RadioBanter - View Single Post - SBE-33 Repairs -

June 14th 06, 05:19 AM posted to rec.radio.amateur.boatanchors

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