Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1] 2 Next   Go Down
  Print  
Author Topic: 3-500z  (Read 9755 times)
EI5GUB
Member

Posts: 52




Ignore
« on: November 11, 2013, 02:27:49 PM »

Hi Im thinking of changing the valves in my Heathkit SB-220,what are the best 3-500z valves now,my watt meter is showing around 700 to 800 watts ,can I expect much more with new valves.
Logged
AH6RR
Member

Posts: 803




Ignore
« Reply #1 on: November 11, 2013, 03:57:31 PM »

RF Parts in the USA has a good track record on new 3-500ZG's plus a good warranty. There might be distributors in EU that offer Taylor or Greenstone tubes since you are there it might be better to buy local.
Logged
W8VVE
Member

Posts: 188




Ignore
« Reply #2 on: November 12, 2013, 05:47:37 AM »

RF Concepts (Alpha amps) sells a matched pair of them for $278 plus shipping. 
Here is the website...73...Sam W8VVE
http://www.rfconcepts.com/PRODUCTS/tubes/3-500ZG-Tube-Glass-Triode-Graphite-Anode-Matched-Pair
Logged
K8AXW
Member

Posts: 3777




Ignore
« Reply #3 on: November 12, 2013, 08:14:30 AM »

Quote
can I expect much more with new valves.

With a good pair of 3-500Zs you should get an output of around 1200W.  However, with that being said, note that if you're line voltage is down even a few volts, your output will also be down.

You might consider that when you see a lower than normal power output.

I'm assuming that the drive power hasn't changed.


Al - K8AXW
Logged
EI5GUB
Member

Posts: 52




Ignore
« Reply #4 on: November 12, 2013, 02:19:43 PM »

hi thanks for all replies,the plate voltage is 2500 and has never changed in all the time Ive had this amp,what is the difference between 3-500z and 3-500zg
Logged
G3RZP
Member

Posts: 4501




Ignore
« Reply #5 on: November 12, 2013, 02:23:34 PM »

As I understand it, the ZG has a graphite anode
Logged
AH6RR
Member

Posts: 803




Ignore
« Reply #6 on: November 12, 2013, 02:34:43 PM »

hi thanks for all replies,the plate voltage is 2500 and has never changed in all the time Ive had this amp,what is the difference between 3-500z and 3-500zg

The SB-220 should have 3000V on the plate in the SSB position and 2500+/- in the CW position so if yours is showing 2500V in the SSB position then there would be 2 things going on #1 the metering resistors have changed value(most likely) or #2 there is a problem with the HV section though be it small but still a problem and at 2500V you would see 800-900W out so the tubes would still be good. If the HV has changed recently then the HV section needs looking at. The difference between the 3-500Z and the 3-500ZG is the ZG has a graphite anode and the Z has a metal anode. 
Logged
EI5GUB
Member

Posts: 52




Ignore
« Reply #7 on: November 14, 2013, 04:19:34 AM »

hi again,the metre is showing 2300 volts ssb and 200 cw so its down a bit so,perhaps valves are fine
Logged
W8GP
Member

Posts: 199




Ignore
« Reply #8 on: November 14, 2013, 04:34:13 AM »

It's also possible that the voltage is OK and the resistors for the voltmeter have changed value.
Logged
W8JX
Member

Posts: 5688




Ignore
« Reply #9 on: November 14, 2013, 04:52:59 AM »

It's also possible that the voltage is OK and the resistors for the voltmeter have changed value.

True but point is 3-500z's like 3000 and more on plates for better output and gain and if your supply is soft your output may be down because of that and not tubes.
Logged

--------------------------------------
All posted wireless using Win 8.1 RT, a Android tablet using 4G/LTE/WiFi or Sprint Note 3.
AD4U
Member

Posts: 2158




Ignore
« Reply #10 on: November 14, 2013, 05:45:47 AM »

If your SB-220 has EIMAC tubes, even if they are the original ones, they are probably still OK unless they were abused or used A LOT by a previous owner.  My SB-220 and my L4B are still running the original EIMAC 3-500 tubes and after 40 years they still put out the same power they did when new.

The SB-220 should have HV around 3000-3200V.  If yours only has 2500V, something is wrong.

Dick  AD4u
Logged
EI5GUB
Member

Posts: 52




Ignore
« Reply #11 on: November 14, 2013, 11:34:08 AM »

hi yes it has Eimac valves for sure and doesnt get alot of abuse by me or last owner,i fitted a bigger faster fan in it to cool the jugs down,no point changing valves so,no much I can do with power supply either
Logged
WB2WIK
Member

Posts: 20575




Ignore
« Reply #12 on: November 14, 2013, 01:39:08 PM »

I think you have 230V, 50 Hz power there.

Not so sure the SB-220 transformer is rated to operate at 50 Hz, and you may be taking a bit of a "hit" there in efficiency.
Logged
K8AXW
Member

Posts: 3777




Ignore
« Reply #13 on: November 14, 2013, 07:25:34 PM »

GUB:  My 3-500Zs (Eimac) are 30 years old and still putting out full power.  My plate voltage is 33-3400V.  My plate current runs over 700ma.  When my line voltage drops to below 235VAC then my output drops to 1KW or lower.

Al-K8AXW

Logged
EI5GUB
Member

Posts: 52




Ignore
« Reply #14 on: November 15, 2013, 01:21:44 PM »

sorry for delay I have a bad flu etc,yes we have 220 volts here and 50 hz,maybe i will just do with what i have power wise
Logged
Pages: [1] 2 Next   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!