Howdy - WDØHCO Biz here ...

I am working on a moldie oldie - an old SBE-33 - one of the first
transistor/hybrid tube rigs of the mid-60's. This rig was new when "I Dream
of Jeannie" was broadcasted on NBC - 42 years ago I think.

Well anyway that's what I remembered - the rig is fixed and working great -
but every now and then the "PA Load" cap shorts to ground and output goes
bye-bye.

Old Faust Gonset used a trimmer cap for the PA LOAD. It's an ARCO L305
compression trimmer type - no value on the schematic but I am assuming its
180 mfd by the size.

Question is... has anyone worked on this and I am thinkin of pulling the
whole thing out and putting a "REAL" variable cap in it's place.

Opinions Please... thanks - B

"WDØHCO - Biz" wrote in message
...
Howdy - WDØHCO Biz here ...

I am working on a moldie oldie - an old SBE-33 - one of the first
transistor/hybrid tube rigs of the mid-60's. This rig was new when "I
Dream
of Jeannie" was broadcasted on NBC - 42 years ago I think.

Well anyway that's what I remembered - the rig is fixed and working
great -
but every now and then the "PA Load" cap shorts to ground and output goes
bye-bye.

Old Faust Gonset used a trimmer cap for the PA LOAD. It's an ARCO L305
compression trimmer type - no value on the schematic but I am assuming its
180 mfd by the size.

Question is... has anyone worked on this and I am thinkin of pulling the
whole thing out and putting a "REAL" variable cap in it's place.

Opinions Please... thanks - B

Two or three ideas.
The L305 has a capacitance range from 190 to 760pF (source
http://www.arco-electronics.com/prod...e_categoryID=1
) if you are considering a replacement. Not an entirely bad idea.
Those Arco's are not hard to repair if you can get it out in your hands
to work on it. Most shorts come from mica dielectric sheets between the
plates that have cracked, shifted, or were too thin for your RF voltages to
begin with. Old Arco's from the junk box (or your favorite Ham's junk box)
are a source for new mica sheets if you find one or two that need
replacement.
I like stuff relatively unmodified, but hey, whatever you choose!
Old Chief Lynn, W7LTQ

in article , Lynn Coffelt at
wrote on 6/6/06 12:48 PM:


"WDØHCO - Biz" wrote in message
...
Howdy - WDØHCO Biz here ...

I am working on a moldie oldie - an old SBE-33 - one of the first
transistor/hybrid tube rigs of the mid-60's. This rig was new when "I
Dream
of Jeannie" was broadcasted on NBC - 42 years ago I think.

Well anyway that's what I remembered - the rig is fixed and working
great -
but every now and then the "PA Load" cap shorts to ground and output goes
bye-bye.

Old Faust Gonset used a trimmer cap for the PA LOAD. It's an ARCO L305
compression trimmer type - no value on the schematic but I am assuming its
180 mfd by the size.

Question is... has anyone worked on this and I am thinkin of pulling the
whole thing out and putting a "REAL" variable cap in it's place.

Opinions Please... thanks - B

Two or three ideas.
The L305 has a capacitance range from 190 to 760pF (source
http://www.arco-electronics.com/prod...ductlineID=12&
productline_categoryID=1
) if you are considering a replacement. Not an entirely bad idea.
Those Arco's are not hard to repair if you can get it out in your hands
to work on it. Most shorts come from mica dielectric sheets between the
plates that have cracked, shifted, or were too thin for your RF voltages to
begin with. Old Arco's from the junk box (or your favorite Ham's junk box)
are a source for new mica sheets if you find one or two that need
replacement.
I like stuff relatively unmodified, but hey, whatever you choose!
Old Chief Lynn, W7LTQ




Lynn - YOUR THE MAN !!

I looked on Google for an hour and gave up and here your got the info right
there - Well anyway I was lazy and tried to order the cap - you know the
drill - gotta order through the distributors - called several - all say
minumum order required - 4 weeks delivery -

So I took your suggestion and tried rebuilding it - didn't have the exact
cap in the junkbox but had several that same physical size - the hardest
part was getting that little bugger out of the rig!

Took it apart and your right - there where several places where RF had punch
some holes in the Mica - pretty small but you could see it without a mag
glass - Replaced the sheets and borrowed a friends digital cap meter to
check out the range - re-installed and now it tunes correctly -

Interesting design - I wondered why they would use a padder cap for final
tune - guess it was the only way to get 700 pikes in such a small space so
you can tune a wide variety of ants - if you were going to use this with an
amp you could get away with a small vairable with 360 pikes or less.

Overall the whole TX side was designed for low level duty cycle - typical
SSB. If someone tried RTTY on this thing I have no doubts it would blow up
in 10 minutes - The design was ahead of its time in the early 60's. No way
this 42 year old radio can keep up with today's jap rigs - still it works
well enough to use everyday on 40 and 80.

The filament situation still bothers me - in the 60's tubes were 90 cents
each, gas was 35 cents a gallon and electricity was 2 cents a kwh. Ah the
good ol days!

Today, its different and I want those tubes OFF when I spend time listening
on the bands - but I'm like you Lynn, hate to drill holes and ruin a nice
piece of equipment.

Then it came to me - if I could find a 10k pot with a switch, I could
replace the Mic Gain pot and turn the Filaments ON/OFF with the Mic Gain
control. Only need Mic Gain when the transmitter is ON anyway so it makes
sense and I don't have to drill a hole for a toggle switch.

So that's the next project!

Thanks for all your help! - Biz WDØHCO

I looked on Google for an hour and gave up and here your got the info
right
there - Well anyway I was lazy and tried to order the cap - you know the
drill - gotta order through the distributors - called several - all say
minumum order required - 4 weeks delivery -

So I took your suggestion and tried rebuilding it - didn't have the exact
cap in the junkbox but had several that same physical size - the hardest
part was getting that little bugger out of the rig!

Took it apart and your right - there where several places where RF had
punch
some holes in the Mica - pretty small but you could see it without a mag
glass - Replaced the sheets and borrowed a friends digital cap meter to
check out the range - re-installed and now it tunes correctly -

Interesting design - I wondered why they would use a padder cap for final
tune - guess it was the only way to get 700 pikes in such a small space so
you can tune a wide variety of ants - if you were going to use this with
an
amp you could get away with a small vairable with 360 pikes or less.

Overall the whole TX side was designed for low level duty cycle - typical
SSB. If someone tried RTTY on this thing I have no doubts it would blow up
in 10 minutes - The design was ahead of its time in the early 60's. No way
this 42 year old radio can keep up with today's jap rigs - still it works
well enough to use everyday on 40 and 80.

The filament situation still bothers me - in the 60's tubes were 90 cents
each, gas was 35 cents a gallon and electricity was 2 cents a kwh. Ah the
good ol days!

Today, its different and I want those tubes OFF when I spend time
listening
on the bands - but I'm like you Lynn, hate to drill holes and ruin a nice
piece of equipment.

Then it came to me - if I could find a 10k pot with a switch, I could
replace the Mic Gain pot and turn the Filaments ON/OFF with the Mic Gain
control. Only need Mic Gain when the transmitter is ON anyway so it makes
sense and I don't have to drill a hole for a toggle switch.

So that's the next project!

Thanks for all your help! - Biz WDØHCO

Great! Gives me some encouragement in my Knight T-60 project!
Lynn, W7LTQ

"WDØHCO - Biz" wrote in message
...
in article , Lynn Coffelt at

wrote on 6/6/06 12:48 PM:
'''snip...

Then it came to me - if I could find a 10k pot with a switch, I could
replace the Mic Gain pot and turn the Filaments ON/OFF with the Mic Gain
control. Only need Mic Gain when the transmitter is ON anyway so it makes
sense and I don't have to drill a hole for a toggle switch.

So that's the next project!

Thanks for all your help! - Biz WDØHCO



Kudos, Biz. Don't kill the good ones just for some special, private mod.
I had one of these and the T/R relay got erratic - ear-splitting noisy on
Rx. I probably could have fixed it with a little creative bending, but sold
it.

73, Steve, K9DCI

in article , Steve N. at
wrote on 6/13/06 1:46 PM:


"WDØHCO - Biz" wrote in message
...
in article , Lynn Coffelt at

wrote on 6/6/06 12:48 PM:
'''snip...

Then it came to me - if I could find a 10k pot with a switch, I could
replace the Mic Gain pot and turn the Filaments ON/OFF with the Mic Gain
control. Only need Mic Gain when the transmitter is ON anyway so it makes
sense and I don't have to drill a hole for a toggle switch.

So that's the next project!

Thanks for all your help! - Biz WDØHCO



Kudos, Biz. Don't kill the good ones just for some special, private mod.
I had one of these and the T/R relay got erratic - ear-splitting noisy on
Rx. I probably could have fixed it with a little creative bending, but sold
it.

73, Steve, K9DCI



Well had nothing to do today so I thought I'd go ahead with the tube
filament mod.

First thing was to search the old junk box. Found a nice 5K POT with a
switch to replace the original 10K Mic Gain. As it turns out, 5K is all you
need for mic gain with the standard SBE hand mic. If you use the SBE power
mic you might have to use all 10k if you dont know how to turn down the
pre-amp inside the mic base.

To replace the pot you have to dismantle the whole front face plate. While I
was doing this I notice the speaker had a hole in the cone. I walked
backwards into the XYL's bathroom and got her "Sally Hansen Hard as Nails".
It's great for repairing speaker cones and for use as "arc dope". The only
drawback is when the XYL finds out and starts with the QRM. Usually ends
when she says her cosmetics closet is not a tool box. At this point she
sends something flying usually in my direction and at this time I QRT to the
ham shack.

Assembled the whole front panel and gave a few transmissions - works
perfectly with the new pot - now to turn the filaments off.

Studied the schematic and looked around near the finals - right there on PIN
#5 of V3 was a small un-insulated wire tied to a terminal board. Usually an
un-inslated wire means a option of some sort so with the rig ON and the HV
B+ flowing to the plates - I slowly brought my dikes to the uninsulated wire
and snipped it. All of sudden all tubes when dark - AHHH... PERFECT !!! I
then took 2 5" pieces of #26 gauge wire and twisted them together - hooked
up one end to pin #5 of V3 and the other wire to the terminal board where
the un-insualted wired was tied to. The other ends where then soldered to
the switch. Now to turn ON the radio - oh **** it WAS ON ! I guess angels DO
EXIST! well to make a short story long - I can now turn the filaments ON/OFF
by using the mic gain control - few contacts later - none reported any 60
cycle hum over the mic audio - it's as clean as can be.

So now I can listen all day and just fire up the tubes when I need 'em.

Clearly Faust Gonset - thought hams would this mod for port/mobile to keep
current demands low.

Next mods

(1) Amp Control - don't have the SBE SB-1LA amp. SBE 33 provides +10 VDC
during XMIT and 0 VDC during RX. Mod would insert a 10V relay or Reed Relay
to control my AMERITRON 811. Will put everything inside the rig.

(2) Replace #49 bulb with a superbright White LED - but can wait until the
49 burns out.

(3) Add superbright RED LED which only lites during during XMIT. Lots of CB
sets do this - stupid but what the hell! I'll put my foot down on the rodger
beep. HI HI

(4) last mod - replace RCA female ant connector with SO-239 so it matches
all my other rigs and cables.

Also planning to paint the cabinet light blue and add some extender feet to
the front.

After all - that is it still an SBE 33 ?

I don't know..... but at least its mine. :^)

- Biz WDØHCO