Approximate Dimensions:
The main chassis of the 6x2 receiver is a box constructed of aluminum sheet and bar stock. A thick front panel made of aluminum sheet is then securely fastened to the box.

The main chassis dimensions are approximately 12" wide, 9" deep, and 3" high. The sides are made of 3" wide x 9"long x 1/4" thick aluminum bar stock, and the top, bottom, front, and back panels are made out of 1/16" thick sheet aluminum. The dimensions of the top, bottom, front, and back panels are adjusted/sanded to give a clean tight fit when the chassis is assembled.

The front panel is made of 3/32" thick sheet aluminum, 12" wide and 8 1/2" high. The front panel is held onto the main chassis with four 4-40 screws and the shafts of the AF GAIN, BFO, CALIBRATE, and IF GAIN controls.

If you zoom in on this super detailed side view you will get a good idea of how the chassis and front panel are structured.

Main Chassis Construction:
The main chassis of the 6x2 receiver is a box constructed of aluminum sheet and bar stock. Though a commercially made chassis made of bent/folded aluminum could certainly be used, I prefer this type of construction because I am familiar with it and it results in a firmer, more rigid chassis. This is the same construction that I used in my 6146 Amplifier and my Wingfoot 813 Amplifier. Rigid construction, so neccessary for stability, is even more important in a receiver than it is in an amplifier.

The main chassis dimensions are approximately 12" wide, 9" deep, and 3" high. The two side panels are made of 3" wide x 9" long x 1/4" thick aluminum bar stock. The top, bottom, front, and back panels are made out of 1/16" thick sheet aluminum. The dimensions of the top, bottom, front, and back panels are adjusted/sanded to give a clean tight fit when the chassis is assembled.

The side panels are drilled and tapped on all four sides to accept 4/40 screws. The other panels are then fastened to the side panels with 4/40 pan head screws.

Note that the front panel does not form the front side of the chassis. There is a separate 1/16" panel between the receiver front panel and the front of the side panels. This construction allowed me to mount the front panel controls on the 1/16" panel while testing and developing the receiver, and then add the final front panel later. It also provides strength and support to the front side of the top panel, which is very important. Do not omit it! (This extra panel is more easily seen in the photo below.)

If you zoom in on this super detailed rear view you will get a good idea of how the main chassis and front panel are put together.

Main Chassis Bottom View:
In this bottom view of the main chassis you can clearly see the holes in the 1/4" x 3" side panels that have been drilled and tapped to accept the screws that hold on the bottom panel. If you carefully look at the back panel at the rear of the photo you will also two see small "L" brackets that are attached to the middle of the back panel. (One is behind the white ceramic resistor at the rear of the photo). These are drillled and tapped to accept 4-40 screws. These connect the back panel to the top and side panels to provide additional support for the back panel and to eliminate the possibility of vibration.

If you look carefully at the front of the photo you will see that there is a 1/16" panel between the actual front panel of the receiver (which is 3/32" thick) and the front of the side panels. The two panels are held to the side panels with four 4-40 pan head screws. The front panel controls pass through both panels. This construction allowed me to mount the front panel controls on the 1/16" panel while testing and developing the receiver, and then add the final front panel later. It also provides strength and support to the front side of the top panel, which is very important. Do not omit it!

Front Panel Construction:
The front panel is made of a single piece of brushed aluminum 12" wide, 8 1/2" high, and 3/32" thick. Do not use thinner aluminum. Thick aluminum is necassary to prevent the front panel from flexing during operation. Thinner aluminum will flex, for example, when the receiver is tuned, introducing slop and backlash.

Control functions are stamped into the front panel using metal letter/numbering stamps available from sources such as Harbor Freight Tools and MSC Direct. You must be very careful when using these stamps, since you can't erase a mistake! Practice with them first before making the final impressions on the front panel. You can, of course, also use stencils or a label maker.

The National ICN illuminated dial is mounted to the front panel and connected to the main tuning capacitor through a flexible coupling whcih smooths out the tuning. The mounting holes for the ICN dial and the through hole for the tuning shaft must be slightly larger than normal so the dial can me moved around for a perfect fit with the main tuning capacitor shaft. Alignment must be done after the front panel has been mounted to the base of the receiver. There must be absolutely no binding with the main tuning capacitor shaft. Once in the proper position, the ICN dial can be tightened into place.

Front Panel Rear View:
In this picture the back of the front panel can be clearly seen. The shaft of the band capacitor (the dual section capacitor at left in the photo) passes through a generous hole in the front panel to prevent binding.

The shaft from the National ICN vernier dial extends through a generous opening near the center of the front panel. The ICN dial is mounted so that it can be moved around to obtain perfect alignment with the main tuning capacitor. After perfect alignment is obtained, it is then secured to the front panel.

I was lucky to have a brand new ICN dial with all of the original hardware. The #47 pilot lamps that illuminate the dial mount on hardware provided with the dial. They pass through holes in the front panel and extend into the housing of the ICN dial. If your dial lacks the original hardware, you will have to improvise based on the photo.

The MODE switch is mounted on the front panel at right in the photo. Wires to the MODE switch and pilot lamps pass through a grommeted hole in the top of the chassis.

Top Panel Construction:
The top panel holds most of the receiver components. The top is supported on all four sides by panels underneath all four edges. This is very important in preventing any flexure of the top panel which can lead to microphonics. Though the receiver does have slight microphonics, they are at the same level as commercial receivers such as my Hallicarafters SX-96.

Like the controls on the front panel, the components and tube sockets on the top panel are labeled with their functions by using metal letter/numbering stamps available from sources such as Harbor Freight Tools and MSC Direct. You must be very careful when using these stamps, since you can't erase a mistake! Practice with them first before making the final impressions on the panel. You can, of course, also use stencils or a label maker, but heat from the receiver may discolor some of these.

The most critical tube, the 6U8A mixer, is mounted directly behind the front panel as close as possible to the main tuning capacitor, which is near the center of the photo. A tube shield is used on the mixer tube to shield it from any external fields. Only the front 35pf section of the main tuing capacitor is used. Though not visible in the photo, the stators of the other three unused sections are shorted to ground to prevent their interacting in any way with the active section.

The power transformer and output transformer are mounted near the edges of the top panel to provide firm support. Holes for these were made with an Adel Nibbling Tool, a tool every serious builder should own. Holes for the tube sockets were punched using Greenlee chassis punches. These are expensive, but worth the cost if you make more than one piece of gear. Lacking chassis punches, the Adel Nibbling Tool can be used to make the holes.

Any wires passing through the top panel, such as those from the band capacitor, main tuning capacitor, and mode switch, should be passed through grommeted holes.

The crystal Y1 and crystal filter phasing capacitor C3a are mounted in an octal socket which allows some experimentation with these. These must be as close to the output of the mixer as possible. The crystal Y3 for the crystal calibrator is mounted in a cermanic socket directly behind the the band capacitor. Tubes that produce a lot of heat, such as the 5Y3 rectifier and 6AQ5 audio power amplifier, are mounted as far as possible from the local oscillator and BFO to prevent their heat from producing drift.

Rear Panel Construction:
Like the front panel, rear panel functions are stamped into the back panel using metal letter/numbering stamps available from sources such as Harbor Freight Tools and MSC Direct. You must be very careful when using these stamps, since you can't erase a mistake! Practice with them first before making the final impressions on the front panel. You can, of course, also use stencils or a label maker.

At left in this photo of the receiver back panel you can see two antenna connectors, an RCA and an SO-239. These are connected in parallel and allow the receiver to be used with just about any system, without having to resort to an adaptor. To the right of the antenna connectors is the line fuse and line cord. An octal socket is mounted on the back panel as an accessory power socket to run accessories such as a converter. The speaker output is the RCA connector on the far right.

Note the two pan head screws in the middle of the panel at the top and bottom. These are attached to small "L" brackets that connect the back panel to the top and bottom panels for additional stability.

Not shown in this picture are an RCA mute jack and mute toggle switch that give the receiver manual/automatic mute capability. These were added later, after the receiver was finished. They were mounted between the line cord/fuse and accessory socket.