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Author Topic: T368 comes home!  (Read 29687 times)
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ke7trp
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« on: January 16, 2010, 09:58:51 PM »

Got the T368 today.  Took some crapy pictures as I forgot the camera on the way out the door.  This unit belonged to my Friend WD7I. He lost his battle with cancer recently. WD7I got the unit from W8QBG who rebuilt it.

So far so good.. I made the "mating cable" up for PTT and mute.  It makes full Power.  The Blower is so loud I cant hear myself think.  It has to be bad.  I am going to look into that this week.  Here are the pictures.

Clark


* Photo_011610_001.jpg (254.8 KB, 1280x1024 - viewed 562 times.)

* Photo_011610_003.jpg (227.12 KB, 1280x1024 - viewed 486 times.)

* Photo_011610_007.jpg (209.15 KB, 1280x1024 - viewed 516 times.)
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ke7trp
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« Reply #1 on: January 16, 2010, 09:59:44 PM »

More pictures.


* Photo_011610_011.jpg (396.05 KB, 1280x1024 - viewed 497 times.)

* Photo_011610_012.jpg (371.86 KB, 1280x1024 - viewed 513 times.)
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WA1GFZ
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« Reply #2 on: January 16, 2010, 10:09:10 PM »

Now you just need to locate some 6000s and you will be set for life.
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N2DTS
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« Reply #3 on: January 16, 2010, 10:15:18 PM »

What a beast!
I have heard some that sounded very good.

Do you really need a blower?
They are built like tanks, if you don't strap the tubes, I am sure all you need is some gentle air flow...

Brett
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WA1GFZ
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« Reply #4 on: January 16, 2010, 10:20:02 PM »

4-400 needs good air flow through the socket. check out Eimac spec.
blower bearings need changing
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ke7trp
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« Reply #5 on: January 16, 2010, 10:47:24 PM »

Yep.. Got some work to do:

1. Rebuild blower or replace.  I have two Big Dayton units. Maybe one will fit.  Variac the blower to kill some RPM off.  Ham use at lower power does not need this much fan.

2. Figure out how to hook the audio rack to the 600 ohm balanced input.. I tried without any luck.

3. Bypass Clipper and Speech filter.

Thats about it. Its a clean stock restored T3 and it needs little.

Clark
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N2DTS
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« Reply #6 on: January 16, 2010, 10:55:54 PM »

The 30K1 used a 4-125 in the final with no blower/fan.
I put a 4-400 in without air, never had a problem, running over what I did the 4-125.

The globe king 500 used a 4-400 (or was it a 250? ) with just a wimpy little fan.

Brett

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ke7trp
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« Reply #7 on: January 16, 2010, 11:35:55 PM »

Yeah.. When I get into the thing, I will know what blower to use. I cant stand this noise. Its as loud as a Vacuum cleaner in the room.  I think my Oreck might make less noise.

Its a single 4-400. This thing was made to do Telatype 24/7 at full power. As a ham, I need half the airflow and none of the noise.

I just made a contact on it.  Kc3ol in Kansas city.  Got a good report at full power. Used headphones into the Rxer so I could hear him.

The Modulator bias control is 3/4s to get the current I need.  This scares me a bit. I think the 4-125s might be about done. I need to find a set as a spare. The Bias Rises up a bit if you get long winded.  The plate and Exciter are ROCK solid where I set them.

The Freq is super stable. It never moved off 3.8500 then entire time it was on.  The Dial on the front reads 3.750 so its off. Need to calibrate the VFO dial. 

What a neat old Transmitter. With some minor work, I think I will have a Great sounding stout old Rig!

Clark
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K5UJ
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WWW
« Reply #8 on: January 17, 2010, 12:17:13 AM »

Clark you are lucky.  I'm envious.  I hope to own a T3 some day. 

You say it takes 600 ohm balanced audio?   Because this is an issue I assume you are working with High Z unbalanced stuff.  You could put the audio gear into an isolation transformer.    I think you can just put the hot on one side of the transformer primary, the other side to ground and the secondary winding goes to the balanced input on the rig.  Try a Jensen transformer.   They make the JT 10K61 1M which is excellent for your problem.   It is 10K ohm to 600 ohm and is designed to take the unbalanced high Z output of a tube circuit and drive a 600 ohm balanced input.   You also get the RF and ground loop isolation of a transformer.   details here:  http://www.jensen-transformers.com/ln_out.html  click on the model number to get the data sheet.

Rob
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N3DRB The Derb
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« Reply #9 on: January 17, 2010, 01:05:18 AM »

sorry to hear about your buddy Clark, but glad to see the rig made it to a safe place. I hope whatever I have makes it to people that care when i croak out.

this is all you will ever need to know about mods to that txer. Do this stuff.

http://www.w1ujr.net/wa1hl_mods.htm
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N3DRB The Derb
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« Reply #10 on: January 17, 2010, 01:22:12 AM »

and maybe not enough blower, but I got 2 of these.... one from the guy at the link and I found a twin at a fester last year, so I have a matched pair now.

paid 5 bucks for the hamfest one -  but I thought the price was reasonable for a new unit off the website.  both brand new in the box. 15 cfm each.

I'm going to use them for my 4-400's.  With the SK 406's  they'll be fine.  I may buy another 2 off the website to put in stock for future needs.

http://www.ecrater.com/product.php?pid=2622984
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KX5JT
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« Reply #11 on: January 17, 2010, 01:29:36 AM »

Hey Clark,

I heard you with KC3OL tonight.  The band was mega noisy from QRN and QRM but your T-3 broke through just fine.  Just thought you'd like to know, it sounded good.  You'll get it sounding even better I know.  Nice rig.

73 KX5JT John
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ke7trp
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« Reply #12 on: January 17, 2010, 09:07:36 AM »

Thanks alot for the report.   Poeple are saying the Carbon mic sounds fine and real clear.  My hand is killing me from Gripping that damn pistol Grip mic..

I got up early to get on AM.  The T3 is working fine. Somehow, The fan noise is much less this morning. Maybe a few hours of running and then a night of cooling off, Helped the fan. Its still way to much noise for this small room though.

Thanks for the linke about the blower motors. I dont plan to mod this one or hack it up.  Just trying to run my audio rack in, Bypass filters and clipper. Thats it.

Rob.  The audio rack is outputing balanced low level, low impedance.   The T3 is balanced low level, low impedance. I should not need any transformer.

What I cant figure out, is the proper wiring for the plug.

Clark


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WA3VJB
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« Reply #13 on: January 17, 2010, 09:14:24 AM »

I just made a contact on it.  Kc3ol in Kansas city.  Got a good report at full power. Used headphones into the Rxer so I could hear him.
//
What a neat old Transmitter. With some minor work, I think I will have a Great sounding stout old Rig!

Clark

I bet that was a sweet moment, especially if you also were thinking of your friend who has passed.

Did you roll video or audio to record for your scrapbook ?

Last year I decided I was not using my T-368 often enough to warrant the floor space. I felt it really ought to be on the air with someone who would use it and had the technical creds to keep it going. 

1957 Crosley, model "C," with the rare curved-glass Marion meters all the way across. I set it up to use an external speech amp, pair of 807s  in a Bogen PA unit that I got from Derb's fix-it shoppe when he worked in Baltimore.

I'm happy to learn the T-3 has since been on the air from its new home. Haven't had a chance to work it, that will be a melancholy moment. Just like the feeling I had when I was shutting down the transmitter for the last time at my place.

http://www.youtube.com/watch?v=17le97Cj3Uc



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ke7trp
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« Reply #14 on: January 17, 2010, 09:50:15 AM »

Wow.. Mine is a BW "C" model with Brand new Marion Curved meters all across.  They look fantastic. 

Nice video! 

I did not record the moment. I did do something when I first fired it up though. I gave him a call over the air and waited a minute of silence.

Clark

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w3jn
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« Reply #15 on: January 17, 2010, 12:15:23 PM »

I have Paul's T-3 ensconced at our lake house.  Although it goes on periodic rests, it does get a workout when we're up there  Grin
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ke7trp
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« Reply #16 on: January 17, 2010, 12:54:20 PM »

I need some 4-125s if someone has a set. These are flat.  Keep having to turn Bias up higher and higher on them.

Clark
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ke7trp
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« Reply #17 on: January 17, 2010, 07:09:58 PM »

My tubes are good.  I was led to believe that this transmitter would do ALOT more power then does.  I had a guy tell me that it does 2000 watts pep.  That made sense since the rig has a 500 watt carrier.  That is not the case.  When I hook up a Heathkit watt meter, It slams the needled over hard to 2000 watts.. But if you hold a tone, It settles around 1100. 


My Plate current is spot on, My Mod resting current and my Mod peak current are spot on.  The voltages are perfect and at the books ratings.

I bypassed the two filters.  Simple job. Did not even remove the Speech amp.  I also put a Paper clip in place of the clipper like suggested.  I now have more then enough audio. I think its best to load this rig down to 375 watts and let it Ride.  Loading it up at 500 just gets you more carrier and no more audio.

Next up is to service and slow down that damn loud blower motor.

Clark
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WA1GFZ
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« Reply #18 on: January 17, 2010, 07:54:10 PM »

Monitor the output air it should be warm, not hot. A cool tube lives a long life. I suggest you check Eimac specs rather than self appointed experts. The 4-400 wants air through the socket. The 4-125, I have never seen any air specs on it. Check care and feeding. 6.5 vs 15 amps of heater current.
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ke7trp
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« Reply #19 on: January 17, 2010, 07:57:23 PM »

Keyed unit into Big Bird dummy for 15 minutes.  Cool air out the back.  Its running the same power as the GLobe king peak. THe Globe uses a small fan and no chimny. I think its ok to cut it down. if I get long winded, I will turn it up.

Clark
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N2DTS
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« Reply #20 on: January 17, 2010, 08:00:18 PM »

Are the 4-125's running AB1 or AB2?
AB1 is about 330 watts. AB2 is 400.

AB1 should be good for almost 600 watts input.
You could likely just plug in some 4-250's or 4-400's.

Brett

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ke7trp
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« Reply #21 on: January 17, 2010, 08:20:58 PM »

Its about 350 watts of audio.  I can plug in 4-250s but the Fil trans runs hot. I should change it.  I am not going any farther with this rig. I got it for sentimental reasons.  I will use it once in a while. The dual 304TL by dual 4-400s will be my HIFI machine.

Clark
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WA1GFZ
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« Reply #22 on: January 17, 2010, 09:29:59 PM »

4-250s or 4-400 in modulator overloads the transformer. I sold a pile of transformers rated for the job but all out of them now. I must have sold 20 of them. They had dual 5 VCT 25 amp windings. Maybe somebody in the N.E. still has one of those black transformers kicking around. 4-125s do the job ok.
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Steve - WB3HUZ
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« Reply #23 on: January 17, 2010, 09:31:07 PM »

Oh brother, another smug T-368 owner.
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N3DRB The Derb
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« Reply #24 on: January 17, 2010, 09:53:57 PM »

hey, you. Quit disrupting & instigating. next thing I know you'll be smug about yer smugness. I'm gonna be fresh on the scene at Richmond, see?  Roll Eyes
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