[CQ-Contest] SO2R technical questions

Wed Jan 21 07:40:13 EST 2015

Or this 
<http://www.pvrc.org/~n4zr/Articles/Simple%20Protection%20for%20the%20Fledgling%20SO2R%20Station.pdf>. 
I developed it with advice from W2VJN.  Lit it up plenty of times 
learning my way around SO2R. Cost less than $5

73, Pete N4ZR
Check out the Reverse Beacon Network at
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blog at reversebeacon.blogspot.com.
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On 1/20/2015 11:41 PM, Jeff Blaine wrote:
> Putting some sort of front end protection on the rig when working out 
> the coupling and isolation issues is a great idea.  I've never fried 
> anything in the last 6 years of So2r fooling about.
>
> However, it can happen.  A couple of weeks back I literally got my 
> wires crossed when running a test on a rig and ended up dumping 100W 
> into my main station rig.  Fortunately replacing the ailing board was 
> not difficult but it was expensive.
>
> Assuming your rig has facilities for a RX antenna, something like this 
> is really cheap insurance...
>
> http://www.dxengineering.com/parts/dxe-rg-5000
>
> 73/jeff/ac0c
> www.ac0c.com
> alpha-charlie-zero-charlie
>
> -----Original Message----- From: Jeff Blaine
> Sent: Tuesday, January 20, 2015 7:07 PM
> To: Mike & Coreen Smith VE9AA ; cq-contest at contesting.com
> Subject: Re: [CQ-Contest] SO2R technical questions
>
> Mike,
>
> I want to caution you on one point.  From a receiver frying 
> standpoint, the
> use of the amp is not at all the threat magnifier that you would think it
> is.  It's very easy to fry rigs with "only 100W."  100->1500 is around 13
> dB.  So 100W is around 50 dBm, and 1500W is around 63 dBm.  To put 
> that in
> perspective, a good rule of thumb is that you don't want the 2nd rig 
> to ever
> see anything over 0 dBm.  By point is not to diminish the 13 db, but 
> rather
> to illustrate that even with 100W, getting to "safe" is not a trivial
> exercise.
>
> Get VJN's book and focus on the isolation.  The shack side gear for
> switching, etc, will be steered more by the mode you run and how much 
> of an
> automatic life you want.  Those are all convenience things - isolation is
> about first keeping the 2nd rig from getting blasted away by the 
> first, and
> secondly, about suppressing the harmonic and desense caused by one rig to
> the other - so that you can actually do some work on the 2nd rig when the
> first is transmitting.
>
> Good luck!
>
> 73/jeff/ac0c
> www.ac0c.com
> alpha-charlie-zero-charlie
>
> -----Original Message----- From: Mike & Coreen Smith VE9AA
> Sent: Tuesday, January 20, 2015 5:52 PM
> To: cq-contest at contesting.com
> Subject: Re: [CQ-Contest] SO2R technical questions
>
> Just occurred to me that I had both preamps engaged in radio 2 which 
> is an
> IC746.  It's S-meter seems overly generous anyways.  Looks like 2nd 
> and 3rd
> harmonics are more like S9+10dB with no preamps on. (only time I would 
> need
> them would be maybe on a quiet 10m band to pull out super weak 
> signals).the
> initial "spike" is higher, which I think is a function of the Icom 
> digital S
> meters which I really don't like.
>
>
>
> So, at constant S9+10dB readings (initial spike higher).solid dashes @ 
> 30wpm
> CW.am I safe?
>
>
>
> Is there a better way to measure?  FM mode?  Readings with a scope of 
> some
> kind or ?
>
>
>
> Thanks
>
>
>
> Mike VE9AA
>
>
>
> Mike, Coreen & Corey
>
> Keswick Ridge, NB
>
>
>
> From: Mike & Coreen Smith VE9AA [mailto:ve9aa at nbnet.nb.ca]
> Sent: January 20, 2015 5:40 PM
> To: 'cq-contest at contesting.com'
> Subject: SO2R technical questions
>
>
>
> How can I tell if I have too much energy at the input of "radio 2" when
> transmitting on "radio 1" ?
>
>
>
> I've done a few DXpeditions  and field days (CY0AA, CY9AA etc.) and we 
> had
> some cheapie bandpass filters and some rapidly made crappy coax stubs
> (without using any kind of device other than a calculator and a measuring
> tape to verify the correct lengths).
>
> At times we  operated w/o one or both (both LP and QRO) and sure, we had
> interference, but nobody blew up a rig.
>
>
>
> Now nearly 2 decades later I am just barely dipping my toe into the SO2R
> waters so with N1MM+'s help, today hooked up my Winkey to 2 rigs 
> (IC7410 &
> 746) and when transmitting on a wide variety of antennas on radio one
> (HF9V, A3S, Inverted L's for 80/160), and limiting radio 2 to only a 
> ZS6BKW
> as an inverted Vee (G5RV like) antenna about 50-60' away from all the
> various antennas, harmonics were fair to bad, but not what I would call
> severe. (no stubs, no BPF's, nuttin' but air).
>
>
>
> CW peaks looked like around *50-60/S9 and steady dits were *40/9 if those
> cheezie Icom bar-graph S-meters are to be believed. *(if I was on the 
> exact
> 2nd or 3rd harmonic frequency)
>
>
>
> Is this too much signal?
>
>
>
> I can build some coax stubs over time...and I am working on a YCCC 
> SO2R box
> as time permits but don't have a lot of spare dough for BPF's (2 of them
> would run me $1200-$1400 CDN by the time I had them in the shack)
>
> nor a SIX-PAK(another $1k_), thus I am wondering about cutting costs 
> going
> in.  Another local tried SO2R, didn't like it and had spent many 
> thousands.
> I don't have the spare dosh, nor will I, hence my question..
>
>
>
> If I am willing to leave the amp turned off (sigh..), and antennas 
> will all
> be separated only 50', how do I know if I have too much signal at the 
> input
> of the 'other' radio?
>
>
>
> Oh and feel free to school me on SO2R...I have nearly googled the 
> internet
> dry, so have done lots of reading, so if you have a web page up, I've 
> likely
> seen it ;-)  Just never tried it.
>
>
>
> Technique is what I lack.
>
>
>
> I figured it was time.  I find myself (especially in CW contests) 
> calling CQ
> and ALT-TABBING over to check my email, surf the net, watch the greyline
> maps, stare out the window , talking to family etc. a LOT in contests.
>
>
>
> Is SO2R the next step?
>
>
>
> Mike VE9AA
>
> p.s.- I will sorely miss using the amp, but if I try SO2R @ 100w and like
> it, maybe I can stumble onto some cheap 419 BPF's and a 6-pack somewhere
> later on.  I don't care a hoot about automation.  I like to flick the
> switches manually.
>
>
>
> Mike, Coreen & Corey
>
> Keswick Ridge, NB
>
>
>
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