610C-3 MONITOR SCOPE





The Heathkit Model SB-610 Monitor Scope was first introduced in a kit form By Benton Harbor during the late 1960s and sold up until the early 1970s. It replaced the previous older model HO-10 scope. The SB-610 was used to display transmit signal patterns, RF envelope, RF trapezoid, or RTTY cross patterns for transmitters with outputs up to 1000 watts. These wave patterns greatly assisted the operator in the proper tuning of his transmitter.The Monitor Scope would also display receive signals from other stations when wired for the correct Intermediate Frequency ( IF ) of the accompaning receiver. The majority of the scopes were constructed for the high-end ( 3000kc to 6000kc ) IF which was standard for Heathkit receivers. Three IF CANs were included within the original kit. The kit was also able to be wired for low and middle range IFs, to accompany other manufacturer's equipment by the use of various IF CANs and their accompaning components. Upon completion of a scope kit most builders nornally discarded the other two IF CANs. The 455kc IF which is used by Collins equipment, is extremely rare to find at the present time. The scope covers frequencies between 160 to 6 meters.

Over the past thirty years due to age and heat factors, components in the majority of these vintage monitor scopes have aged, leaked, cracked, blistered, melted, and infact lost their intended values from when first constructed. Especially the older paper electrolytics are prone to leakages. The CRT trace line has deteriated to just a blur in many cases, and will not focus sharply. The controls have either stiffened up or frozen due to the aging of the grease within them.

This old SB-610 Monitor Scope has now been completely - Redesigned, Modernized and Updated as of January 2006. I call it ... "The 610C-3 Monitor Scope". All electrolytics, tubular, resin, mica, and disc ceramic capacitors have been replaced with brand new - high quality components of higher voltage values. The two high voltage .02ufd 1.6kv, and .001ufd 3kv disc capacitors were replaced as well. Resistors in the Intensity, Focus, and Power Supply sections, as well as "all" of the remaining resistors, have also all been replaced & upgraded. All half watt resistors have been replaced with new Xicon One Watt 5% Carbon Film Resistors. All old one watt resistors have been replaced with either new Three Watt 5% IRC Thick Film Resistors or with One watt Xicon resistors. The Old - Out of Date - Selenium Rectifiers have all been replaced with modern 1N4007 Vr/1000vdc diodes. Even the 1N191 Germanium diode has been replaced. A Photograph of the typical New Parts replacements and Upgrades under the chassis may be seen by going to the below link and attached page. The Control Pots have been completely disassembled, cleaned with 90 Proof Denatured Alcohol, and relubricated. They now operate "silky smooth". There is a 455kc IF CAN (Heathkit P/N 40-746) installed in the new 610C-3 Monitor Scope for Collins S-Line, and KWM-Series Receivers. The trace line and wave patterns on the CRT are now "tack-sharp". The Photo below is of a typical S-9 SSB received wave pattern taken off the air on 20 meters illustrating some Flat Topping by the transmit station.





The Receive Wave Pattern ( RWP ) height on the CRT has been found to be directly proportionate to the length and resistance of the center lead in the connecting cable between the receiver and the scope. It is recommended that RG-58AU or RG-59 coax cable be used and that the length of the coax not exceed 5 feet. A 10pf Silver Mica capacitor, along with RG-174 thin shielded coax, should be used within the Collins S-Line Receivers/KWM-Series Transceivers from the Plate of the 2nd RF Amplification tube to the Spare RCA Jack on the back of the unit.





The faided and discolored paint on the old Heathkit cabinet has been completely beadblasted and sanded down to the bare aluminum. It is then professionally repainted with the S-Line color and duplicated trim ring. It is spotless and shows the high gloss luster of the original Collins cabinets. The front has been redesigned with a grill panel which meets specifications regarding grill hole angle, size, spacing, and number per inch as those on the Collins 312B-4 Station Control. It is slightly thicker than the Collins grills. The .032mm aluminum Control Strips are especially made by a company in Ohio, and are also simular to those found on the Collins 312B-4 Station Control unit. All aluminum on the front panel has been polished prior to painting and is then sprayed with a thin layer of primer. Each individual coat of paint is wet-sanded before another coat is applied. A total of seven coats of paint are applied to each Control Strip as well as the Front Grill. It bears the same dark gray color as on the original Collin's fronts. A second aluminum plate .032mm in thickness, which is painted black in color is bonded to the back of the front grill to give rigidity to the front. The three Control Strips are then bonded to the front grill. White 9-point commercial computerized lettering has been made by a graphics design company located in Atlanta, Georgia for the Control Strips. Several layers of clear coat have been applied to the grill, and over the lettering before final assembly. The Heathkit green Grid Screen has been replaced and redesigned by using a WordPerfect word processing program, to better match the S-Line equipment. The screen grid which is printed with a laser printer onto a clear transparency film - such as used in Overhead projectors - is then sandwiched between two layers of heat resistant bronze and clear color hard plastic sheets. Nine brand new Pointer Knobs have been installed, as well as a new heavy duty 3-wire AC power cord with grommet. Both of the old worn out discolored PL259 Coax Connectors on the rear chassis have likewise been replaced. The chassis has been cleaned with denatured alcohol. The original top and rear Tube, RCA Jack, Coax, and Knob markings have been replaced in many cases with new 10 point black computerized lettering. The unit sits on two new tapered risers and four brand new rubber feet. A Collins Appearance Round or Winged reproduction Emblem is on the front panel.




An article on the 610C-3 Monitor Scope was first published in the January, 2006 Collins Radio Association - Collins Journal - Volume 12, Number 6. The scope may be made with either a Round or Winged Emblem, both of which came from the Collins Radio Association ( CRA ) in Sidman, Penn. The New Reproduction Pointer Knobs are also from the CRA. Additional photographs are contained on the accompaning pages and are available through the below link. For further information please contact K4ZRD by e-mail.