SP-600 Northern Radio  Northern s/n 1147, Hammarlund no. 54716519

Arrived 2PM Wed., March 18, 2003

 Box, as arrived, top tape has been cut before pix taken.  Note crushed in top edges, punctures.  Some peanuts have escaped.

Opened, peanuts have settled, some had come out, but not enough to cause this large a void.

Peanuts removed to view top.  The front panel is toward the top in the left pic.  Radio has top cover which helped keep peanuts from totally filling the radio and settling too much.  Note the peanut fragments.  Many had been broken up.

More peanuts removed, showing damage to right hand side of front panel.  Radio had settled through the peanuts to contact the bottom of the box, and moved to the side to allow panel to punch thru the box.

Black plastic bag did not completely enclose the radio, allowing peanuts to "invade."  More pix of panel damage, and rt side bezel damage.

 Top, after cover had been removed.  Will be digging peanuts out with tweezers for some time.

 Back side, showing damage to rear lip of chassis.

 Bottom, with cover on, showing more damage to cover and chassis.

Bottom cover removed, peanut fragments have invaded. Bends in chassis are easily seen.

General initial observations:
    All tubes, shields and hold-downs are in place.  3 allen wrenches are in their clips.  There is a 90deg. twinax fitting on the antenna jack.  There is a fuse cover and 2 spare fuses.  There is some bending on the right side panel, at the bottom, besides the damage noted earlier.  The right side bezel is damaged and the glass is missing.  All knobs are good, clean, shiny.  The front panel shows some discoloration possibly from nicotine, should clan up OK.  It appears to have a satin finish, not gloss.  The lettering is silk-screened, not engraved.  1 dial lamp is broken.  The S-meter is not resting on zero.  Disc ceramic capacitors are evident under the chassis, perhaps there are no "black beauties of death."  The electrolytic filter cap has a date of 1-67.  

4/8/03:
  I have spent a little time on the rcvr on cleanup & straightening the bent areas, plus general listening to ck it out.  The meter is not working, it's open internally.  I got into it, and it appears that the "bobbin" is open, or not making connection to the internal leads.  It's beyond my capability to go farther with it.  I can give you a couple of references to meter repair shops that may be able to fix it.  I think it's not an uncommon problem, I've seen several people asking for replacements (with little success), and I need one for one of mine which has a poor substitute replacement.
    It's a very clean unit, the nicest I've seen.  Unless you say otherwise, I will put a 3-wire line cord on it, and change the pwr xfmr line voltage tap to reduce the output voltage slightly, since most AC service now runs over 120v vs the 110-115 back when it was made (early 1967).

4/23/03, some of the work done:

1.  Clean, polish where applicable, wax the panel & knobs.  Straighten panel bends & side of chassis bends.  To straighten the bends on the back bottom lip of the chassis would require temporary removal of many of the hardware items on it.  I can do that if you wish, but I don't think it is objectionable as is.  It did straighten a little as is.
2.  Chg tap on pwr xfmr.  Check ESR on filter cap.  All sections check very good, and probably will last a long time.  If it was mine I wouldn't replace it, because I could do it any time it might be needed.  I haven't always replaced them, have 2 or 3 out that are used regularly with no problems.  I can put discrete caps in there if you'd like.  Checked Hivoltage readings at start & after warmup.  All within a few % of spec.
3.  Clean & DeOxit all pins in turret, clean everything above chassis.
4.  Install 3-wire AC line cord and modify the wiring at the fuse to be safer.
5.  Test all tubes (exc. diodes).  One 6BE6 tested low for both sections, replaced with new one.  All tubes were original, all had Hammarlund name on them (except the ones installed as replacements by Northern).  Perform complete IF & RF alignment.
    Dial calibration came out very good on 2 bands, 3-7mc & .54-1.3mc.  The "span" couldn't be set properly on the remaining bands, e.g. with 32mc set correctly, the actual 50mc signal is recd at 50.4 with the adjustment at it's limit.  Similarly with 7mc properly set, 14mc indicates about 14.3.
    The other bands are off lesser amounts.  This may be due to the installation of 6J6 tubes in place of the original 6C4's by Northern, they have slightly different internal capacitances.  Usually SP-600's can be made to track exactly at the endpoints and fall in very well at all points in between.  If you want it better, I can add a small fixed cap, about 2 to 5 pf, across the trimmer cap for the band in question, then try it to see if it comes in.  Some of the bands have about a 2 -8 pf variable, some abt 8 - 25 pf.  It's at it's maximum and can't get what's needed, so adding a bit might do the job.  I'll give it a try one one band if you'd like, probably the 7-15mc would be the most used for SW listening.
    That's abt all I can think of telling you at the moment, I'm probably leaving something out, but that's what I've got notes on.
--

4/25/03:
    I will replace your filter caps, it's good insurance, under $20 I think.  I may give the range problem a quick try on one band.  If it works, fine, if not I'll take it out.  I can make you a logging chart every mc or 2 to help bandcruising if needed.

5/7/03:

panel & knobs cleaned, new rt side bezel & glass installed

underneath, overall & closeups of new line cord installation, with wiring slightly revised to put the fuse first in line, and new 20mf @ 450vdc filter capacitors installed (much smaller than the original 3 in 1 can).

5/12/03
    I have replaced the filter cap with discrete ones, much smaller.  I was incorrect about the possible range "fix", the alignment caps are at minimum on the problem bands, adding small additional caps will go the wrong way.  It's not easy to reduce capacitance, so I will leave it as is.  I have made a calibration chart, shown below:    (an * indicates the actual dial reading is within one division of being correct.)

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This page last updated on 02/15/2004.