[Heath] LMO rebuilding....did I mess it up?

Sun Mar 13 18:29:48 EDT 2016

Hi Guy

I would check the frequency of the LMO output with a frequency counter  
before doing anything else. It should tune from 5.5 - 5MHz plus a small overlap 
 i.e. it tunes from high to low when the SB101 tunes from low to high.

73

Bob

Bob F Burns G3OOU,  G-QRP 6907, @BobFBurns
Crystal Palace Radio & Electronics Club: _www.g3oou.co.uk_ 
(http://www.g3oou.co.uk/) 
Technical web site: www.qsl.net/g3oou  

In a message dated 13/03/2016 18:26:02 GMT Standard Time, gggdds at js-net.com 
 writes:

Glen,  and any other members of the Heathkit  listserve,

I think I have a problem, and it's not in Houston....I got  the 80 band 
tuned up on my SB-101, so I thought I'd try it on the air..I found  an 80 meter 
LSB group of hams talking ,and having tuned up the 101' into a  dummy load, 
I turned it onto the antenna and called...they came right back and  said I 
had a nice signal...no tuner...I asked "what frequency are you  showing?" 
and he came back "3900khz".   Only one problem...I was  tuned to 3691khz!!  I 
checked this again on 40 meters...same thing...when  I transmit a signal 
using my Elecraft K2 on 7400khz, the 101' is reading (and  receiving) it on 
7181khz...Did I do something wrong with the LMO?  I  checked it's range of 
movement,and with the tuning unit dialed all the way  counterclockwise, the  
variable cap is almost closed; then, five turns to  the right and the cap is 
fully opened, as I recall.  I didn't check it on  any other bands, but at the 
moment, it would seem the LMO's output is 219khz  too low....right?   It's 
reading 219khz low exactly on both bands.....  Help....

A bit of history.  I know virtually nothing about the  history of this 
101'....I bought this one, with another 101' and two HP23  series power supplies 
from a nearby ham for $100.  He had bought them  from another ham, hoping 
to get one working one out of the pair.  He  never had time to delve into 
either of them....

Guy
WA6OQQ,
On of  the hams at Heath

On 2/1/2016 1:40 PM, Glen Zook wrote:

The LMO can be removed without removing  the front panel.  You do have to 
loosen the setscrew on the dial  assembly, unsolder the wires to the LMO, and 
remove the 4-nuts on the  underside of the chassis.

Remove the main tuning knob and loosen  the large nut on the panel that 
holds the shaft.  Move the shaft so  that the slip drive is removed from the 
dial.  Then, lift the LMO from  the chassis and away from the dial.
_

After making the repairs, put  the LMO back in place and reverse the 
directions.

Glen,  K9STH 

Website: 

_ (http://www.qsl.net/g3oou) _http://k9sth.net_ (http://k9sth.net/)  
(http://www.qsl.net/g3oou) 

____________________________________
 From: Guy Giacopuzzi 

_<gggdds at js-net.com>_ (mailto:gggdds at js-net.com) _
To: Glen Zook _ (http://www.qsl.net/g3oou) _<gzook at yahoo.com>_ 
(mailto:gzook at yahoo.com) _ 
Sent: Monday, February 1, 2016 2:22  PM
Subject: Re: LMO  rebuilding....
_ (http://www.qsl.net/g3oou) 

Glen,
Thanks for your  help....I followed some of your advice, and the advice 
that I didn't follow  came back to bite me.....I acquired a couple of SB-101's 
for a song (well, a  song plus $100, but it included two power 
supplies....)....and I've been  "bringing the 1st one 'back'" so to say....cleaning, 
checking, going thru  the tune up routine, etc......I rebuilt the LMO on an 
SB-101....removed the  front panel, etc to get to it...had to do a lot of 
general cleaning as the  entire dial assy was all gummed up.   I took apart and 
cleaned the  LMO...lubed it, removed and cleaned the stops, but I didn't do 
the braid  thing......I used a high end light oil for the lube...from 
Kroil....I  got it on the air last night, loaded it into a 75 ft long wire w/ no 
tuner  and joined a group at about 3800kc or so but they kept reporting I was  
"jumping all over the place"...as I listened, I heard them, but the  
frequency kept changing...or "warbling" as you say. My signal was plenty  powerful, 
and the group was spread out all over the California coast up past  San 
Francisco...so the 6146B's were really kicking, so to say.  So, I  reread your 
email and this time, downloaded the file on LMO  rebuilding.  I'm going to 
attempt removal of the LMO w/o removing the  front panel--can I do that?  
Maybe I'll have to remove the  "escutcheon"  to set the dial on right...Anyway, 
now I think I've got  to do the braid....I was going to use a bit of 
"soldering" or maybe I should  say "de-soldering" braid...Is that ok?   Anyway, I 
should have  followed all of your advice, not just some of it.  One other  
interesting thing....when I tuned in the stations, my RF gain control didn't  
work, and when I looked at it, the diode on the middle terminal had let  
go...but wow, did the receiver have a lot of gain.  When I  hooked it back up, 
the gain seemed to back down a bit.  I thought I'd  play with that just a 
bit to see if the control is somehow hurting the  overall receiver gain...

--  

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