New piece of CB gear - purists are gonna cry

[W2NAP]

Pic of the finished (for now) project:

Attachment 11691

You got to get a youtube account and make some vids man. really you should.

[N8YX]

i wonder if pat has any cb radios in his collection ...

Good question. Over the years, there were a lot of noteworthy models produced - and many used the same mainboard. The Cobra 148/2000GTL is a prime example. An older Popular Electronics review cited the '2000 as having the best adjacent channel rejection of anything on the market at the time. I had an early '148 (same chassis as the 2000 but sans frequency counter) in my car way back when and as good as the receiver was touted to be it would still get clobbered by nearby base rigs.

That fact led me to search out its true competition - not so much frill-wise as receiver-wise. A number of offerings from the era are considered collectible due to innovative design features (scanning or computer control), limited production runs, uniqueness (the Browning Golden Eagles and Demcos being the only true 'twins' in CB-land, for example) or snob appeal.

How many people would shell out $1k for a 40-channel, 4w AM/12w PEP SSB CB radio when < $700 would net you a Yaesu FT-101E with its 100w of VFO-tuned SSB goodness? People did, however - Tram's D201A, the Browning MkIV/IVa, the Stoner and CPI setups. You could easily tie up $1500+ in 1978 dollars in a full line of either of the latter two. Assuming SSB operation was your primary focus, either the Stoner or the CPI setups would run rings around the rest of the CB world in terms of receiver performance.

If Pat's collection criteria ultimately focuses on performance, those two definitely get the nod.

And if I were a smart man, I would take the shack's CP-400 (the mobile version of the CP-2000 base) and slave it to one of my R7s via an ARB-704 or similar interface...just using the CB set for its transmitter. Alas, that's too hard for 'DSG to figure out when we just want to have a quick bike-to-shack chat on 11M.

[N8YX]

You got to get a youtube account and make some vids man. really you should.

Well...let's see. I spent 5h of time in #439's power supply yesterday - most of which was spent trying to un-fsck it and return things back to "stock". Got the proper +5, +14 and +20v...so I installed the Exciter and Counter/PLL boards. Power-up, start checking things out - wait, what's that factory smoke escaping for? There is a 10uH molded choke installed from the base of the driver transistor to the anode of the biasing diode. It's overheating. Looking at the circuit, the only two ways this could be happening are if a collector to base short exists (it doesn't) or if the stage has gone into oscillation at or near the self-resonant frequency of the choke.

Needless to say, here's a YouTube of me in my lab during the event:

[N8YX]

#439 is partially back in operation with donor parts from #496. These include the Counter/PLL and Exciter Boards.

As detailed elsewhere on IoMH, I did something really stupid with the defective S/RF/SWR meter that came with #439 and essentially destroyed the signal/PO section. After a couple failed attempts to adapt a "replacement" unit which was shipped inside #496, I dug into my junk pile yesterday morning and liberated an S/RF meter from an old Royce CB carcass. Even though the movement itself was a drop-in replacement, the meter sweep was left to right - whereas the Stoner version uses a right to left arrangement, albeit set 90 degrees from vertical.

The design was studied and a workaround identified:

The torsion spring was unsoldered from the centering arm, both sides of said arm were flattened and rotated to bring the solder side into position for an alternate sweep arrangement then ~1/8" of the spring was carefully snipped off and the end soldered to the centering arm. The movement was then extracted from the Royce OEM plastic housing and inserted into the Stoner housing, after which the needle was zeroed with the centering arm.

Put the meter assembly back into the radio and test it out...works great.

Any Stoner owners coming across this post who are in need of replacement movements need look no further than a junk Royce 1-619, 1-640/642, 1-624/625 or 1-641. They all used the same type of meter.

It's also possible to mod one of these for the centered-needle "SWR" function.

I took #496's bottom cover with internally mounted speaker and swapped #367's bottom cover for it. Since I don't have one of the SPK40's yet (and am NOT paying the $250+ which many people think they're worth) this will allow me to run the radio without an external speaker for the time being.

One other addition was done: I had previously rewired #367's mic connector to mirror Ten-Tec's connector arrangement (mic audio/gnd/TX/9v on TX). So...I dug up a NOS Astatic 878DM for use with the rig. Since the radio supplies 9v to the mic's internal preamp on transmit, I don't need to use a battery with it - and I can switch the mic over to my Ten-Tec gear if desired.

Right now the mic's amplifier gain is set to provide ~6w PEP with the Pro40's compressor switch off, and this increases to 10-12w PEP with the switch on. Perfect for local ragchews.

[kc4umo]

Nice thread.
Always good to see someone bring these type of radios back to life. Been a while since I had one of these on the bench. The last one that was on the bench went for 600 bucks on ebay and that was a few years ago.
Great job!

[N8YX]

Nice thread.
Always good to see someone bring these type of radios back to life. Been a while since I had one of these on the bench. The last one that was on the bench went for 600 bucks on ebay and that was a few years ago.
Great job!

This is going to get a lot better. How about a stabilized synthesizer reference, 4 RX IF bandwidths (front panel selectable), 4 AGC settings (slow/med/fast/off), also front panel selectable...a mic gain control, possibly an IF Gain or RX tone control. Or maybe a variable filter bandwidth control. The front panel will look stock, albeit with concentric controls for the extra functions.

And the coup de grace: One of those cases will end up housing an SBE LCB-8 as the AM section of the deal. It, too, will look "stock". All mods will be reversible and the channel/clock display will mimic the Stoner's:

CH19A-12:00P

The "A" and the "dash" are going to indicate whether or not the rig is tuned to an RC channel, or is on the "normal" 40CH allocation. A "L" and a "H" range will be provided, and the transmitter will be locked out on all of those ranges unless the planned 80/40/20/17/15M transverter is connected and powered on. Similarly, a lockout will exist within the Pro40 itself: Old man Stoner had the synthesizer programmed so that grounding a pin will enable coverage to 27.865. Unless a transverter is connected and activated, it'll only RX on those frequencies once I'm done with it.

[kb2vxa]

This thread like many in this forum brought back some fond memories including a couple of funny ones. One in particular is the Dumbco Power Mutilator mic preamp that was a 2.5W power amplifier, a 12AX7 dual triode driving a 6AQ5 power pentode. The funny part is why a power amplifier that can't deliver power into a high impedance (50K+) load presented by the first stage of a speech amp designed for a crystal mic? Now we have another POS crapping up the band, it don't mean a thang if ya ain't got that swang (do wa do wa do what?).

OK, CB isn't ALL bad, but it reminds me of a Top 40 AM station of old "where the shits just keep on coming". You guys have the right idea, take the best of the best, make a few improvements, and use them as QRP rigs on 10M where you can tune up the band out of range of those annoying freebanders and renegade truckers.

[n2ize]

STONER? If you accidentally let the smoke out stick your head over the radio and breathe deeply. Recycled smoke has its uses. Anyway, if you're going to so much trouble to design a micro for it the rest better be made out of gold. Oh, if you hear lightning crashes on 11 or 10M the storm is too close for comfort.

And if you hear them on a Geiger Counter you know the storm is way closer than closer for comfort. ;)

[PA5COR]

Made a bundle 15 or more yearss back putting in monolithic 10.695 Xfilters into the radio's.
Most I.F's had several cans coupled with a small C replaced one c put in monolithic Xf and do a tweek up, done.
That surely cleaned up reception and channel "bleeding" over.

Still have some of them in a drawer or so, left over from the project.