[ARC5] Powering ARC5/SCR274 sets
Tom Bridgers
tarheel6 at msn.com
Thu Jul 23 23:22:19 EDT 2015
Thought the ARC-5 List members would enjoy reading
about W6DJX, Hank Brown's experiences with operating
the SCR-274 sets portable.
From: htbrown at earthlink.net
To: tarheel6 at msn.com
Subject: Re: Powering ARC5/SCR274 sets
Date: Wed, 22 Jul 2015 13:10:47 -0700
Hank's message: I Use 2 Twelve Volt WalMart Batteries to power the TXYes, I
have one SCR-274 set that I use for field operation. The set has one
transmitter and receiver plus the control box and TX supply/modulator. The
set is mounted in a wood rack configuration and has heavy cables with battery
type clips to connect to a 28 V supply. I have good operation with two 12
V car batteries (Wal-Mart about $35 each) with a heavy short jumper to put them
in series. The batteries are both charged on the bench before an event and used
in the truck or the car with the rig. I do not use the car to feed the batteries
and usually get several hours of operation. Rx's are powered by SS power supplies.To improve operation a bit I use
solid state supplies for the receivers which are PP-2792/ARN-30D or Dynaverter
DV-10A. They were designed to fit on the receiver as the original dynamotors.
The units are quieter than dynamotors and also use less input for the same
output. Electrical noise is also down compared to the dynamotors. Conserving Battery Power for the TX.I use the
regular TX dynamotor configured as original. During the event I leave the
receiver on but only turn on the TX when ready for use. If you are running phone
you can leave the TX on to keep the filaments hot and the dynamotor off unless
PTT is pushed. If the event is on CW you can leave the TX on and switch to CW
only when ready to transmit. This saves some input power since the
dynamotor runs all the time when in CW mode. Antenna Info, Loading it Up, and Important Ground Info.I usually use a 25 to 30 foot wire
on a fiber glass pole with sections up to about 30 or 35 feet or so. The wire
feeds the set thru the antenna meter as in the original. Now, I found that
a ground connection to the car helps so I have a wire with a clip in the truck
for that purpose. I also drive a ground rod down a couple of feet and
attach that to the rig. However, depending on the location, the ground rod may
or may not provide a good ground. What I do next is carry a couple gallon jugs
with water to pour around the ground. Let it sink in and add some more
water before the event. This helps quite a bit. So basic operation is as
original and seems to work pretty good. Operating the SCR and ARC-5 radios at home.I might
add that my main home station uses SCR or ARC transmitters with AC supplies in
original racks. I can run up to 40-50 watts output on CW or phone and use a
short piece of RG-58 across the output link to a Harvey Wells SO match antenna
tuner. This will match just about anything and does a good job while
keeping the gear in original status. I change transmitters in the rack to
go from 80 to 40 meters. A home brew PP 6L6 modulator is used for phone. Hope
this helps a bit and if you have any questions give me another buzz. 73 de
Hank W6DJX
----- Original Message -----
From:
Tom Bridgers
To: Henry ARC-5 Brown
Sent: Sunday, July 19, 2015 7:32 AM
Subject: Powering ARC5/SCR274 sets
Good morning Henry,
Was wondering if you'd be willing to
contribute your experiences with operating your ARC5/SCR274 radios from
battery power....?
I remember that you did so quite successfully, but I don't recall
the fine points. For example, leaving the TX dyno off when not transmitting,
running the car and letting the car's alternator charge up one battery,
etc.
One person said he used 2 series connected 10 amp twelve volt
battery chargers to keep the battery voltage from slumping.
And so on.
Hope you're doing well.
Best,
Tim KE4RHH
---------- Forwarded message ----------
From:
arc5-request at mailman.qth.net
Date: Jul 19, 2015 9:17 AM
Subject: ARC5
Digest, Vol 138, Issue 11
To: arc5 at mailman.qth.net
Cc:
Send ARC5 mailing list submissions
to
arc5 at mailman.qth.net
To subscribe or unsubscribe via the World Wide
Web, visit
http://mailman.qth.net/mailman/listinfo/arc5
or,
via email, send a message with subject or body 'help'
to
arc5-request at mailman.qth.net
You can reach the person managing the
list at
arc5-owner at mailman.qth.net
When replying, please edit your Subject
line so it is more specific
than "Re: Contents of ARC5
digest..."
Today's Topics:
1. Re: SCR274
field test (WA5CAB--- via ARC5)
2. Re: SCR274 field test
(aj1g at comcast.net)
3. Re: SCR274 field test (Bill
Cromwell)
4. 4010 kHz in 8th Naval District MARS...1967
(Mike
Morrow)
----------------------------------------------------------------------
Message:
1
Date: Sun, 19 Jul 2015 01:34:12 -0400
From: WA5CAB--- via ARC5
<arc5 at mailman.qth.net>
To: arc5 at mailman.qth.net
Subject: Re:
[ARC5] SCR274 field test
Message-ID:
<37c75.385bce86.42dc90d4 at cs.com>
Content-Type: text/plain;
charset="UTF-8"
What dynamotors are you using? There was a 14
volt dynamotor made for the
receivers (DY-1/ARR-2 and a Navy equivalent
for the RAT or R-148)) but never
one for the transmitters. For a
14 volt system you should be using at
least #10 AWG wire and a
solid ground to the vehicle on whatever dynamotor
supply you are
using. And don't try to run the transmitters without the engine
running.
Before I went to Vietnam in 1967, I had a
4-transmitter 8-receiver
installation in my International Scout 80 and
could reliably work into central and
western Oklahoma on 4010 KC from up
the hill near my parents home in north
central Louisiana. The
Scout had a 14/28 VDC system installed, though, with a
second 14 V
generator piggy-backed on the first. The radios were all box
stock. Antenna was a commercial center-loaded whip but I can't
recall the
brand name.
FYI, starting current for a typical shunt
or compound wound dynamotor is
about 3X the FLA. So for the 9 A
you reported earlier, around 27-28 A. Far
from huge.
Robert
Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480
In a
message dated 07/18/2015 22:34:18 PM Central Daylight Time,
arc5 at mailman.qth.net writes:
> Yes the startup current is huge, I
was aware of that, but the drop is
> after it's already running in
standby under transmit load. (the dyno runs
> continuously in CW
mode). The startup inrush current will pop a 20A fuse, but
> not a
30.
>
> I made the voltage measurements right at the battery
terminals with key
> down. The power cable is about 6 feet of #12
AWG. The drop is nominal and
> there is no noticeable warmth, yet the
transmitter can pull down the battery
> voltage quite dramatically.
>
>
> On Saturday, July
18, 2015 10:04 PM, Roy Morgan <k1lky68 at gmail.com>
>
wrote:
>
>
>
> On Jul 18, 2015,
at 8:28 PM, J Mcvey via ARC5 <arc5 at mailman.qth.net>
>
wrote:
>
> >...how can 16.5 amps draw a 130AH battery down
to 11v from it's fully
> charged resting voltage of 12.6v ? ( it
recovers on key up)
>
> Note well where you are measuring the
voltage. There may well be IR drop
> in the leads from your
battery to the radio - if you are measuring the
> voltage at the
radio, I?d bet on it. And especially so if you are getting the
> radio supply voltage from somewhere other than the battery terminal
itself.
>
> If the wire to the radio does not come off the
battery itself (and the
> connectors are bright and shiny inside)
you?ll have voltage drop in the
> vehicle harness.
>
>
Roy]
>
> Roy Morgan
> k1lky68 at gmail.com
> K1LKY
Since 1958
------------------------------
Message:
2
Date: Sun, 19 Jul 2015 12:10:50 +0000 (UTC)
From:
aj1g at comcast.net
To: J Mcvey <ac2eu at yahoo.com>
Cc: ARC-5 List
<ARC5 at mailman.qth.net>, Roy Morgan
<k1lky68 at gmail.com>
Subject: Re: [ARC5] SCR274 field
test
Message-ID:
<1619639166.20190359.1437307850132.JavaMail.zimbra at comcast.net>
Content-Type:
text/plain; charset=utf-8
I have not heard it stated yet, but are you
running the engine in the vehicle while running the radios? I have been
running command sets and TCS sets, GRC-9s , and WS-19s from either 12 V or
series up 24 volt batteries (depending on the set's power requirements) both
in the shack floated across the outputs of DC power supplies, or in vehicles
(specifically the GRC-9) with the engine running to keep the battery
charged, and never have had a problem with sucking down a battery as long as
I was using a power source that could make up for the steady state current
draw of the radio, and the battery will easily handle the starting draw of
the dynos. But if you are trying to run a command set system or any dyno
powered radio directly off of a battery, it of course will suck down the
battery voltage pretty quickly. You will obviously get more run time from a
deep cycle marine type battery than a typical vehicle starting type battery
but don't expect to run them the set very long.
I have run the GRC-9
in the field for several hours off of a fully charged deep cycle marine
battery as long as I switched off the transmitter dyno while receiving. In
the shack, the WS-19, GRC-9 and TCS sets are run from a deep cycle marine
battery that is floated across the output of two now very old Sears 12V 10 A
max current chargers run in parallel, which keep up with the steady state
draw just fine for extended periods. If you are trying to run your command
set system off of just a battery, switch off the transmitter dyno unless you
are actually transmitting. It's your biggest load by far, and all you are
doing bu leaving it running is sucking down the battery during receive
periods. The net current draw of that dyno idling in receive is way less
than the very brief starting surges when you need to power it up to
transmit.
The voltages you quoted for key up/key down below sound
low, even for a fully charged battery supplying the set without the vehicle
alternator keeping a charge on the battery. A normal fully charged 12V
battery should be a bit higher (I just measured my shack 24-28V bus series
up deep cycle marine batteries at 13.3/13.4 volts each at full charge. The
under load voltage drop at the batteries with the bus PP7333 60A DC power
supply off is very little initially, even under the load of of my T-195
which draws way more current than my command sets that also run on the same
bus. Your battery may have one or more weak cells. I actually have run the
command set system for several hours (during Hurricane Sandy) off the 24-28V
DC bus in a battery only lineup with the transmit dyno off while receiving.
With your vehicle running and the alternator charging the battery
normally, you should see around 13.6 volts at the battery terminals
regardless of whether the radio is running or not. If you are only seeing
12.6 volts under load with the battery being charged by the alternator, you
may have a bad cell in the battery that is holding the voltage down, or the
alternator output is low for some reason.
I run No. 10 stranded
about 6 feet (for both the positive and negative leads) directly to the
battery terminals in the Tacoma to run the GRC-9powered by its DY-88 power
supply, The voltage drop at the radio end of the terminals under load of
that set is minimal. Battery terminal voltage with the engine running is
about 13.8V under load. I have 30 amp fast blow fuses in both the negative
and positive leads at the battery and have never popped one on the GRC-9
DY-88 transmitter dyno start ups.
Good luck..keep at it you will get
it going eventually! I have the parts that I could make up a command set
mobile system from to run on 12 volts, using either a TCS D401 12V/440V
dyno, or a PE101 BC-645 IFF set dyno that someone had apparently previously
used in a mobile setup. All I need is the time to put it together. Larry,
NE1S, runs a nice command set mobile setup in his vintage Ford Falcon.
73 de Chris AJ1G Stonington, CT.
----- Original Message
-----
From: "J Mcvey via ARC5" <arc5 at mailman.qth.net>
To:
"Roy Morgan" <k1lky68 at gmail.com>
Cc: "ARC-5 List"
<ARC5 at mailman.qth.net>
Sent: Saturday, July 18, 2015 11:30:25 PM
Subject: Re: [ARC5] SCR274 field test
Yes the startup current is
huge, I was aware of that, but the drop is after it's already running in
standby under transmit load. (the dyno runs continuously in CW mode). The
startup inrush current will pop a 20A fuse, but not a 30.
I made the
voltage measurements right at the battery terminals with key down. The power
cable is about 6 feet of #12 AWG. The drop is nominal and there is no
noticeable warmth, yet the transmitter can pull down the battery voltage
quite dramatically.
On Saturday, July 18, 2015 10:04 PM, Roy
Morgan <k1lky68 at gmail.com> wrote:
On Jul 18, 2015, at
8:28 PM, J Mcvey via ARC5 <arc5 at mailman.qth.net> wrote:
>
...how can 16.5 amps draw a 130AH battery down to 11v from it's fully
charged resting voltage of 12.6v ? ( it recovers on key up)
Note
well where you are measuring the voltage. There may well be IR drop in the
leads from your battery to the radio - if you are measuring the voltage at
the radio, I?d bet on it. And especially so if you are getting the radio
supply voltage from somewhere other than the battery terminal itself.
If the wire to the radio does not come off the battery itself (and
the connectors are bright and shiny inside) you?ll have voltage drop in the
vehicle harness.
Roy]
Roy Morgan
k1lky68 at gmail.com
K1LKY Since 1958
______________________________________________________________
ARC5 mailing list
Home: http://mailman.qth.net/mailman/listinfo/arc5
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:ARC5 at mailman.qth.net
This list hosted by: http://www.qsl.net
Please help support
this email list: http://www.qsl.net/donate.html
------------------------------
Message: 3
Date:
Sun, 19 Jul 2015 09:00:17 -0400
From: Bill Cromwell
<wrcromwell at gmail.com>
To: arc5 at mailman.qth.net
Subject: Re:
[ARC5] SCR274 field test
Message-ID:
<55AB9F61.9050200 at gmail.com>
Content-Type: text/plain;
charset=utf-8; format=flowed
Hi J,
You have answered the
question about where your measurements were taken
and the wire gauge to
the dynamotors. You haven't said anything about
the engine running or
not. Try measuring the battery terminal voltage
while you are cranking
the engine. V-8 engines can drop that to 8 or 9
volts! Those batteries
have internal resistance that changes with the
state of the charge
(higher internal resistance when discharged).
Your cranking battery
is designed for those high surge currents like
starting the engine. But
it won't tolerate being deeply discharged at
all. How old, what
condition, and what charge state was that battery?
How do you
know?
Deep cycle batteries have traded the high surge current
capability for
the 'deep discharge cycle' capability. They have a higher
internal
resistance (which gets higher as the battery discharges). You
can expect
a lower terminal voltage with a higher current draw,
especially with
high surge currents. What was the age, condition, and
charge state of
that battery when you tested it? How do you
know?
The 'how do you know' questions have their answers in
measurements of
the specific gravity of the electrolyte and load tests
to compare them
to manufacturer's specifications. Sulphated and
contaminated plates will
reduce the energy available. So will *any*
corrosion in the terminals
(between the posts and
connector).
Good luck with your project. I hope the solution to your
problems is
resolved by starting the
engine.
73,
Bill
On 07/18/2015 08:28 PM, J
Mcvey via ARC5 wrote:
> I was hoping that I could run the dual rx/tx
setup off of my jeep battery, but it seems it needs a stiffer deep
cycle type to keep up with the load in transmit. The jeep batter sagged
badly and for that matter so did the deep cycle battery (11v under full
load), but it was sufficient to keep things working.
> I think i'm
missing something about the nature of dynamotors and batteries ...
>
With the two transmitter filaments ( 4X 1625) @ 2a and the rx pulling about
2.5a, that's a constant 4.5a, add the dyno in stanby which bring the the
total cw break-in receive mode 7.5a.
> The dyno says 9a @ 12V
continuous duty for 440v @ 200 ma .That should be a max of 16.5a a key down.
So how can 16.5 amps draw a 130AH battery down to 11v from it's fully
charged resting voltage of 12.6v ? ( it recovers on key up)
> When I
was using a SMPS, it sounded good, now I've got some chirp due to power
droop.What say you experts?
> BTW, I was doing this in "original spec"
using a very short wire antenna of about 35 feet on 80 meters in NVIS
config. Loads right up at about 50% inductance with coupling also about 50%.
I like to stick a NE-2 ( leads shorted together) in the antenna clip on the
bc-442 to see how bright I can make it glow. It tracks well with antenna
current.
>
------------------------------
Message:
4
Date: Sun, 19 Jul 2015 09:17:12 -0400 (EDT)
From: Mike Morrow
<kk5f at earthlink.net>
To: arc5 at mailman.qth.net
Subject: [ARC5]
4010 kHz in 8th Naval District
MARS...1967
Message-ID:
<6519930.1437311833216.JavaMail.root at elwamui-lapwing.atl.sa.earthlink.net>
Content-Type: text/plain; charset=UTF-8
Robert
wrote:
>Before I went to Vietnam in 1967, I had a 4-transmitter
8-receiver
>installed in an International Scout 80 and could reliably
work into central and
>western Oklahoma on 4010 KC from up the hill
near my parents home in north
>central Louisiana. The Scout had
a 14/28 VDC system installed, though, with a
>second 14 V generator
piggy-backed on the first. The radios were all box
>stock. Antenna was a commercial center-loaded whip but I can't
recall the
>brand name.
Robert...now that's an amazing array
of command set gear. I'd love to know a lot more details. Did
you use the original racks and modulator and control boxes, and was it all
AN/ARC-5 or all SCR-274-N? You must have procured most or all of the
gear on your own dime...for although the MARS equipment issue program wss
going strong then, the USN/USMC MARS didn't have a lot of command set gear
in the mid-1960s. Plus...unlike the Army and USAF MARS, equipment
accountability was maintained by the USN. It wasn't dropped on my
issued AN/SRR-13A and AN/ARR-15 until the mid-1970s.
You must have
used CW on 4010 kHz since USN MARS normally used LSB there. After 1967
I spent many hours each week on 4010 kHz in Arkansas during my late high
school years as N0LTD. I also spent a lot of time on the district
frequency of 7375 kHz on CW and LSB nets. I'll bet one of your
transmitters was on 7375 kHz...do you remember station NAV8? What was
your call?
Your command set receivers must have been a bit of
challenge for use on these LSB frequencies. In the late 1960s, in
Arkansas only Army MARS still had an AM net, a little below 3500
kHz.
My principal use of command set gear back then was copying
maritime Morse between 400 and 510 kHz on a BC-453-B (which I still
have). I'm sure I'm not the only one here who would enjoy reading more
details of your command set mega-installation and its use on MARS and
80/40m.
Mike /
KK5F
------------------------------
Subject: Digest
Footer
_______________________________________________
ARC5
mailing list
ARC5 at mailman.qth.net
http://mailman.qth.net/mailman/listinfo/arc5
------------------------------
End
of ARC5 Digest, Vol 138, Issue
11
*************************************
More information about the ARC5
mailing list