eHam

eHam Forums => Amplifiers => Topic started by: VE7ALQ on September 26, 2004, 10:56:07 AM



Title: 572B/T160L tubes. Country of origin?
Post by: VE7ALQ on September 26, 2004, 10:56:07 AM
I see that "RF Parts" at http://www.rfparts.com is selling 572B transmitter tubes as matched finals for both Svetlana and Taylor brands.  I know there are issues with the Svetlana 572B/T160L tubes and the Yaesu FL2100B Linear.  Are there issues with the Taylor 572B/T160L tubes and the Yaesu FL2100B Linear?  What is the country of origin of the Taylor (says made to American specs)?  I think the Svetlana 572B/T160L tubes are made in Russia, and NOT to American specifications (FL2100B oscillates).  Are the Taylor 572B/T160L tubes made in China?  Are they a drop-in replacement for my kinda soft tubes currently in my Yaesu FL2100B linear?

Note: The Taylor 572B/160L tube is cheaper than Svetlana 572B/T160L and according to RF Parts has higher gain and greater plate dissipation.


Title: 572B/T160L tubes. Country of origin?
Post by: WIRELESS on September 26, 2004, 02:11:39 PM
Would you be interested in buying Cetron 572b tubes?  If so you can buy them from Richardson Electronics under the National name.  Years ago Richardson bought Cetron, eventually Richardson rename 572s to National while Cetron continued to make them, Richardson moved Cetron manufacturing to China and still markets them as National. They are still identical to the old Cetron specs because technically, Cetron is still making them (in China).

Also, Cetron is still in business as a div. of Richardson making other electronic items. They never went out of business like all the eHam experts keep saying.


Title: 572B/T160L tubes. Country of origin?
Post by: WB2WIK on September 26, 2004, 05:46:46 PM
1.  I'd recommend you call RF Parts and ask them.  It's a free call.

2.  I'd give no credibility to people who reply without posting a callsign.

Good luck!

WB2WIK/6


Title: 572B/T160L tubes. Country of origin?
Post by: VE7ALQ on September 26, 2004, 06:00:04 PM
I did a google on "National 572B" and came up with an Australian company "Evatco" which wants A$180 each(ouch!)  I can get a PAIR of matched "Taylor" 572Bs from RF PARTS for under USD$100.

I have two E-mails outstanding at the moment.  One was sent to Yaesu to see if they recommend Taylor 572B/T160L tubes in their FL2100B Linear, and one was sent to RF Parts to see about arranging the details of an export order to Canada.  Nothing finalized.


Title: 572B/T160L tubes. Country of origin?
Post by: VE7ALQ on September 27, 2004, 04:19:01 PM
I phoned RF Parts this afternoon and placed an order for the Matched Quad of Taylor 572B/T160L  The RF Parts catalog claims that the Taylor 572B/T160L is the tube of choice for the Yaesu FL2100B Linear. No mods necessary :)

I have a pair of Svetlana 572B tubes which are surplus to my needs.  Brand new, never been used.  Wonder what I could get for them on E-BAY?


Title: 572B/T160L tubes. Country of origin?
Post by: KB1LKR on September 27, 2004, 05:21:35 PM
WB2WIK: "Wireless" is registered here as WA8KJP, and a check of the FCC database shows him to be Richard, of Michigan, holding an Advanced ticket, so he should be as good (or as bad <grin>) a source of info as anyone else w/ a callsign associated w/ their e-Ham account, though I would agree it would be easier if he used his call as his user name.

As for preferred choice of tubes and country of origin I can offer no help, so will defer to others, no doubt wiser than I.

73

de KB1LKR -- Steve


Title: 572B/T160L tubes. Country of origin?
Post by: KG6AMW on September 27, 2004, 06:15:09 PM
Last time I checked the 572B Taylor brand (a very old American name in tubes) were made in China for the RF Parts Company. I believe the Svetlana 572B is made in Russia.  Everything else is pretty much NOS (New Old Stock) with origins primarily from Europe and the USA. The Taylor tubes have a very decent track record. NOS supplies are aging and problems are developing.  

KG6AMW


Title: 572B/T160L tubes. Country of origin?
Post by: W8JI on October 07, 2004, 07:23:51 AM
The problem you are going to find is 572B's are no longer tested at enough voltage. You'll see the Chinese, probably through ignorance or a desire to have high yeilds, do not pump down and age the tubes properly nor do they test them at enough voltage.

The normal processing for tubes is to pump them down while they are very hot, and while excessive voltage with controlled current is applied. The combination of arcing and heat and pumping pulls gas out of all the materials inside the tube.

This is an expensive energy and time intense process, and is the first place cheap people cut costs. This is why Chinese tubes have such terrible problems with arcing.

As for Svetlana, all the tubes they sold were old stock that was sitting around for years. About 50% of "new" Svetlana tubes failed hypot tests, and some of those that passed failed in field use.

To the issue of stability, the problem is really in the PA design. All the cures are band-aids. The problem with 572's is the grid leads are thin and long, and the feedthrough capacitance is high. Worse yet Yaesu stupidly tried to tie a capacitor from the output of the tank back to the input of the tube and call it "neutralization". It isn't. The phase shift through a tank with a Q of about 10 or 12 is about 130 degrees or so. It varies with how the tuning and loading is set, and that also changes the feedback loss or gain. To neutralize the tube, the shift has to be 180 and the feedback voltage has to be stable.

Only a severely RF challenged engineer would use a 572B in a system where the tube requires feedback, and then add that feedback from the output of a tank back to the input. That's a horrible method Yaesu used in SOME FL2100's.

Your best bet is to just buy some tubes and take some chances. With a warranty, you can return the bad ones. Personally I'd never use a 572 in an amplifier that was not properly neutralized at anything more than 1800 volts, and I'd never rely on a Chinese tube at more than 1500 volts without weeding through tubes on a hy-pot test.

73 Tom


Title: 572B/T160L tubes. Country of origin?
Post by: N0TONE on October 08, 2004, 09:06:11 PM
Despite what one respondent said, the "National" brand tubes from Richardson are not Cetrons.  I have samples of each and they look vastly different.  In fact, the National brand appears identical to the Taylor brand from RF Parts.  I suspect both of them are supplied by Shuguang of China.

I have had no problems with Chinese 572Bs in SB-201 and FL-2100 applications, although I have had very poor luck with Svetlanas.

AM


Title: 572B/T160L tubes. Country of origin?
Post by: K0IZ on October 14, 2004, 02:03:19 PM
I have four of the Chinese 572B's in my Collins 30L1.  Work great, about 10% more output, plates run black.  No problems.  Purchased from Penta Laboratories (old-line US company), matched quad for $140.  They told me these are identical to the Chinese 572B's sold under the Taylor brand, and in fact that they sold the chinese tubes to that other firm.  

By the way, I also purchased a matched pair of Chinese 6146B's from Penta Labs for $38.  Also work great in my KWM2A.  More than original output power.  Just touched up the neutralization cap slightly.

John