[Hallicrafters] My work-up procedure for activating amateur tube rigs

[Kenneth Laine Ketner]

I’m still developing this, but here is what I have so far. Use at your
own risk, no guarantees, still under study, your mileage may vary, get a
ham license first.

Work-up procedure for reactivating stored tube rigs
by KA5ELD

PREPARATION PHASE
Unless you are an experienced tech with TUBE rigs, do not proceed
without a manual. Study the manual and schematics until you are familiar
with the general operation of the equipment, and the theory of its
function. There are many manual suppliers on the web. My favorite is
W7FG manuals ( www.w7fg.com ). Many manuals are available for free
download from BAMA at http://bama.sbc.edu/ . Many Swan manuals are
available for free download at http://6mt.com/ .

POWER SUPPLY (may be separate or may be inboard on the rig)
PS 1. BE SURE PS is NOT plugged into an AC source. While the power cord
is in your hands, check it for soundness. Take the cabinet parts off,
including bottom plates. Using a screw driver, ground to chassis all
plus terminals of electrolytic caps. (Yeah, I know it probably hasn’t
been plugged in for decades, but there is no such thing as probably
hurt, and it is a valid habit to form - always discharge electrolytic
caps before going into a PS the history of which you don’t know - tubes
are high voltage gear unlike transistors which are typically low
voltage.)
Clean cabinet parts with soapy water and brush. If the finish is bad, I
like to have mine powder coated (see the account at
http://www.w9wze.org/Restorations/PowderCoating/Powder_Coating_KA5ELD.htm
). Use a dry 1/2 inch paint brush and an air compressor to blow away
dust from chassis and parts (not just a cosmetic thing, because dust or
carbon traces can cause electrical problems).
Inspect for obvious damage or problems:
    burned out resistors
    bad solder joints (should look shiny, be complete, have no
graininess or dull gray)
    loose or frayed wires/damaged insulation
PS 2. Use ohmmeter to test diodes - normal is low resistance in one
direction, high in the reverse direction. Radio Shack has replacement
2.5 Amp 1000 PIV cheaply which should work in Swan PS ok.
PS 3. Check all grounds, especially tighten grounds bolted or screwed to
chassis (ground connections are part of the circuit too). Sometimes the
ground is thru a pot or switch mounting bolt - check those to see if
they are firmly tight.
PS 4. Check electrolytic capacitors preferably with a capacitor tester
which will slowly apply working voltage (bring the voltage up slowly
arriving finally at the working voltage with little or no leakage - if
there is leakage after a forming period, replace). One has to remove one
lead of the cap to get a good leakage test and for a good re-forming. It
is better to reform caps singly instead of bringing them up all at once
with a variac, because “complex systems fail in complex ways.” Better to
get some surety about these crucial components in the PS instead of
relying ONLY on a variac initial start (which should still be done). If
you have not reformed electrolytic caps, get some info on it (a web
search for REFORMING CAPACITOR using google will yield several sources
of info, such as http://www.angela.com/catalog/how-to/about_caps.html .
If you can get or borrow a Sprague Tel-Ohmike or one of the Heathkit cap
checkers, you will have the circuits to handle caps of all kinds.
PS 5. If there are any paper or molded plastic caps (non-electrolytics),
replace those with contemporary 600 v caps (such as the molded yellows
from Antique Electronic Supply). In some cases, a higher working voltage
may be called for - it is ok to use a higher working voltage in the
replacement, but not a lower value.
Test continuity on transformers and chokes. Test and secure all mounting
bolts on transformers and chokes - if they are loose the components can
mechanically buzz when active.
PS 6. Check resistor value with an ohmmeter. Carbon resistors tend to
age higher, sometimes quite a bit higher. Crucial resistors in the PS
(for example, bleeders) might need replacing. I replace with Metal Film
Resistors. Source for Capacitors and Resistors: Antique Electronic
Supply in Tempe AZ (www.tubesandmore.com).
PS 7. If there is a speaker in the PS, dust carefully with dry paint
brush and air. Check to see that the cone travels freely, and that the
cone is solidly attached to the voice coil form and to the frame (one
source of audio distortion is a loose cone or a voice coil form that
drags on the armature or has come loose from the cone. If you got
speaker problems, there are procedures for fixing them, but that is a
different topic. Check speaker coil and cable for continuity (a faded
1.5 v AA cell makes a good source of low voltage for testing onto the
plug end - if the speaker makes clicking sounds, the cable and speaker
are ok).
PS 8. Check and clean connecting cable from PS to rig.
PS 9. Check the value of the fuse — VERY IMPORTANT - Is it the value
called for in the manual?

THE RIG
R 1. BE SURE the rig is not connected. Remove the top cover and the
cover on the final amplifier compartment, and KEEPING YOUR HANDS OUT OF
THE PA COMPARTMENT, use a screwdriver to ground the plate cap(s) on top
of the PA tubes to ground, likewise ground the top of the high voltage
plate choke (the thingy that the supressors coming off the plate cap(s)
are connected to). Remember these are PLATE caps, not grid caps as on
entertainment broadcast tube radios for living rooms etc. Plate caps use
hundreds of volts, whereas grid caps usually very little voltage.
R 2. Perform the Power Supply procedures PS 1,PS 3,PS 4,PS 5 on the rig.

R 3. Remove tubes one at a time. As you do so, check to see if the
proper tube is in the proper socket. A common problem is a wrong tube,
or a “substitute” that is not really a proper sub. Label sockets with
pencil if they are not already marked with tube numbers. Clean each tube
with a dry rag (dampness will often remove the lettering), and clean
pins with a small wire brush - again this is not just cosmetic - dust
can cause heat buildup or electric tracks. Test the tubes. Replace tubes
with a good set - as you put each tube back into its socket, brush a
small amount of CAIG Labs GXL100 onto the pins (see
http://www.caig.com/prod.htm for info on Progold GXL and Progold spray).
In a similar fashion clean and test all dial lamps and be sure the right
kind are installed — wrong ones can upset tube filament circuits.
R 4. Spray Caig Progold into all potentiometers and switches (but not
wafer switches). Flex or operate the pot or switch a few times. Use GXL
and a small artist’s brush to paint the contacts of all wafer switches,
and the Jones connector plugs on back panel, as well as the RF input
(antenna connector) and any other metal to metal contact such as plugs.
R 5. Check all variable caps For cleanliness between plates, and that
plates are not touching. Use a light machine oil to lube the
ballbearings of the cap - can apply with a toothpick. Paint GXL on the
wipers of variable caps. Operate to distribute the stuff. Paint GXL on
all relay contacts, then use some 600 wet/dry sandpaper strips to pull
thru the contact points - rough side up, rough side down on the NC, and
then hold pressure to do the same with NO contacts. Maybe 6 or 8 passes
are indicated per side per NO or NC. Reapply a small amount of GXL to
relay contacts.
R 6. Reassemble the PA compartment and its cover. For any powered tests,
always have the cover ON the PA compartment. When removing the PA cover,
routinely check that the rig has been disconnected from power source for
about 5 minutes then always ground the PA high voltage after removing
the cover.

THE SMOKE TEST
This assumes that one has has a manual which has been studied and that
one has performed the above PS items and R items as a minimum, and that
needed repairs have been made.
S 1. Arrange components on a comfortable and safe area. Have the PS in
its box, and the rig out of its cabinet, but the PA cover on. Connect an
antenna. With the rig turned off and the variac turned off, connect the
rig to a variac or other course of variable AC power of sufficient
capacity (usually 120 VAC). It is best if the variable AC input is
metered so one knows the level of AC going in the set. For sets with
tube rectifiers, with the set turned off, set the variac to put out 60
VAC (with sets having diode rectifiers one can start the variac at 25
volts).
S 2. Turn off the variac. Turn the set on. Nothing is happening yet. But
time has come to see if any smoke will leak. Use the manual to configure
the set for receive only, power switch on. Double check the settings. I
usually set RF gain full on and Audio gain full on to start.
Turn on the 25 (or 60) VAC variac. Since the set is already on, you
should see some activity, especially the dial lamps should glow just a
bit. If they don’t, stop and turn variac off. Figger out why those dial
lamps don’t light. Once they are lighting, let the set run on low variac
voltage for a while. Observe the tube filaments. Are they lighting? They
will typically begin lighting around 60 VAC on the variac, sometimes
lower. If each and every tube filament is lighting, you may raise the
voltage in 5 volt steps, listening for some audio and watching for smoke
or noise or anything out of the standard - the first thing you hear may
be receiver hiss. If you hear it, peak up the preselector or grid
control for max hiss. If there is a PA plate current meter on the set,
keep an eye on that, and if it reads anything while configured for
receive, shut down and figger that out. No transmit functions should be
happening now.
I usually begin to hear the receiver, if everything is proceeding well,
at around 70 volts variac input. If you are hearing it, let it run at
that level for a while, and again observe for anything out of the way.
Raise the variac by about 5 volt steps, and tune the controls for
reasonable receiver operation. If it will run without incident at 110
VAC, then it should be ok for running directly off the 120 VAC wall
socket. Once it will run off the wall socket, you are ready to test the
transmitter portion, and to begin general trouble-shooting and alignment
(which I won’t venture into at this point).

While there are a number of good books on receiver servicing, such as
PRACTICAL RADIO SERVICING, by William Marcus and Alex Levy, or
ELEMENTS OF RADIO SERVICING, by the same 2 guys,

I don’t know of a similar book for trouble-shhoting a transmitter. If
anyone got one for that (other than the ARRL handbook, which is more
theory than actual practical service procedures), please let me know.

Keep ‘em lit, and be careful while having fun,

es 73 de KA5ELD


--

Ken Ketner
ARS KA5ELD (Extra Class)
  Personal Webpage: http://www.wyttynys.net
  Office Webpage: http://www.pragmaticism.net
Email:
 home: ketner at arisbeassociates.com
 office: b9oky at ttacs.ttu.edu

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