Replacing tubes -Tram D-201a

[husker]

Hi folks, I am having an issue I know is my own fault, brought it on myself due to not knowing any better, but now how do I fix it???

I bought a wonderfuly beautiful D-201a a few years back, dead key was about 3.6 watts or so per the radio meter. Thinking it must need new tubes, because it just must..I bought all new tubes and one by one replaced them all....that's all I did. Doing nothing else no neutralization etc.. So now I am lucky to get .5 watts and very low modulation. Every else still works perfect and I have kept this radio spotless etc. I als have 1 more 201A and 2 201's plus three boxes of tram parts...but I am NOT a tech and I have learned my leasson.

What can I do to save this beautiful piece of history?? I look forward to any and all help/comments.

thanks

[**GRUMPY**]

Sounds like the Final Amplifier needs reneutralition. I'm no tech by any means so this is just my guess, there are plenty of techs on this forum that will be able to help you for sure.

Check this out if you already haven't, maybe it will help you!

cbtricks.com/radios/tram/d201a/graphics/tram_d201a_om_pg30_pg48.pdf

Good luck and I am sure you will get better help on here than I can give you

[Sandbagger]

Jul 1, 2008 0:19:31 GMT -5 husker said:

Hi folks, I am having an issue I know is my own fault, brought it on myself due to not knowing any better, but now how do I fix it???

I bought a wonderfuly beautiful D-201a a few years back, dead key was about 3.6 watts or so per the radio meter. Thinking it must need new tubes, because it just must..I bought all new tubes and one by one replaced them all....that's all I did. Doing nothing else no neutralization etc.. So now I am lucky to get .5 watts and very low modulation. Every else still works perfect and I have kept this radio spotless etc. I als have 1 more 201A and 2 201's plus three boxes of tram parts...but I am NOT a tech and I have learned my leasson.

What can I do to save this beautiful piece of history?? I look forward to any and all help/comments.

thanks

Well, you can start by putting back the old tubes and seeing if it works again.

If it does, it's possible that the "new" tubes you got were not all that good. Also, if they are Russian tubes, they sometimes do not perform as well in certain cases. Also make sure you didn't accidently put the wrong tubes in the sockets. Also, the newer D201's can have socket issues. make sure the pins fit tightly in the sockets. I've slightly "fanned" out the bottom half of the tube pins (on the smaller tubes), and that seems to make a little better contact. The only real cure is to replace the sockets, but that's a bit of a chore.

There are only 2 tubes that are responsible for transmit carrier power, and those are the 12BY7 driver and (one of) the 6L6 output tube. It shouldn't take long to figure out which tube is not doing its job.

It's possible that the radio might respond to an alignment, but a drastic drop in power like that is most likely more involved than a simple alignment. But you could try peaking the final load and plate tune caps in the back of the radio (under a plate on the 201A).

[husker]

Funny,
I went back in amd re-seated all the tubes and BA brd etc.. dead key 4.5 watts...not sure what it was, but I am going to leave it alone for now!

[2600]

A tube tester is valuable to weed out "new" tubes that are no good.

Russky tubes are not all bad. Military-grade types are best.

I won't put a new tube in a radio before the tester says it's okay. Saves a lot of wasted time.

Changing just one tube that has two tuning adjustments hooked to it can throw the "peak" setting of both those tuning slugs off of their "peak" adjustment.

Might not see much difference when only two tuning slugs are now "off" their peak settings.

But when you change all the tubes, this happens to EVERY tuning adjustment in the radio, and the performance usually suffers. But this is a random influence. A replacement tube made on the same assembly line as the original may not disturb any adjustments at all. It's those small mechanical differences between brands that cause the radio's adjustments to be affected by changing a tube. The hard part is to predict whether or not the new tube will work better, or as well as the one you replace, or if it will affect the alignment at all.

It really sounds as if one or more tube sockets is getting "loose". The spring contacts in those sockets will lose their spring temper and go slack after the first few years of regular use. If you feel little or no friction when pulling a tube from its socket, this is a clue. Sometimes a solder connection under a socket will develop a crack. But if 'rocking' a tube gently in the socket gets you crackle noises, or the signal drops out, that socket is going to cause spontaneous trouble some time later on. Cleaning it with a non-residue solvent may help. But if that socket is loose, it will only help for a while.

A "tap" with one finger on the side of the receiver tubes can reveal internal noise problem in a tube that tests okay.

73

[husker]

Makes sense, I will go through this Tram and see if I can get one to act up. I do need a tester, but I *ASSUME* ( I know I shouldn't ever do this!!) the Tubes I got from Randy's are all good. I actually bought 4 complete sets and I have another 8 8950's for anold Eagle 515 amp. This radio is in beautiful condition for it's age, and I really tend to do everything I can to keep it that way. I have a TON of old Tram parts I got from a guy getting out of the business..alot of dials, BA brds( some good, some needing re-build) main brds, etc..

I don't use this radio that much, but I do power it up and let it run for a while to keep the caps clean so to speak..

thanks!

[husker]

On the other D201A I have the AM audio is bad. The SSB audio is wonderful. So I followed the manual and replaced V400 and V401, but nothing changed. Anyone know if this is something I can fix or do I need to find a tech....

thanks