Warning: Creating default object from empty value in /homepages/11/d132647312/htdocs/Amfone/mkportal/include/SMF/smf_out.php on line 47
SX-101 Mark III Black Beauty replacement




 
The AM Forum
May 26, 2018, 03:51:04 PM *
Welcome, Guest. Please login or register.

Login with username, password and session length
 
   Home   Help Calendar Links Staff List Gallery Login Register  
Pages: [1]   Go Down
  Print  
Author Topic: SX-101 Mark III Black Beauty replacement  (Read 2303 times)
0 Members and 1 Guest are viewing this topic.
WA2ROC
Contributing
Member
*
Offline Offline

Posts: 287


« on: June 09, 2015, 07:17:49 AM »

Round 2 of updates:

There are a bunch of "Black Beauty" caps (BTW, they're not that beautiful, are they?) and several pinkish red caps that are of the paper and wax variety that everyone says to replace.  Well, I ordered replacements for all of them, using polystyrene metal film replacements of the same working voltage, from Digikey.  Using my company discount, they cost me about $13.00 for 24 caps, including free shipping.

Here's a few pictures of the before and after.  There are still a few BB's left but none in bad condition like some of the ones in the pictures.

( Can anyone see these pictures?  I can't.  Just a lot of garbled text)


* IMG_1895.JPG (451.79 KB, 1600x1200 - viewed 332 times.)

* IMG_1897.JPG (391.05 KB, 1600x1200 - viewed 259 times.)

* IMG_1898.JPG (242.96 KB, 1600x1200 - viewed 260 times.)
Logged

Dick Pettit WA2ROC 
Vintage Heathkit Equipment
If You Cannot Stand Behind Our Troops, Please Feel Free To Stand In Front Of Them!
K9DXL
Member

Offline Offline

Posts: 145


« Reply #1 on: June 09, 2015, 10:07:20 AM »

Yep, just garbled text.  I recapped my '101 Mk III a few months ago, and saw a huge improvement!  Now it hears really well and sounds great, too!  Hope you're as pleased with your receiver as I am with mine.
73,
Jim
Logged

Breathing solder fumes since 1959.  That explains a lot.
WA2ROC
Contributing
Member
*
Offline Offline

Posts: 287


« Reply #2 on: June 09, 2015, 01:49:38 PM »

Yes, the higher bands seemed to wake up quite a bit.

As for garbled text, I looked at other photos that were posted earlier and they too were just garbled text.

I like my 101, but it is a bit on the heavy side.  I thought my Mohawk was overweight!
Logged

Dick Pettit WA2ROC 
Vintage Heathkit Equipment
If You Cannot Stand Behind Our Troops, Please Feel Free To Stand In Front Of Them!
K9DXL
Member

Offline Offline

Posts: 145


« Reply #3 on: June 09, 2015, 03:28:29 PM »

Hallicrafters didn't call it "The Heavyweight Champion" for nothing.  On the other hand, working on radios like this save me the cost of a gym membership.
73,
Jim
Logged

Breathing solder fumes since 1959.  That explains a lot.
N8CMQ
N8CMQ
Member

Offline Offline

Posts: 11



« Reply #4 on: October 07, 2015, 11:55:29 PM »

I hope you replace all of the paper caps.

I had to replace the caps and resistors in my SX-101, as everything was stressed and
out of tolerance. I even had carbon tracked tube sockets, so I replaced them all.

The first picture is of the local oscillator, and the second is some of the work performed
so far. Notice the carbon mess around the local oscillator, and that is after cleaning!


* IMG_0669.JPG (1019.18 KB, 2052x1532 - viewed 242 times.)

* IMG_0681.JPG (1074.89 KB, 2052x1532 - viewed 240 times.)
Logged

Jeff Young
WA2SQQ
Contributing
Member
*
Offline Offline

Posts: 512


« Reply #5 on: October 08, 2015, 08:26:49 AM »

All the photos look fine here. What brand caps were they? I'm going to need to do this same this winter.
Logged
N8ETQ
Member

Offline Offline

Posts: 781


Mort


« Reply #6 on: October 08, 2015, 12:32:43 PM »



    Pix fine here too. The group of 3 BB's are all oil covered,
There cracked and leaking. Assuming each of your 24 caps is
passing 1 or 2 mA just think of the extra load on the power
xfmr.  Of course if one of them is "Re-Biasing" a tube, The
sky is the limit.

    It HAS to be done! Glad your doing it.

GL

73

/Dan



Logged
n1ps
Contributing
Member
*
Offline Offline

Posts: 268


Zorch!


« Reply #7 on: October 10, 2015, 08:07:35 PM »

Another thought on the recap process....make sure to check the IF/RF screen resistors.  The voltage on the screens affects the gain of the stages.  Its rare that I dont find a couple way out of tolerance.  Then make sure to do a tune-up and repeak the IF stages. 

A couple other known issues with these vintage receivers:
1. Check that the gain control actually goes to zero ohms.  Frequently the pot is still above ground with the pot fully CW.  This reduces RX gain.
2. Check the AVC resistor chain.  These resistors, like the others...all carbons...tend to go higher in value over time.  The effect can result in front end overload with strong signals.
3. Check the limiter switch for leakage.  A common problem.  The effect is the limiter is not completely bypassed and is partially on. 

Just some passing thoughts on a cool Saturday night.

Peter
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
 AMfone 2001-2015
Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Page created in 0.037 seconds with 19 queries.