[ARC5] Bear ''raslin', or, "The ATC and Me" (Very Long)
Francesco Ledda
frledda at verizon.net
Sun Jul 4 18:07:00 EDT 2010
The same thing happened when I powered my T-195 for the first time. It
scared the hell out of me...
-----Original Message-----
From: arc5-bounces at mailman.qth.net [mailto:arc5-bounces at mailman.qth.net] On
Behalf Of jcoward5452 at aol.com
Sent: Sunday, July 04, 2010 5:00 PM
To: kgordon2006 at verizon.net; arc5 at mailman.qth.net; arc5 at ix.netcom.com
Subject: Re: [ARC5] Bear ''raslin', or, "The ATC and Me" (Very Long)
I have had an ATC,AN/ART-13B, and now have only the AN/ART-13A.All of them
worked after close visual inspection except the ART-13A. Someone had clipped
off the Jones connector to the antenna relay.I happened to have a Jones
connector that had the correct J-# stamped on it, so I proceeded to install
it.Well this was a Zenith built unit and it differs slightly from the
manual. It took me a whole day of wire tracing but I got it done.With
trepidation I applied DC only to the ART-13 and everything worked,including
the antenna relay. No broken glass here! After that I connected up the DY-17
and it loads very well to a dunny load.(N.A.F. DWG SK 980).Lights up all
the flourescent bulbs on the work bench too.
What shook me up was the first time I applied 28V DC to my first ATC.All of
a sudden, all the autotunes were spinning, the 813 and 811's were as bright
as light bulbs and I didn't know what the *HEY* was happenening. I just
about fell off my chair with heart failure!
So, yes I "rassled a cub ur two I spose"...
Jay KE6PPF
-----Original Message-----
From: Kenneth G. Gordon <kgordon2006 at verizon.net>
To: arc5 at ix.netcom.com; Discussion of AN/ARC-5 military radio equipment.
<arc5 at mailman.qth.net>
Sent: Sun, Jul 4, 2010 1:41 pm
Subject: Re: [ARC5] Bear ''raslin', or, "The ATC and Me" (Very Long)
Thank you, thank you, thank you, thank you, thank you!!!!!!!
I have an ART-13 which was given to me by a very good fellow. It has not
een so much as looked at for at least 40 years.
I am carefully hoarding your notes and will put them in "a safe place" until
I
m able to use them.
Ken Gordon W7EKB
n 4 Jul 2010 at 1:30, arc5 at ix.netcom.com wrote:
> An old friend asked me to help him get an early ATC
(sea-going ART-13) on the air. I'm close.... ;-)
When something is tough, I have a habit of calling it "a bear,"
meaning: "tough as wrestling a bear, and just as likely
to chase you up a tree." Or three...
I have resurrected some hard-case BAs,
but I ain't never had as tough a "bear" as this ATC.
I thought I'd pass along a few tips.
This isn't a "step-by-step"; a beginner should not even
try to 'rastle an ART-13, so I'm not going to cover
all the obvious stuff you already know.
It's just a "heads-up" on a few issues
for anyone who's "feeling froggy" enough to dust-off an ART-13.
1. Don't be in a hurry. You're not going to finish in one night.
Probably not in one week. It's going to be a long time before you put
power to this black monster. Slow down and think about everything
you're going to do before you do it. The ART-13 has a reputation for
being a "tough" transmitter. Don't you believe it. This thing is as
fragile as any 70-year-old, and just as hard to handle. Tipping or
turning it over without care and caution will result in bending or
breaking something, like the terrible "CRACK!" you hear when you turn
it over and the screwdrive you left on the bench crushes the vacuum
relay.... Don't ask me how I know.
2. If you don't have the Maintenance manual,
don't even think about turning the first screw.
Guessing and fudging just won't do on this one.
Get it. Read it.
3. The "Screw Gremlins" can smell you working
on an ART-13 from miles away and they will
come running. So get your bench and tools organized.
You'll need a full can of De-Ox-It or such
(NOT "Blue Shower;" that stuff should be sprayed
all over the guy that invented it).
Have a way to sort and keep screws and washers
(Ice trays turn over too easy.
Don't ask me how I know that one, either).
Important- A good, comfortable pair of insulating gloves.
You're going to be tweaking things that bite.
And if you get across that 1100 volts....
well.... you won't be worried about your ART-13 anymore.
4. All of you know not to try and pull the big tubes out
by the plate cap or glass, right? (Again- don't ask).
Put a screwdriver through the vent holes in the back,
under the tube bases and *gently* pry the tubes up
out of their sockets. Make sure you've released the
tube clamps at the bases before you try it.
5. OK- here's the first time the bear is going to bite
a hunk out of you. In order to lubricate the autotune
correctly, you're going to have to remove at least
"A" and "C" autotune mechanical thingies, one at
a time (they are not interchangeable).
Otherwise, you can't get to all the worm gears
or the line shaft bearings.
Instructions for removing "A" are in the most common
copy of the Maint. manual at 5-40 para 3 and
for removing "C" at para 4.
If you're lucking enough to have the big, full-on
ATC maintenance manual
NAVAER 08-5Q-6, FEB 1944,
the instructions are on the bottom of page 83.
Here's the first indication that even the revered
Collins can engineer something stupid:
They don't tell you in the instructions about
this little, brass dog-bone looking thingie that connects
the autotune dial to the thing it's controlling.
It has an indexed, toothed wheel on each end
and is about 3/4 of an inch long. It's not secured
on either end; it just fits into toothed,
indexed slots on each end.
So naturally when you pull the autotune out,
the little dog-bone thingie falls out, bounces on
the bench and flys down to the floor.
If you don't find it, you are a dead duck.
Worse is trying to fit it back together.
Don't move the clutched autotune stuff,
but you can rock the control shaft back and
forth until you get the cursed stupid thing to
engage on both ends. This shouldn't take more
than, oh, about 58 tries. If you force it,
it will bend and you will be unhappy.
Whiskey might help.
Don't try to take out the "B" HF Oscillator
multi-turn unit unless it's broken.
More on this nasty gadget later.
6. Once you get the autotune back together,
go do anything else until your sanity returns.
Then make sure all the locking bars on the tuning knobs
are tight and use a large-ish flat-blade screwdriver
on the end of the autotune line shaft and gently give it
a few turns to make sure nothing is binding or busted.
If you are one of the blessed that has the original
crank for the shaft, send me a private email
telling me where you put it
and when you go to sleep at night.
7. Here's a great big "gotcha" that happens in a lot
of WWII rigs- Ground lug oxidation.
I put a meter from the PA chassis to the Osc
chassis and it read 300 Ohms. Almost every ground
screw and lug in the whole rig was hi-Z. Give
a slight tightening turn to every chassis screw you
can see, and that will fix most of them.
Check each one.
But- unfortunately- there are several more deep
in the guts of the this big black troll, and you
must get to them. For instance: there's a stack
of parts right next to the 813 socket and it has
a ground lug on one of the screws. Yep- it was
hi-Z. You have to take the back cover off
(Not the screws holding the two relays. The relays
stay and the cover swings out of the way on the
relay wires) in order to fix it.
But that's an easy one. The real hair-puller is:
8. The Frequency Multiplier chassis.
Yes- it has to come out. And it's a pain to
take out. Putting it back is worse.
Grid resistors 25% high and hi-Z grounds.
Two slightly-leaky caps (look at the diagram
and you can test these parts without
pulling the chassis.... kinda).
If you need to pull this chassis, the procedure
is in the ATC manual on pages 70-71, and
in the more common ART-13 maint. manual
on pages 5-22 to 5-23.
Mark the wires from the Multipliers coils
or you will weep. I used colored dots on
the coils and wires to get them back
correctly. Be careful with the "folded"
connections to the bottom of the coils.
And be gentle- the coils can break
and some of the cores flake a little.
Important: Before you get up your courage
and remove the Multiplier chassis, get some
fingernail polish and mark the dial, the front switch
and the back switch so you are certain to
get them back together correctly.
The bandswitch segments are held together
with another Collins screw-up; a "U"-shaped clip
that holds tension on the segments and which falls-out
if you hold your mouth wrong. This clip is
not sold at WalMart. If the clip comes loose,
this can allow the rear bandswitch (2nd Multiplier)
to become mis-aligned,
and it took me three blankettyblankblank times of
pulling this chassis in and out to finally get it fixed,
all because I marked the front switch and neglected
to mark the back.
I fixed the hi-Z grounds and
replaced the bad resistors. The two caps-
a screen bypass and a cathode bypass-
leaked less than 200 microAmps at full voltage,
and would have been a nasty chore to replace,
so I left them in there. So shoot me....
All the grid caps and tank caps were fine.
More "gotchas" on the Multiplier chassis:
The tube clamps will hang when you try to remove
or replace the chassis. A screwdriver can push
them out of the way. The doubled lead that goes
to the LF oscillator will also be a pain unless you
remove it.
The big brass posts that connect the tube plate caps
are fragile and will snap-off easily, as I found out.
I wire-brushed the nut on top of the insulator
and the end of the broken post and, using
a good frame iron and non-acid flux, was able to
solder the post back in place with enough solder
to keep it secure... I think.
The round pink-n-brown multiplier tank caps
that you use to tweak the multi stages are
also quite fragile. Their adjustments will be "stuck."
The connection post on them is secured internally
with a rivet about the size of a flea's butt. It will
break off if you're not gentle with the cap, and
you won't find one of these at WalMart either.
This ATC won't be transmitting on 14.4-18 MC
because of this. Yet, you're going to need to apply
some amount of force to break the cap adjustments
loose so you can peak them. This flexes the connection,
so you might want to see just how much juju you can
get out of the rig without tweaking before you risk it.
I had to tweak this one, so I used a flat screwdriver
as a "punch" and the rubber handle of another screwdriver
as a mallet, and very gently tapped on the adjustment posts
over and over until the rotor came free.
Some of you mechanical whizzes
probably know a better way.
Use the insulated gloves when you tweak these
caps, or you shall surely get "lit-up" with 400 volts.
9. Once the transmitter was putting out RF,
I attempted to see the limits of the HF Oscillator.
Next thing I knew, the rig was stuck with the
osc. railed high, and wouldn't tune freq anymore.
So off came that end cover again.
This Osc-Mulitiplier set-up is a mix of genius and stupid.
Ok- let's see if I can describe this.
Imagine a coil. It has a core, which is fixed to a
long rod. The rod is threaded on one end
and is fixed in place so it can't turn on the other end.
The threaded end of the rod is screwed into the
threaded center of a cylinder. So if you turn the
cylinder, the threaded rod can't turn (because it's fixed
at the other end), so the rod moves in and out of
the cylinder. That's what moves the core back
and forth in the coil, and that's how you tune
the freq of the HF Oscillator in an ART-13.
It's a PTO.
So far so good. Now- the fixed end of the rod
is secured to a yoke that moves cores in and out
of two smaller coils, which are the tank coils of
the two multiplier stages. So- as we turn the
PTO dial, the core on the big threaded rod moves
in and out of the PTO coil, changing the freq,
and at the same time, the big threaded rod
(which is fix and can't turn- it just moves in and out)
moves the mulitplier tank coil cores,
peaking the mulitplier stages in sync with the PTO.
Genius, right?
Well, yeah... except for the way the long threaded
rod is secured to the yoke, which both keeps the
rod from spinning and moves the two smaller cores.
It's secured to the yoke with a #10 nut, a star washer
and a drop of 70-year-old Glyptol. That's it.
Nothing else. No key, no indexed slot, nothing
but friction and old paint. What were you thinking, Art??
So, naturally, the paint gave way when I got near
one end of travel and the nut and washer loosened.
Now the long threaded rod spins, the PTO core spins
and nothing moves anymore, regardless of where the
PTO dial is set. I was able to tell by the marks on
the guide bar where to re-secure it at the high end
of travel, within a rotation or so. I had to re-flex the
lock washer and secured the nut with a glob of
"Shoe Goo" (I think you could repair a battleship
with that stuff...it's good). It could just have easily
turned loose in the middle of travel, in which case
I'd have had a hard time getting it close.
So if you have an ART-13, do yourself a favor-
take off the case end and put a drop of something
on that nut to keep it from coming loose.
I guess that's all I can think of for tonight-
I still have a "gremlin" or two in the rig.
The 837 filament is intermittant, and I think that's going
to be another hi-Z ground lug at the LF osc. socket.
We'll see.
Hope this is helpful to any brave soul who tries
to tame this "black bear" of a rig.
73 Dave AB5S.
p.s. In case you didn't know---
I'm loving every minute of fixing this rig :-)
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