New piece of CB gear - purists are gonna cry

[K7SGJ]

#367 is fully operational and chugging away as I type this. Had to set the S-meter adjustment, notch filter depth...rewire the mic connector to the 4-pin Ten-Tec standard so I can use one of several on-hand mics with the rig. Carrier balance set, squelch threshold set...internal mic gain set. Puts out a full 12w PEP.

'TNS did a very slick thing when he designed the radio. Channel selection is done by 4 switches - slow up/down and fast up/down. The PTT line is wired in such a way that if any of those switches are depressed, the radio won't transmit.

Of course, it goes without saying that if any of those switch contacts are dirty, the PTT signal won't appear at the mic connector.

DeOxIt spray is your friend. Really.

Two hours of the morning were spent running down parts to fix the other radio. Once it's up and running, #439 will become my "test mule" for some modifications I'm planning. It turns out that certain Watkins-Johnson radios use the same IF as this set, and it also turns out that I managed to snag two 2.0KHz, a 3.3KHz and a 6KHz filter from those radios. So...Phase 1 of the selectivity upgrade will consist of the design of a daughterboard which accommodates the stock filter, one of the 2.0KHz filters and the 3.3/6KHz pair. As is done with the Drake TR7, I'll use the stock SSB filter on TX then allow independent RX filter selection via front panel switch.

Phase II might consist of said daughterboard but instead of the two wider filters I'll substitute three of my own design: One of ~2.8KHz, one of 4KHz B/W and the fifth set up as a variable bandwidth or variable center frequency with a fixed 2.4KHz B/W.

There be...possibilities. Lots and lots.

I need to design another front panel board too - the new control layout requires ganging the AF and RF Gain controls, doing the same with the squelch and notch ("whistlestop") functions, incorporating ganged switch/potentiometer assemblies for the AGC/Mic Gain and B/W Selection/VBT controls. Jury is still out on that "Mic Gain" control: It could turn into an RX Tone control when all is said and done.

A number of people have made the observation that the radio drifts. Yes, it does. Specifically, the counter: It's a direct reading type. The timebase is a crystal oscillator which uses a 2.560MHz HC-6/U rock with no temperature compensation scheme. I can design one for it, or I can get clever and build a different reference oscillator using a DDS and a PIC to load the control sequence at power-up. Drift is negligible with such an arrangement and spectral purity isn't much of an issue - the reference is used to drive a TTL divider chain which has a low-pass filter at its output.

I'm also planning to build a separate 5v power supply into the case, as a number of other owners have done. The main supply runs much cooler as a result.

Dave, I'm looking to build another case which matches the appearance of this radio and drop the guts of an SBE LCB-8 into it. The radio has no AM function so a companion AM set might be what the doctor ordered - and in the RX department, the SBE is a pretty decent performer.

As far as



goes, that might be enough to raise Mr. Stoner from his grave and induce his corpse to walk the U.S., find your flat and choke you.

Weekend at Stoners'?

[N8YX]

Weekend at Stoners'?

Nope; the in-law's.

I always cry at weddings. Especially if they're too long.

Last part of this phase of the project is finished: I connected up a CPI CP-400 to the Pro-40 via the "CB-AM" connector. The CP-400 uses the same mainboards as the vaunted CP-2000; in fact, a '2000 is in essence a '400 with a few more controls and another meter brought out to the front panel. So...I can perform A/B tests between the receivers.

Early results: With the Pro-40 set up as per the 'Performance Checkout' section of the owner's manual, let's just say that - apart from the neat functions like an onboard audio notch/peak filter - Stoner Owners might be a mite bit disappointed, given the radio's reputation. The neighborhood lidiot with the peaked-out export radio still clobbers any receiver I put online including my commercial stuff. I had hopes for the Pro-40 in that I could monitor CH38 with the squelch set to minimum and not have Bozo trip it open with a bunch of splatter.