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

donate to eham
   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: 2KDClassic consult or service at Dayton?  (Read 1812 times)
WA8FOZ
Member

Posts: 203




Ignore
« on: May 12, 2008, 02:30:26 PM »

After 35 years of faithful service, my venerable 2KD-Classic is doing some very strange things. I am already in contact with Henry Radio, in hope of reaching a solution (and not having to ship this thing!). So far, we're stuck. Before starting another thread here, I wonder: is anybody coming to Dayton who services these babies? I live nearby and could even cart the thing up, if that were necessary...

73, Bill WA8FOZ
Logged
W1QJ
Member

Posts: 2983




Ignore
« Reply #1 on: May 13, 2008, 05:08:10 AM »

Hi Bill, I reapir all sorts of amplifiers.  Why don't you throw out your problem here and see what the consensus is.  We can also talk at Dayton but it would be nice to have you make a few checks before hand.  What are the symptoms?  Lou
Logged
WA8FOZ
Member

Posts: 203




Ignore
« Reply #2 on: May 13, 2008, 03:17:57 PM »

Hello Lou:

Thanks for your interest. Here's the story:

1) I noticed a bit of hum on CW and AM carriers. None at all on SSB. So I replaced the electrolytic caps - had done so about 10-12 years ago without incident.

2) While I was removing the filter cap board, I broke a wire. It was a red-and-white wire running from R112, a 10kohm resistor. After consulting with Ted S. Henry, I (re)soldered it to R109, a 25 ohm resistor.

3) When I returned the amp to service, I noticed three things:
a) The hum was still there - and again, not on SSB - no visible AC wave on SSB idle
b) My HV, as measured on the meter at idle, was down from 3200 to ~3000 volts - but the power output was as good as ever.
3) When I transmit, the HV indication on the meter goes down, WAY down to a NEGATIVE voltage, pinning the meter against the zero peg! As near as I can tell, the HV itself remains up, since my output is fine. But the meter reads negative. A very small amount of drive will produce a partial deflection, and the downward deflection varies on SSB - like an ALC reading. More than about 10 watts input pins the meter back!
So what did I do?
73,
Bill
Logged
KA5N
Member

Posts: 4380




Ignore
« Reply #3 on: May 14, 2008, 11:44:29 AM »

I suggest that since the broken wire was in the HV metering circuit, there is some bad component or bad connection in this circuit.  R112 is connected to R109,R119,D107,D105 and D106 one one end and to R111 and a switch on the other.
Allen
Logged
WA8FOZ
Member

Posts: 203




Ignore
« Reply #4 on: May 15, 2008, 08:18:12 PM »

Thanks. I was hoping for a magic fix, but I know better!
Logged
Pages: [1]   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!