Edmund H. Ramm wrote:
In Andrew VK3BFA writes:

On Aug 18, 1:38 am, (Edmund H. Ramm) wrote:
In Andrew VK3BFA writes:


Are physics reversed down under? Up here in the old world a light
bulb's filament (tungsten) resistance increases with temperature.


Er - yes, thats correct.So whats the problem?

There will only be negligible inrush current limiting. For that you'll
need an NTC resistor like an Epcos NTC22. All you get from a light bulb
is a voltage reduction -mains voltage minus the voltage drop across the
bulb- but only AFTER the inrush current you intended to prevent has already
flown.

That lightbulb heats up pretty quickly, especially if there is a short
in the radio.

Just as a comparison:

a 250 watt bulb has a cold resistance of around 3 Ohms.

A 60 watt bulb, 18 Ohms

A 40 Watt bulb, 25 Ohms

I don't have a 25 Watt bulb handy, so I'm not sure of it's cold
resistance. But the other bulbs in that neighborhood are at around 14
times the resistance hot vs cold, I'll assume it is around 60 ohms.


Sorry for the math here, but R = V squared/P

That would equal around 58 Ohms hot resistance for the 250 watt bulb

240 Ohms for the 60 watt bulb

360 Ohms for the 40 watt bulb.

830 Ohms for a 25 watt bulb


I usually use a 25 watt bulb, so discounting any inductive effects, I'll
be looking at a maximum start current of 240 watts if the radio is a
dead short, and that for only a very short period of time.


A light bulb in series with an inrush current limiter might be suitable
for smoke testing equipment after prolonged disuse, though.

There isn't anything wrong with that approach, but it is probably overkill.

- 73 de Mike N3LI -

On Aug 16, 1:04*am, wrote:
Now retired I'm trying to become active again.
My TS-520S has not been on for 30 years.
I don't have a variactor ( variable transformer ).
At the TARC advice was to put a lightbulb in series
to take the surge. * Should I use a high resistance
( low wattage ) bulb or vice versa ?
Would this be as good as a simple *L-C network ?
Somebody said just plug it in. Are there any other
ideas ?
Thanks for your kind assistance.
Dave WB3DWE *Temple, TX

A couple of disclaimers first:

a) I know diddly/squat about Ham equipment. I am not a Ham.
b) I have been noodling about with vintage equipment, tube & solid-
state for now over 30 years, so I am familiar with the species. What I
write below is a generic approach to (re)starting vintage equipment
after some years at idle.

So:

As I understand, the Kenwood is a tube-based unit, however it has a
solid-state rectifier and is mostly solid-state in general. What this
means is that there is some validity to bringing up the voltage slowly
using a Variac as the caps will see a gradually increasing voltage -
unlike what they would see from a tube rectifier which does not pass
current until about 70V or so.

That it is from the transistor era, at least in part, suggests that
the filter caps may be of sufficiently recent manufacture as to be
likely to be good - the operative word here is *LIKELY*, not
*certainly*. Kenwood was also not know to use cheap-junk caps in their
equipment.

HOWEVER: A variac is really no better than a dim-bulb tester unless it
is equipped with a current meter (amps or watts) that will read the
actual current draw of the unit. I have been known to RANT on this
subject at length - but I will spare this group and merely state that
UNLESS you have the means to measure actual current drawn by the unit
and at a sufficiently fine degree as to give you useful data, don't
waste your time with a Variac. It gives you a false sense of
security.

IF you have the means to measure current - either with your VOM in
series or with a poor-man's ammeter (measure voltage drop across a 1-
ohm resistor, for example), this technique is very useful. Raise the
voltage s-l-o-w-l-y, watching the meter all the time. It will jump up
(typically) then slide down as the caps charge. Slowly-slowly-nicely-
nicely until you reach operating voltage over 4-5 minutes or so. And
KEEP WATCHING!

If the caps start to fail at full B+, you will see that meter creep
up. If they go anything beyond about 80% (SWAG guess - more below) of
the nameplate rating of the unit, you have real problems.

Now, here is where I cannot comment beyond the generic - I have no
idea what the quiescent vs. active current draw is with the Kenwood.
THIS IS IMPORTANT. As you will not be transmitting or whatever, you
should be operating at/near the quiescent current. This may be a very
small percentage of the full nameplate rating - my guess is that this
is so. You will need to know what that is. If you are operating even
5% beyond the "proper" quiescent current, that will be expressed as
heat somewhere - and eventually *POOF* at some unobtanium or expensive
part.

You get the point. The idea is to bring power to the beast slowly so
that failed caps or similar may be discovered before any actual damage
is done. For this to work you need a means to determine whether the
unit is taking excess current - and you need to be able to measure
this in fine-enough increments to be worthwhile. Otherwise, you are
wasting your time as a small problem or series of small problems will
be invisible to crude means.

I keep this unit for these sorts of tests:

http://www.oaktreeent.com/web_photos...P-5220_web.jpg

It is an metered Iso-Variac, overkill for once-in-a-while needs, but I
use it constantly.

Peter Wieck
Melrose Park, PA

On Aug 22, 5:06 am, " wrote:
On Aug 16, 1:04 am, wrote:

Now retired I'm trying to become active again.
My TS-520S has not been on for 30 years.
I don't have a variactor ( variable transformer ).
At the TARC advice was to put a lightbulb in series
to take the surge. Should I use a high resistance
( low wattage ) bulb or vice versa ?
Would this be as good as a simple L-C network ?
Somebody said just plug it in. Are there any other
ideas ?
Thanks for your kind assistance.
Dave WB3DWE Temple, TX

A couple of disclaimers first:

a) I know diddly/squat about Ham equipment. I am not a Ham.
b) I have been noodling about with vintage equipment, tube & solid-
state for now over 30 years, so I am familiar with the species. What I
write below is a generic approach to (re)starting vintage equipment
after some years at idle.

So:

As I understand, the Kenwood is a tube-based unit, however it has a
solid-state rectifier and is mostly solid-state in general. What this
means is that there is some validity to bringing up the voltage slowly
using a Variac as the caps will see a gradually increasing voltage -
unlike what they would see from a tube rectifier which does not pass
current until about 70V or so.

That it is from the transistor era, at least in part, suggests that
the filter caps may be of sufficiently recent manufacture as to be
likely to be good - the operative word here is *LIKELY*, not
*certainly*. Kenwood was also not know to use cheap-junk caps in their
equipment.

HOWEVER: A variac is really no better than a dim-bulb tester unless it
is equipped with a current meter (amps or watts) that will read the
actual current draw of the unit. I have been known to RANT on this
subject at length - but I will spare this group and merely state that
UNLESS you have the means to measure actual current drawn by the unit
and at a sufficiently fine degree as to give you useful data, don't
waste your time with a Variac. It gives you a false sense of
security.

IF you have the means to measure current - either with your VOM in
series or with a poor-man's ammeter (measure voltage drop across a 1-
ohm resistor, for example), this technique is very useful. Raise the
voltage s-l-o-w-l-y, watching the meter all the time. It will jump up
(typically) then slide down as the caps charge. Slowly-slowly-nicely-
nicely until you reach operating voltage over 4-5 minutes or so. And
KEEP WATCHING!

If the caps start to fail at full B+, you will see that meter creep
up. If they go anything beyond about 80% (SWAG guess - more below) of
the nameplate rating of the unit, you have real problems.

Now, here is where I cannot comment beyond the generic - I have no
idea what the quiescent vs. active current draw is with the Kenwood.
THIS IS IMPORTANT. As you will not be transmitting or whatever, you
should be operating at/near the quiescent current. This may be a very
small percentage of the full nameplate rating - my guess is that this
is so. You will need to know what that is. If you are operating even
5% beyond the "proper" quiescent current, that will be expressed as
heat somewhere - and eventually *POOF* at some unobtanium or expensive
part.

You get the point. The idea is to bring power to the beast slowly so
that failed caps or similar may be discovered before any actual damage
is done. For this to work you need a means to determine whether the
unit is taking excess current - and you need to be able to measure
this in fine-enough increments to be worthwhile. Otherwise, you are
wasting your time as a small problem or series of small problems will
be invisible to crude means.

I keep this unit for these sorts of tests:

http://www.oaktreeent.com/web_photos...P-5220_web.jpg

It is an metered Iso-Variac, overkill for once-in-a-while needs, but I
use it constantly.

Peter Wieck
Melrose Park, PA

Peter - lots of good stuff in there, but perhaps overkill..like the ac
power supply with its own meters - would be simple to use for the
methods you describe.

The Kenwood is a "Valve hybrid" - there are 3 tubes in there, a driver
and 2 output tubes in //. Filamnets are switchable on/off. Idle
current is.....very low, never measured it, had no need to. The light
bulb method does work sufficiently well for the purpose intended.

Andrew VK3BFA.

Andrew VK3BFA wrote:
On Aug 22, 5:06 am, " wrote:

Peter - lots of good stuff in there, but perhaps overkill..like the ac
power supply with its own meters - would be simple to use for the
methods you describe.

The Kenwood is a "Valve hybrid" - there are 3 tubes in there, a driver
and 2 output tubes in //. Filamnets are switchable on/off. Idle
current is.....very low, never measured it, had no need to. The light
bulb method does work sufficiently well for the purpose intended.


I think I missed just what type of rig it was. If it a Kenwood TS-830,
the owner has to immediately ship it to me, as those units had a
particular problem that ony I can fix.

I tested out one of those, and fell in love with it. Good sound, Hot
receiver, good looking rig, The big issue with those was the band
changing switch. Not a big deal.

Heck, I'll even pay shipping ;^)

- 73 de Mike N3LI -

Michael Coslo wrote:

I think I missed just what type of rig it was. If it a Kenwood TS-830,
the owner has to immediately ship it to me, as those units had a
particular problem that ony I can fix.


What a dummy I is. That's a TS-530, not 830

- 73 de Mike N3LI -

On Aug 17, 6:44*pm, Andrew VK3BFA wrote:
and its a pain in the
arse to set up, connect meters, gingerly spend time slowly
incrementing the voltage - life is too short to stuff around......

Hey, you got time to do Rocket Science, thats fine. Each to his own.

I think that turning it on, blowing up the capacitors that are gonna
blow up, and then replacing the ones that actually did blow up is a
fine procedure, myself.

There is a certain pussyfoot attitude about either cranking up the
variac gingerly, or simply recapping the whole radio, that is not
really appropriate to somebody (me!) who really wants to see smoke
coming out at least once in a while.

Only gotcha, if the bad capacitor takes out a transformer, that's a
PITA. Not that I've never rewound bad transformers or rewound them for
a project, but having to rewind a transformer just because I was
impatient is a little embarassing.

Tim.

On Aug 22, 2:52 pm, Tim Shoppa wrote:

I think that turning it on, blowing up the capacitors that are gonna
blow up,
who really wants to see smoke
coming out at least once in a while.

You been watching to much myth busters?

Only gotcha, if the bad capacitor takes out a transformer, that's a
PITA. Not that I've never rewound bad transformers or rewound them for
a project, but having to rewind a transformer just because I was
impatient is a little embarassing.

I think you going to has to jump the fuse to get away with that?
Nothing I hate more than shorted parts especially a shorted fuse.

73 OM
n8zu

In article
s.com, writes

A couple of disclaimers first:

a) I know diddly/squat about Ham equipment. I am not a Ham.
b) I have been noodling about with vintage equipment, tube & solid-
state for now over 30 years, so I am familiar with the species. What I
write below is a generic approach to (re)starting vintage equipment
after some years at idle.

....snip...
sounds good

Just to add. In the days when boat anchor stuff was the normal gear,
when items had been on the shelf in storage for long periods, the
electrolytics were not so good then as now

Switch on procedure from storage was:

1. Expect the odd "phut and horrible smell." It *will* happen at some
time.

2. Switch on for a few seconds and then off - allows the
electrolytic barrier in the capacitor to start to re-form - the number
of seconds for certain equipment was specified - otherwise about 5
seconds for the first time.

3. Switch off for about 60 minutes.

4. Switch on for 10 secs and then off for 30 mins.

5 Switch on for 30 secs and then off for 30 mins.

6. On for 30 sec off for 10 mins.

7. On for 60 sec off for 5 mins.

8. And so on....

These were valuable equipments and the manufacturer normally laid down a
procedure. The whole idea being to re-form the electrolytic capacitors
and to give other problems time to cool down for inspection and
detection/rectification.

The alternative was just to switch on and then stand back from the bench
with your fingers in your ears and a handkerchief over your nose

John
--
JC Morrice

On Aug 23, 7:35 pm, JC Morrice wrote:
In article





And so, like all good "tinny and bull****" sessions, we come back to
the original question - if Dave hasn't wandered off, in boredom or
disgust. And like all good amateur arguments, we have suggestions
ranging from ludicrous to....ludicrous.

We have had - an engineered, high tech solution
A stuff it, just power it up solution
The KISS solution - use a light bulb in series
The do it slowly and painstakingly with a metered variac solution
Some reminiscences about the "old days"
Someone else offered to buy the radio, but got their models mixed up.
Answers from people who, well, really....dunno why....

And all valid, all correct - so, Dave - take your pick which one YOU
use.......alternatively, there is a TS520/530/820/830 group on Yahoo.
You could post your question there - they have heaps of people who
lovingly use, restore these old radios - mind you, the answers will be
as broad spectrum as here, and LOTS more off em hi hi.

Andrew VK3BFA.

On Aug 23, 5:23*am, raypsi wrote:
On Aug 22, 2:52 pm, Tim Shoppa wrote:



I think that turning it on, blowing up the capacitors that are gonna
blow up,
who really wants to see smoke
coming out at least once in a while.

You been watching to much myth busters?

Not really, but a former schoolmate has worked at a place titled
"Center for Non-Destructive Testing" and my first comment to him (like
15 years ago) was "Where's the fun in that?"

Only gotcha, if the bad capacitor takes out a transformer, that's a
PITA. Not that I've never rewound bad transformers or rewound them for
a project, but having to rewind a transformer just because I was
impatient is a little embarassing.

*I think you going to has to jump the fuse to get away with that?
Nothing I hate more than shorted parts especially a shorted fuse.

The fuse is there to help (not guarantee) stop things from catching on
fire and burning down your house.

It's not there to save components.

It is sized based on primary current, not the current capacity of any
individual secondary or the components hooked to any individual
secondary.

Tim N3QE