FL2100B cloudy tubes?

[357]

I picked this up yesterday and it looks pretty mint.
Nothing overheated or charred, no mods, looks barely used.

I unhooked the HV and let the tubes burn over night.
I wanted to inspect the tubes further and noticed some clouding on the glass and was curious if I have a problem.
Pictures look worse than it is but still...

 

[357]

 

[BJ radionut]

Don't look to bad...I say go for it...see what happens IMHO...give them about 50w drive and see what you get...
All the Best
Gary

 

[357]

Thanks.
I notice these are "round tops".
I have another matched set that are the beveled top and I can see that the plates are a bit bigger and beefier.
I'm waiting to borrow a variac before I fire up the HV.

 

[BJ radionut]

Those tubes were most likely made by RCA or Sylvania....
Hard to replace, so treat them nice!
Run them about 500w PEP and you'll have a good working amp for a long time.
Amp looks very clean...well taken care of, by the interior pics.
Do your self a favor...Don't use it on AM...
All the Best
Gary

 

[BJ radionut]

http://www.bcdxc.org/fl2100b_man.pdf

Good info if you did not get the manual...and some useful tube data at the end...
When reading the specs note that power is rated at INPUT not output...
so figure 50% duty cycle equals max 600w PEP output...SSB
Also rated INPUT on AM service is 600w....so max 300w PEP output...
That why I said do yourself a favor...don't use it on AM...
Enjoy All the Best
Gary

 

[357]

It was originally a Taylor T160L designed for AM modulator service in 1959 but with AM dropping rapidly in ham and commercial usage they couldnt find an OEM buyer. The BCB TX's werent Taylor users and stuck with RCA, Eimac, Westinghouse, Amperex which were well known and reliable.

United Electronics in NJ bought the design in 60-61 and called it the 572, not to be confused with the 1930's DeForest version where the 5 identified the manufacturer and the 72 was the actual type.

UE could not produce them fast enough and partnered with Cetron in IL and the 572A was UE with the round top and 572B was the shouldered glass Cetron.
You will also find some round top Cetrons which were actually built by UE when Cetron was overloaded with orders. Both private labeled for others such as GE, Raytheon, Waters, Amperex, RCA, Dentron, and maybe others.

https://www.eham.net/ehamforum/smf/index.php?topic=113259.40;wap2

Looks like I got 3 different cetrons...

 

[Captain Kilowatt]

Nice looking amp. Nothing wrong with Cetron tubes BTW. they are actually very good. Like Gary said above don't push the amp too hard and do not expect more than 600 watts pep out on SSB and you should be fine.

 

[wavrider]

https://www.w8ji.com/fl2100_problems.htm

https://pa0fri.home.xs4all.nl/Lineairs/FL2100Z/fl2100zeng.htm

Some more reading on that old amp.

 

[357]

Well since I have no hope for a variac and they are $$$ on ebay, I've been bringing the HV up with a 5K resistor via the 425V tap.
the volts were 1000 and left it that way a few minutes.
No blue glow, no arcing, no rises in temperature on the caps.
Now I moved over to the 620v tap for 1500v, still good.
Will report back.

 

[357]

well on the 850 tap now for 2100v....no smoke.

 

[357]

any advice before I pull the trigger? Nomad?

 

[357]

well before I hookup the HV for good, I'm gonna tune to input.

.....flat match, 27.000 to 28.000

 

[Captain Kilowatt]

any advice before I pull the trigger? Nomad?

Fire extinguisher handy?

 

[357]

2400v 90ma idle, some glow on 1 tube...