LMO Question

[Bob Krassa]

At suggestion of Lynn Baustian, here are the replies to my question about the older LMO in my SB-102 that did not go directly to the entire list:

 

Doug, W4DAS, wrote:
"That is an LMO from an SB-100 or SB-101.  It is definitely not from an HW-101.  If it is wired correctly - as in an SB-101 - it should work OK.  My guess is that your SB-102 had a bad LMO sometime in the past and it got replaced with an LMO from an SB-101.  I don't think Heathkit would have done the mod as the solid-state LMO was a major marketing point on the SB-102."

 

Bob  W6VY wrote:

"The LMO on the SB series is totally different from the VFO on the HW-101.  The part number on the 301 and 401's that I have are 110-40.  The 6BZ6 is a good tube - they used several types in the different versions.  I have never had a 100 series transceiver but I think all of the LMO's from the SB series tube type radios are interchangeable."

 

Ken W7EKB wrote:

"AFAIK, the LMO in the HW-101 series is NOT interchangeable with those in the SB series. However, the last LMO that was used in the SB-102 was solid-state, whereas all the earlier ones were tube type.  This might give you a clue, but other than what I said above, I don't know the answer. I do have an SB-102 here. I suppose  I should go take a closer look at it someday..."

 

Jan, N8LQR wrote:
"First, you can't compare the SB series transceivers to the HW series!  The SB used a factory built LMO supplied by several vendors whereas in the HW series you built the VFO yourself--totally different. Looks like somebody replaced the original solid state LMO 
(Part no. 110-48) in your SB-102 with a very old tube type LMO from an SB-100.  The 110-32 LMO which you said had the
number 2736626C on it was built by TRW (indicated by their number 273).  The 66 stands for 1966 and the 26 is the 26th
week of 1966.  The 6BZ6 tube is the correct tube for this LMO.  The SB-101 used a 110-40 LMO with a 6CB6 tube.  Glenn
Zook said that the filament currents were different for these two types.  I have not checked.  Your SB-102 was definitely NOT built that way by Heath Co.  Heath never made substitutions like that!  If Heath did not have the correct parts for a product they put production on
hold until the correct parts came in.  I worked there for 23 years.  I am positive that the Heath factory service dept. also did not make such a substitution. They were not allowed." 

 

Finally, I compiled the following little table from the replies, other messages on the archives of this list and some manuals that I found on BAMA (I alone am responsible for any errors in this table which is certainly not field checked!)

 HW-100        Part No:  ?                      FET oscillator with 6AU6 as VFO amp.

HW-101                        ?                      FET oscillator with 6AU6 as VFO amp

SB-100                         110-32             6BZ6

SB-101                        110-40             6CB6

SB-102                        110-48             Transistors

SB-110                        110-28             6BZ6

SB-300                        110-13             6AU6

SB-301                        110-40             6BZ6

SB-310                        ?                      6CB6

SB-400                        110-13             6AU6

SB-401                        110-32             6BZ6

SB-640                        ?            ?

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