[MRCA] Gilbert Field Antenna Caution and Warning

Wed Sep 24 14:18:09 EDT 2014

Hi Ray - Checking in from the Left Coast....
You guys are showing us the way!  Seems you have a larger group of more
active Radio Squirrels than we have out here.  We are pretty much dispersed
geographically (harder to target) so get-togethers can be smaller than you
guys can muster.  Speaking from my own observations, seems the west coast
is using equipment averaging about 40 years older than you guys generally
get going.  The MRCG net out here (3985 Kc, Saturday evenings, generally
0300Z) is entirely AM, many WWII sets (ART-13, TCK, TCM, Command Sets, TCS,
GRC-9, BC-610 etc - depending upon conditions) with a few newer T-368's,
GRC-19 etc.  There is another 75 meter Mil HF AM net on Sunday mornings,
again mostly WWII era gear.

We are also starting up a Military HF RATT net on 7087 Kc (Sundays at
0230Z) , the former locale of the original "Clatternet".  We have had about
8 weekly nets so far with a mix of mechanical machines and riceboxes (with
fldigi RATT) systems as guys re-locate, drag out and fire up the mechanical
GRC-46, M15 and M19 sets.  John's GRC-46 complete RATT set "prints" great!
Seems to have a small but growing following so far.  We worked a guy in
Arkansas on the Net so there is some hope for a Right-Left Coast
connection....I'm using a PRC-47 / CV-2455 RATT converter but an old DOS
laptop glass terminal since I don't have a proper mechanical machine...

We have an annual rally at Camp San Luis Obispo on the central California
coast in May, some pix here:
http://www.n6cc.com/west-coast-military-radio-collectors-group

We run some field ops there, again mostly WWII gear with PRC-6's and 25's
as well, plus some HFCW on occasion.  The MRCG also runs a dedicated
Military Field Day in either August or November and it is pretty popular,
based at the coastal defense site at Ft. MacArthur in San Pedro.  Again, a
lot of AM but also Halftrack/command car ops on WWII FM sets.  Dennis,
W7QHO has a number of nice Youtube clips of those events.

We also have a small showing at the annual Military Vehicle Collectors of
California rally's in April and Sept every year.  Usually 200+ mil vehicles
in attendance, some with functioning radios as well.  Driving a Deuce or
Command Car from LA or Portland takes real dedication..  We set up a small
CP at the camp and it is a lot of fun with the MRCG net on 3985 AM Saturday
and HF CW during the days...some pix here:
http://www.n6cc.com/battalion-communications-center

There are a few VHF AM sets at these events, notably MAW, ARC Type 12,
ARC-1, SCR-522 etc.  So far no URC-4's that I am aware of.  Our PRITAC freq
is 144.450 and that usually gets clobbered by the #*^@%$ APRS repeaters on
144.390 Mc.  Oh Well, enemy jamming....  FM nets run on 51.0 Mc...

There is also a Military Radio Collectors Net on 3996 Kc USB Wednesday
evenings (0300Z I think) and those often have a PRC-47 or two but it seems
more of the newer gear like you guys use.  They are pretty active; I have
not checked in recently...

It's all good.....MRCG-ers:  What did I miss or misrepresent?
73
BT
N6CC sends
NNNN

On Wed, Sep 24, 2014 at 5:49 AM, Ray Fantini <RAFANTINI at salisbury.edu>
wrote:

> Almost everything built for military or commercial service in the last
> thirty years has adequate protection for operation in high RF fields,
> considering much of the equipment is expected to operate in a radio crowded
> environment. Most of the cheap Ham or bottom end commercial stuff has
> issues with overload and images, just think back to the garbage that Wilson
> produced in handhelds back in the eighties.  All of the General Dynamics
> family of R-1051 and the RT-618 transceivers have relays installed in the
> front ends with fast acting RF sense circuts to protect the front end in
> the event of a transmitter too close.
> All that being said still some common sense is required, if for nothing
> else then it gets hard to copy SSB when your too close to the other
> station. At Gilbert the net control for Fridays net, a PRC-47 was just
> about a mile away from me at Beltsville State Park and when they came up it
> was plenty loud on my Sunair. Think it may have been testing the limits of
> its AGC action. The Harris 5020 a tough little radio and would assume that
> in the design criteria it's expected that they will operate in close
> proximity at times but don't think I would try it myself with what the
> radio cost.
> I also have to say that with the three or so PRC-47 transceivers in
> operation in the net I was impressed with the ability of net control to be
> heard by everyone and hear everyone with no issues using just the antenna
> mounted on the radio and a four wire counter pose. Good showing for those
> old radios.
> So it was a good show for operation of Vietnam to newer family of SSB
> radios and an opportunity to set up and operate in the field in a real
> world example of their use. We also had much 144.25 URC-4 activity, maybe
> the largest collection of working URC-4 transceivers in one place at one
> time for the last twenty years? Dayton has the title of the largest
> collection of working BC-611 3885 AM transceivers at one location all in
> working condition for the WW2 net but think MRCA at Gilbert is now maybe
> largest field exercise for 60 meter SSB and primitive AM on 144.25 although
> will admit that I used a URC-110 for 2 meter AM. Dayton at least in my
> experience still keeps the record for most active backpack and handheld
> stations for its Cold War Net on 51.0, always around twenty to thirty
> people and the WW2 net on 3885.
> Would wonder what the people out on the left coast are doing on there get
> together and if they are running field exercises too?
>
>
> Ray F/KA3EKH
>
> -----Original Message-----
> From: MRCA [mailto:mrca-bounces at mailman.qth.net] On Behalf Of Peter
> Gottlieb
> Sent: Tuesday, September 23, 2014 10:59 PM
> To: mrca at mailman.qth.net
> Subject: Re: [MRCA] Gilbert Field Antenna Caution and Warning
>
> I would hope (!) those newer radios, which cost an astronomical amount,
> would have effective protection.
>
> My old Harris RF-590A has a relay in the front end which isolates the
> receiver from the antenna at a certain level on the antenna (I've reached
> that a number of times when I had multiple antennas up and there was enough
> coupling).
>
> Would they have reduced the protection for newer radios?
>
>
>
>
> On 9/23/2014 10:46 PM, WA5CAB--- via MRCA wrote:
> > Anything new enough to have to worry about co-location problems is
> > also new enough to bring the owner/operator to the attention of the
> > modern day Gestapo.  And too new to be discussing here.  Avoid it and
> > you won't have either problem.
> >
> > Robert Downs - Houston
> > wa5cab dot com (Web Store)
> > MVPA 9480
> >
> > In a message dated 09/23/2014 17:13:23 PM Central Daylight Time,
> > w2hx at w2hx.com
> > writes:
> >> Hi Breck, et. al. That was me! My Harris RF-5020 gives S meter
> >> readings and it read S9+90.  You are, of course, correct about close
> >> co-location of transmitters. My hunch is, after a certain generation of
> radios, the "newer"
> >> ones had very good protection in the front ends. After all, in a
> >> combat environment, you can't exactly tell the other guy to move
> further away, hihi.
> >> In my Harris, it has very stout PIN diodes to protect the front end.
> >> I can do some math, but based on 65V worth of pin diode protection,
> >> that is something like 80W directly injected into the receiver.  I
> wouldn't try it, however.
> >> But your point is well taken. Some of the radios we use are likely
> >> not to have such good protection (or any for that matter)!
> >>
> >> 73 Eugene W2HX
> >>
> ______________________________________________________________
> MRCA mailing list
> Home: http://mailman.qth.net/mailman/listinfo/mrca
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:MRCA at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/mrca/attachments/20140924/85fcbf07/attachment-0001.html>