90° differently.

Not everyone may be in a similar situation but, if you are, it can be frustrating. Awhile back I embarked on a mission to lower my local noise floor just as much as possible. I'd already applied the ginormous RF choke to the AC line coming out of my wife's O2 machine to help with no RF in the house, especially since I am blessed with a very robust safety ground system - the last thing I want to do is pollute the house wiring. I also located any power supplies that were making noise via the handy old-school portable AM radio, made sure unnecessary wall-warts weren't plugged in, located a flourescent ballast that was headed south, allowed the twist in twisted pair to help out the wireless router, and choked the living **** out of the cheap cable modem from the CATV company. (It is a fact of life that, generally, most consumer-grade electronics are made with MUCH less adherence to specs and/or consideration for spectral interference. The up-side is that as a ham, if you're running run of the mill consumer gear with good station practices, you're on the moral high-ground when it comes time to mitigate a "neighborly" issue.)

I'd already put a Type-31 choke on the RG-6 line for the CATV which got rid of a few wavy lines on the TV when I keyed down with 100w on a very specific 20m freq. But as I was moving eventually to an amplifier in the station, what works at 100w may not work at 1000 & I was determined not to be knocking out someone's dish, opening their garage door, or killing the internet or CATV.

When I picked up the amp, the kind gent parting with it threw in a low-pass filter as part of the deal because he now belonged to that part of the landed gentry in my first sentence & no longer needed it.

The Bencher YA-1 is too simple. There are alot of low-pass filters that get rid of just the kind of offending harmonics that cause these residential RF nuisances, but not many of them work with serious power going through the device - like a kilowatt.  This one does.  Frankly, it looks like it was made in the same basic case as my DL-1500 air-cooled dummy load. There are no in/out on the connections, it's just inserted between your antenna and your final RF output.  If you have a tuner, then insert it between your output and the tuner. What comes out onto the antenna will be that much cleaner.

A friend who's a manager for one of the 40m nets I frequent hardly uses his amp because he knocks himself (or family) off the internet - so why have the amp? That was not to be me.

Over the course of a weekend I went, from 80m to 10m, hammer down with as much power as the amp would safely tune for that band. The internet was up & running, I was sure the neighbors were watching a critical (not to me) basketball game, the wife was watching a favorite show and I had a live-streaming weather radar image going 3-ft away from the amp next to me. From 500 on 10m to the full gallon on 40 and 80.

Nothing. Nada. Nyet. Zip.  I even came downstairs & the bride asked "did you get to check your amp yet?"  :D

So if you are looking to mitigate some annoyances because your emanations are offending some of the consumer krap that's out there, spend the $80-90 and get the Bencher.  There are other good reviews out there, and I'm just a sample of n=1, advice on the internet being worth what you paid for it. This will NOT fix situations where you are simply frying something with RF - hopefully not you, either.  But if you need something that will strip out the harmonics from a ham frequency that is bothering these stupid boxes - because they weren't designed right to begin with - this could be just the ticket. Knowing this now, if I'd borrowed it & returned it I'd still be running out to get one. Truly, pay once, cry once.

Hope this helps at least one person keep some hair attached to their scalp.
:)

p.s. The "why" of the amp is another tale but suffice that I can do the Seychelles CW on 40 watts but that guy isn't going to be any help if things "get western" as they say. A handful of trusted friends inside a 300-mile NVIS circle will and it can be tough to hold a 75m signal in difficult band conditions - many times barefoot just won't get it done.
73

Quietus

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Re: Bencher YA-1 Low Pass Filter
« Reply #1 on: March 31, 2012, 06:26:45 PM »
There is much to digest in the above post.  What's said there, might resonate for some's personal antennas, and not so much for others.
 
What was said above, does resonate for the "prepared Ham."  A fair bit of what I read on this board these days seems to be more of high tech solutions, rather than the old school stuff of prepared-ness with a durned HF radio and how are we going to run it to talk amongst ourselves during bad times.  Comms on demand, without the internet or cell phones as crutches to achieve this goal, might be something for Prepared Hams to look at.
 
Everything we do these days comes down to being a bet on outcome.  Regarding personal emergency communications:  which side of the aisle do you come down on?  Is it down-in-the-dirt Get 'er Done HF with primitive antennas... or is it the latest fusion of radio to computer, with the non-expressed hope that infrastructure to support the more modern radio accessories might still be up when the "prepared ham" viewpoint becomes necessary?
 
Time will tell.
 
Can't say that anybody knows the answer to that.  I think, though, that a Prepared Ham board might be emphasizing the simpler and grosser things regarding  the how-tos of using HF radio to talk in hard times.
« Last Edit: March 31, 2012, 06:32:06 PM by Quietus »

spacecase0

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Re: Bencher YA-1 Low Pass Filter
« Reply #2 on: March 31, 2012, 08:45:48 PM »
on the RF feeding into the wiring issue,
using a balun n your antenna designs keeps RF from feeding back  your feedline back to your radio and into your wiring
RF chokes can help some, but keeping the RF from even getting in in the first place is way better.

KC9TNH

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Re: Bencher YA-1 Low Pass Filter
« Reply #3 on: April 01, 2012, 06:30:33 AM »
on the RF feeding into the wiring issue,
using a balun n your antenna designs keeps RF from feeding back  your feedline back to your radio and into your wiring
RF chokes can help some, but keeping the RF from even getting in in the first place is way better.
Yep. The OCF dipole has a 4:1 current balun on it. When I started the process awhile back looking for noise it was simply to get my receive noise floor squared away. I was amazed to find how much signal is put out by medical equipment. I'm assuming (maybe correctly, maybe not) the wife's O2 machine has an AC powered switching power supply as the pulse can be heard. The big choke on the unit's AC line reducing that noise tells me that the noise was travelling back down the outside of the AC line of that unit. Antenna right outside was picking that up, being an equal-opportunity vacuum.