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Restoring Heathkit sb301 and 401, Really need some advise!

Discussion in '"Boat Anchor" & Classic Equipment' started by KB4MNG, Feb 7, 2012.

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  1. KB4MNG

    KB4MNG Ham Member QRZ Page

    I have started cleaning the 401 and noticed a line of crystal on top of the deck. Does that mean the a 401 has the optional crystal pack? No cables came with the unit so I have to make my own. I was going to use regular wire. Will that be ok or will I have to use rg 62?

    Thanks kb4mng
  2. KK4CWA

    KK4CWA Ham Member QRZ Page

    Anyone have a decent 401 for sale I have a sb300 and wish to fix up a 401 to match my 301 I am rebuilding. I have the crystal pack and filter and tubes.
  3. AF6LJ

    AF6LJ Ham Member QRZ Page

    Yes it has the capability of operating independent of aSB-300/301.
    Talk to Glen about interconnect cables. they are good to have and he makes them out of the proper type of coax. Those cables that connect the LMO, BFO and Het. Osc. are made from 93 ohm coax and they are short to prevent loading down the circuits.
  4. K9STH

    K9STH Ham Member QRZ Page

    Couple of things:

    First of all, I have posted the "warbling" cure for the Heath SB-Line LMOs:

    Finding decent RG62/U coaxial cable is getting hard these days. You can use RG59/U for the LMO, HFO, and BFO cables. RG58/U is "iffy"! However, do NOT exceed 24 inches for those 3-cables. The antenna connection between the SB-401 and SB-301 is RG58/U and can be any convenient length. The other cables are just shielded cable and can be any convenient lengths.

    I have had to go to RG59/U for the cables that I make instead of RG62/U since getting reasonable lengths of that cable is getting hard and the quality of what is "out there" is pretty suspect! The cable kits that I sell have the 3-oscillator cables 24 inches long and the rest 30 inches long per Heath's recommendations. However, the only critical cables are the oscillator cables.

    Here is the URL for the cable kits. However, I don't like to take advantage of Fred by "advertising" on the site.


    There is NOT an extra filter for the SB-401. The only filter in the rig is the 2.1 kHz SSB filter. For CW the carrier is not "shifted" to one side or the other of the filter passband which help attenuate the carrier on SSB but goes directly through the center of the filter and is not attenuated. That is why there is a separate CW BFO crystal in the SB-401. The CW BFO crystal is on the center of the passband of the 2.1 kHz filter. Collins, in the 32S-3 and 32S-3A, doesn't use a separate BFO crystal for CW. It uses the USB BFO crystal. However, in those transmitters the 2.1 kHz SSB filter is bypassed instead of operating "straight through" like in the Heath SB-Line.

    Glen, K9STH
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