SB200 - general questions

[Army Curtis - AE5P]

It appears from the pictures that the coils in question are part of the
filament circuit for the 572B's. With the relatively small size of wire
used, I believe the purpose was to drop the filament voltage a little bit on
the tubes. It might be interesting to closely measure the voltage actually
getting to the filaments, both with the coil jumpers and the short jumpers
you substituted. You may find the short jumpers result in the voltage being
a little too high. 

Hope this helps.

Army Curtis - AE5P
Nacogdoches, the oldest town in Texas

-----Original Message-----
From: Heathkit Owners and Collectors List [mailto:HEATH at LISTSERV.TEMPE.GOV]
On Behalf Of Tom Buchanan
Sent: Friday, March 14, 2008 3:08 PM
To: HEATH at LISTSERV.TEMPE.GOV
Subject: SB200 - general questions

I have a SB-200 I recently refurbished with the Harbach mods and several new
parts.  It has new caps and 2450 HV with idling plate current of 60 ma which
is a little low.    I get full output on CW (500w) & SSB (600-700w) on 20 to
80 meters.  Low output on 10 meters SSB of 250w max.

 

What is the best 572B replacement tube to use?  Would tweaking the 10 meter
coil or checking the parasitic resistors help the low output on 10 meters?

 

A 10 uH RF choke attaches to the lugs on terminal strip "M" on the back of
the chassis under the final output tubes.  It is supposed to have a 2 lug
terminal strip, but someone installed a 4 lug in the past.  There are little
coils of small wires to connect lugs 1 & 3 and 2 & 4.  It looks like a
jumper wire would do the same thing.  Anyone know what the purpose of the
coils would be? I have a picture of the amp with the jumper wires at
http://scrtc.com/~tlbuch/Vintage%20Heathkit%20Ham%20Radio%20Equipment.html

 

 

Thanks & 73,

 

Tom

KG4KGY

 

 

 

 

 

 


-----------------------------------------------------------
Products bought, sold or traded here is the responsibility of the
parties involved.  This list and the City of Tempe are not responsible
for losses or misrepresentations of any kind.  Buyer beware!

-----------------------------------------------------------
This list is a public service of the City of Tempe, Arizona
-----------------------------------------------------------

Subscription control - http://www.tempe.gov/lists/control.aspx?list=HEATH
To post - HEATH at LISTSERV.TEMPE.GOV
Archives - http://listserv.tempe.gov/archives/HEATH.html

No virus found in this incoming message.
Checked by AVG. 
Version: 7.5.519 / Virus Database: 269.21.7/1328 - Release Date: 3/13/2008
11:31 AM

No virus found in this outgoing message.
Checked by AVG. 
Version: 7.5.519 / Virus Database: 269.21.7/1328 - Release Date: 3/13/2008
11:31 AM
 

-----------------------------------------------------------
Products bought, sold or traded here is the responsibility of the
parties involved.  This list and the City of Tempe are not responsible
for losses or misrepresentations of any kind.  Buyer beware!

-----------------------------------------------------------
This list is a public service of the City of Tempe, Arizona
-----------------------------------------------------------

Subscription control - http://www.tempe.gov/lists/control.aspx?list=HEATH
To post - HEATH at LISTSERV.TEMPE.GOV
Archives - http://listserv.tempe.gov/archives/HEATH.html