T-368 repairs, help if you can, thanks

[wb3eii]

Hottest day of the year (so far) found me on the Garden State Parkway with a
new-to-me t3 in the back of the pickup. Almost 3 hours later I'm home, hot, and
happy. (though not happy about being hot, truck should have been ordered with
A/C)
Unit is in OK shape, needs a few items, but it is nice.

I'd like to enlist some help, these are the items I can see missing.

1) C9, (the bigger of the two vac caps). 1500 pf is what is called for, no idea the voltage rating, probably 3 to 4 kv is sufficient.

2) J8 (the chassis socket that accepts p101, the 15 pin amphenol plug from the
exciter) If any one has a parts chassis, could you leave about 2-3 inches of
wire on the j8 socket? (it would be easier to match the all the wires by color
and tracer). Somebody needed this socket, probably to use the exciter in some
other rig.

3) T10,I don't know what this transformer does, it is not listed on the
schematic I have. But there is a hole in the chassis with "T10" next to it, and
a few loose wires under the hole.
(update T10 is a ferro-resonant regulator transformer, 6 to 6.3 volts, feeds heater voltage the exciter)

4) A schematic for the "B" variant, the book I have is for the base model. (found the scheme on BAMA)
 
5)Blower fan for the PA tube is missing also, a small squirrel cage type.

Many thanks, Ed, AB3HT

[flintstone mop]

I am of no help in the missing items....BUT I hope you got a good deal on a non working T3..........like $250 or free!

[WBear2GCR]

There are more or less mandatory mods that take the DC (B+) off the output tank.

The missing blower is it the one on the RF deck or the big one that pushes air through the entire unit?

For the big cap, oddly mine is/was missing that one too. The higher the voltage rating the better, I'm not sure what I got to put into my RF deck. There is likely more margin without the bias of the B+ sitting on that cap...

Take a close look at your three front panels. If they actually match, you may have a rig that is original. A whole lot of them were mixed and matched when sold surplus. Mine has an aluminum front panel, engraved, and steel mod deck and PS deck. My PS deck has the B+ iron that has both the 110 and the 220 windings, the hermetically sealed box style.

Not sure if this helps you at all...

                     _-_-

[KA3EKH]

Be careful if it’s not got the original base and some idiot ham attached casters or other small size wheels to the bottom of the cabinet! Also heed the warning on never pulling out all the drawers at once. And the screen shunt control for the PA is a real joy to work on if you not done that before. Some people have been known to remove the original blower and replace it with smaller and quitter blowers on the back of the case. Fair Radio had several parts units for a while and maybe you can get what you need from them. One thing I have noticed on the three or four of the T-368 that I have seen around for sale is that’s there are generally very clean unmodified ones that were never used and Ham hacked ones that have poor quality work on the power supplies, stupid modifications to the audio deck and things like that, for some reason those always seem to have carpet casters screwed to the base. But not a lot in-between, maybe the people who have kept them working and did good quality stuff hold on to threes forever? Can’t understand the last couple that I have seen being if you not capable of maintaining or understanding that sort of transmitter in the first place why did you get one? Is there some rule that if you want to be a Big AM operator you have to have an R-390, T-368 and a D-104?

[wb3eii]

"Is there some rule that if you want to be a Big AM operator you have to have an R-390, T-368 and a D-104?"
 I just got it 'cause t3's are way cool, a DX-100 is cool, but a t3 is way cool.(that and the fact that a Harris MW-1 is just too big)
 I hope to find some of the missing pieces at the Sussex Hamfest this Sunday, Thanks All. (look for me here again, I might not find all the missing pieces.)
 Ed AB3HT

[W3GMS]

"Is there some rule that if you want to be a Big AM operator you have to have an R-390, T-368 and a D-104?"
 I just got it 'cause t3's are way cool, a DX-100 is cool, but a t3 is way cool.(that and the fact that a Harris MW-1 is just too big)
 I hope to find some of the missing pieces at the Sussex Hamfest this Sunday, Thanks All. (look for me here again, I might not find all the missing pieces.)
 Ed AB3HT

I am sure you understand the transmitter just fine!  Your just looking and asking for some help from those that are familiar with the transmitters.  I have had one for about 20 years and its a wonderful transmitter.  I also used one when I was a CW Signal Instructor in the Army at Ft Gordon.  Let me go through the documentation I have and see if I can get a voltage rating on the capacitor your missing.  Sorry but I don't have any spare parts otherwise I  would definitely help you out.  As far as the audio quality, its not bad but definately communication quality.  So depending what your trying to achieve, various mods are well documented and proven.  I would recommend you get it on the air stock first and see how you like it and then go from there.  

Have fun with the rig its a great one.  B&W was the designer and the former owner Jack Williamson -W3GC (sk) was a good friend of mine.   I enjoyed listening to all the stories about how they got the contract to do the 368 as a follow-on to the BC-610.  

The Army used them with R-390's in the back shelter of a 2 1/2 ton truck.  The radio set was called a 26 Delta.  

Have fun with it.

73,
Joe, W3GMS          

[flintstone mop]

A military manual to the model you have would help you to see what is missing and then you start your search for the missing parts. Fair Radio might be a place to get parts.
 
Here's a link for the manual.

http://www.vintagemanuals.com/search.php?find=T-368
The prices do not scare me........or find a cheaper source for a complete military manual somewhere on Al Gore's internet. I would not tackle something like the T-3 without a complete road map.

I have a manual for the T-3 I owned at one time, I would never let it go, as I plan on grabbing another one on a lucky day. If you have only the schematic, that will not be much help. You need the complete military manual with illustrated pictures showing you where all of the components are located.
To get you started, if you could share some pictures of what is missing, we can help a little.
Fred

[pa0ast]

Four T368 manuals on Bama, for free!!

[flintstone mop]

PA0ast...Do you have a link? I see free BAMA manuals for the antenna tuning unit. Nothing on the chassis or schematics for the three drawers.

[W2NBC]

http://bama.edebris.com/manuals/military/t368/

There are some other sources as well!

[flintstone mop]

http://bama.edebris.com/manuals/military/t368/

There are some other sources as well!
[/quote
A patient approach to the slow download and lo and behold. Good source.

[wb3eii]

Yep, got the pdf from BAMA. Covers the 'b' variant, I found out what the missing transformer is.(I have the paper manual from Nov.  1955, which covers the Basic model only.)
 The missing blower is the one on the PA deck, not the one inside  the back of the cabinet.
 Curious to know about the "more or less mandatory mods that take the DC (B+) off the output tank".
 All of my drawers have the same lot number on them, so at least I know this wasn't pieced together.
 I could likely replace the missing transformer with most any 6.3 volt heater transformer.
 The missing "J8" socket is what may prove tricky, I don't want  to retrofit a completely new coupler group here as the space is tight.
 Thanks for the input, and keep those comments coming.
73 Ed .

[WBear2GCR]

the mods that take the B+ off the tank have been discussed here in the forum, so you can search for T-3 and T-368 and probably come up with that pretty quickly. Also I think that on the left side of the button bar that is just below the main banner on this page is something called "The AM Window" when click you will find a bunch of docs on various rigs, and this mod may be amongst them, but I have not looked in some time, so I am just guessing.

                      _-_-

[K6IC]

Hi Ed,

The TimTron mods are on the AM Window of this site.  These include the removal of the DC from the Plate Tank and from the "Plate Current" meter:

http://www.amwindow.org/tech/htm/t368.htm

You need not do all of the Tron mods,  but they are a good read.

EDIT: And,  Bruce,  W1UJR still appears to have his site up,  with quite a lot of T-3 info:
http://www.w1ujr.net/t368.htm

The Depot Repair/Maintenance Manual -- the Military manual with the --35 designation in the Military number for the manual is the most comprehensive manual,  but the Operation manual is also useful.

The missing loading Vac Variable was something in the range of 2000 pf,  and if the DC is removed from the Plate Tank,  this cap would not need a very high voltage rating for any rational antenna impedance.

When I get nearer my T-3,  will try to find the ratings on the Loading Cap.

More later,  Good Luck,  Vic

[wb3eii]

 To all who have replied, your help is greatly appreciated.
 I attended the Sussex NJ hamfest this past weekend, found some nice 4-125's and a 4-400, so I am that much closer.
 The big vac cap I didn't find, but I have a few leads to follow.
 Thanks for the links to the HV mods, the audio mods are easy to find but I couldn't find the RF deck mods previously.
 I have a few Hammie Hambone mods I need to reverse (blower was removed from RF deck and a second PA tube socket was installed), otherwise, no major faults are visable.
 This should be a nice project. 73 ED

[wb3eii]

OK, I found a suitable load cap, an 8 to 1400pf 3kv ceramic. voltage rating should be fine, since I plan to modify the output tank.
 I still need the 15 pin amphenol socket, and the PA tube blower.
73 Ed.

[wb3eii]

 Update;
 15 pin amphenol socket has been located and re-installed.
 PA blower replaced with a slightly smaller (but much quieter) fan.
Since I don't plan on running tty  I believe I have enough air flow.
 Next up is solid-stating the MV supply, (PO did the HV already)
 More to come as the project progresses.
 73, Ed

[wb3eii]

And now a question.

As delivered, the t-368 had all of the transformers that  supply filament voltage wired on the 115volt tap, there is also a 120 volt tap.
 Voltage at my QTH is around 123 v, I plan to swap the heaters over to the higher volt taps, should I be concerned with the B+ voltages as well?
73, Ed.

[W8VG]

Good luck with the T-3!  I love mine.  Made the Tim Tron mods to final and am using N9FOY speech amp (requires line level audio from my audio chain).

Works and sounds great! 

Over the years have had to modify/replace a few items to keep it going--it was made about the same year as me <hihi>.  Completely re-did the power supply deck a few years ago to eliminate some arcing and re-sealed leaky insulator of HV choke to stop Pyranol leak <ugh!>.  But transmitter sounds great on air and is built like a brick outhouse!  Make sure the floor is strong under it <hihi>.  Also nice to have 20 year-old son to help you move and lift the decks. 

Definitely recommend Bruce's website and printing/punching manuals in nice big handy binder--all great references. 

Operate mine with back off and smaller blowers on the Mod deck/internal blower in RF deck.....seems to stay cool enough for general AM fone use (Mil RATT duty cycle would be another story me thinks).

Go for it!  Can't wait to hear it on air--which I will eventually.  I make the East Coast during winter on 75 and used to work EU stations regularly around 3705/3710 when I lived in VA.  Will definitely make for big signal with healthy antenna.   Hoooooah!

73's,
Geo W8VG
Fullerton CA

[wb3eii]

 T3 lives again!
 Did some testing into dummy, getting 450 watts carrier, apparently modulation is ok also, as I get swing on the meter when talking.
 Will try some on-air tests shortly, look for me on 3705.
 Ed, AB3HT, ex wb3eii

[N2DTS]

Its great that it lives again.
Fair radio used to sell all the parts for reasonable prices, a long time ago.
I got some at the time, iron and the pto exciter deck.