[Rover] Interstation Interference in Multi-Op Rovers

Tue Sep 26 23:03:51 EDT 2017

Hi Robin,

2m is the major concern. We get a little interference on 432 from 6m, but I
think a 2m notch on the 6 station should cut out the harmonics QRMing 432
as well. I don't recall any issues with 222. I think 2, 2' sections would
probably work, one for an unterminated 2m notch on the 6 station and one
for a terminated 2m bandpass on the 2 station. I probably could go
overboard here and make them for other bands, but the 2 sections would
cover our main big issues and I don't want to take advantage of your
generosity.

Thanks again, my ULS address is valid and I can work with whatever way
you'd like to receive the money. Just let me know what it costs to ship and
I'll get it over to you.

73,
Sean WA1TE

On Tue, Sep 26, 2017 at 1:15 PM Robin Midgett <K4IDC at comcast.net> wrote:

> What length do you require, and how many of that length?
> Working with the 3/4" CATV line is easy; a SO-239 barrel connector will fit
> easily once you hollow out the dielectric foam. Use a hose clamp to connect
> the shield to the barrel.
> http://amfone.net/Amforum/index.php?topic=29007.0;wap2, or Google "CATV
> line ham radio"
>
> You cover shipping, cable is free.
>
> On Mon, Sep 25, 2017 at 10:58 PM, Sean Waite <waisean at gmail.com> wrote:
>
> > Hi Robin,
> >
> > That would be great! It sounds like the 3/4 inch stuff works well for
> > stubs. I don't really have a concept of how big the stuff is, the
> heaviest
> > cable I've used so far is LMR-400. I'd appreciate it if we could get a
> > little extra so that I can practice making connectors for it, it doesn't
> > appear to be too difficult but sometimes "ham" applies to my fists as
> well
> > as my hobby.
> >
> > Would you want anything for the cable or for shipping?
> >
> > Thanks and 73,
> > Sean
> >
> > On Fri, Sep 22, 2017 at 2:47 PM Robin Midgett <K4IDC at comcast.net> wrote:
> >
> > > I have scads of CATV hard line. I'm happy to cut a section & send it to
> > > you. 1/2", 3/4" & 1" diameters.
> > >
> > > On Fri, Sep 22, 2017 at 1:38 PM, Sean Waite <waisean at gmail.com> wrote:
> > >
> > > > Hi Jonesy,
> > > >
> > > > I don't know why my brain stuck on blocking the 6m signal at the 2m
> > > radio.
> > > > It makes much more sense to do block the ~150MHz harmonic at the 6m
> > > radio.
> > > > Any idea how much difference a lower Q piece of coax - either thinner
> > > > heliax or something like LMR400 - would change the results? I gather
> it
> > > > makes them a little more broadband, but I don't know for sure. CATV
> > cable
> > > > is great but can be a little hard to get a hold of.
> > > >
> > > > We were getting some minor interference on  432 as well. I might have
> > to
> > > > look into a stub there as well.
> > > >
> > > > Thanks,
> > > > Sean WA1TE
> > > >
> > > > On Thu, Sep 21, 2017 at 9:21 PM Jonesy W3DHJ <mailserver at jonz.net>
> > > wrote:
> > > >
> > > > > On Thu, 21 Sep 2017, Sean Waite wrote:
> > > > >
> > > > > >Thanks, I suspected it might be something like that. We get some
> > > lighter
> > > > > >interference on 70cn as well, which is a few more harmonics up.
> > > > > >
> > > > > >My worry with the coax notch filters is bandwidth - 150MHz is
> pretty
> > > > close
> > > > > >to 2m. I suppose using higher quality coax/heliax and tuning to
> > 51MHz
> > > > > would
> > > > > >help with that.
> > > > > >
> > > > > >The rigidity of heliax might make it rough in the rover, a 5' long
> > > chunk
> > > > > is
> > > > > >going to be interesting g to manage and will likely go somewhere
> > > outside
> > > > > >the car on the ground.
> > > > >
> > > > > Use 3/4" cable TV "hardline" -- use it as a 144.2 mcs suck-out trap
> > on
> > > > > the 6M rig -- an open 1/4 wave at ~~15" or a shorted 1/2 wave at
> > ~~32".
> > > > >
> > > > >                 https://w3dhj.net/catvhardline.html
> > > > >
> > > > > If you try to trap the 6M rig (50.130 mcs) at the 2M rig, you run
> > into
> > > > > the problem of the 6M trap working just as nicely at 150.39 mcs --
> > > which
> > > > > may be too close, Q-wise, for the 2M rig.
> > > > >
> > > > > Another issue - besides just "interference" - is the possibility of
> > > > > blowing out the front end of the 2M receiver with simply the
> > > > > overpowering by the 6M rig.  I blew out a 2M GasFET preamp because
> > > > > my 6M halo is mounted between my stacked pair of 2M halos.
> > > > > Sigh...  I just do without that GasFET preamp now.
> > > > > I can certainly hear anyone that can hear me!  HI!HI!
> > > > >
> > > > > Jonesy
> > > > > --
> > > > >   Marvin L Jones     | W3DHJ      | W3DHJ  | https://W3DHJ.net/
> > > > >    Pueblo, Colorado  |  @         | Jonesy |     __
> > > > >     38.238N 104.547W |   jonz.net | DM78rf | 73  SK
> > > > >
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