So I picked up a new piece of test gear for my radio tweaking lab…
I have a 200KHZ Signal Generator, but it is analog… I wanted something that will sweep, and the 2 channel will allow 2 tone checking of SSB…
So I found a JDS6600 DDS Signal Generator/Counter 2 Channel that goes to 40 MHz
Not bad for ~$85 off ebay… it will work…
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via US Pro-Gun Rallies in all Capitols — Reality Check
I have been redoing my Station Grounding a bit at the QTH…
Ever since I moved out here to the desert, I’ve never been totally happy with my transmitter setup, and I could always sense a little RF in my audio… not cool…
Literally, while transmitting in SSB and monitoring on a O’Scope, when you key the transmitter with no modulation, it SHOULD be a flat line on the O’scope, until you speak… mine was always a tad twitchy… and I could see, and hear the noise on the Monitoring radio…
Now ever since I started playing with ESSB, for the most part, I’ve used MXL Microphones. They sound great and are at a great price point. I have a few of them, and since I also play guitar, what isn’t being used on the Radio setup is pressed into duty recording other noises… music
I recently picked up a MXL 2008 Condenser Microphone from Massdrop. The 2008 sounds like it should be great for doing some HiFi Radio…
Cool… right?
So here it is mounted in a Shock mount, with Pop filters installed..
This weekend, I started chasing my RF in the audio problem:
Mic Cables are solid and cap bypassed, New grounding scheme is solid (<2 Ohms from any component in the systems Star Ground Point to the 8′ ground rod), Audio rack is in good shape.. except I have a burned out meter bulb in the Modified Bellari RP-503 (Bellari doesn’t pay attention to the Pin 1 problem either, but I fixed that 10 years ago before I put it in-line).
Then I noticed something…
On the Bellari RP-503, turn the Phantom Power Off, the Noise on the Transmitted signal was reduced, but still there, turn the phantom power back on and the noise comes back…
I turned the Phantom Power off and grabbed my indestructible EV 635A/B Dynamic Mic, disconnected the MXL 2008, and hit the transmit… Flat line until modulated, no RF noise I even tweaked the rack levels to get the proper ALC deflection on the ICOM… and it was still quiet…
I may have found my Guilty party, and I thought of the “Pin 1 Problem”, and you can read more about that here from the Rane Library: Pin 1 Revisited
Time to take a look:
The patent:
I pulled the body apart and investigated the XLR connector… and I didn’t like what I saw:
Pin 1 is where the Black Wire is connected, and it also jumps over to the Mic case ground. The jumper is good, but that Black wire is not.
I started chasing the Black wire to see where is would lead:
As you can see, the black wire goes to the “Ground Plane” on the circuit board, which is a classic Pin 1 problem. The Pin 1 is the Chassis Ground and should be totally isolated from the Circuit ground, so the metal body of the microphone can act as an RF Shield for the rest of the Mic circuit. Also, the 2 screws that hold the circuit board to the Chassis go through the same ground plane.
But wait, it gets better….
If you have a sharp eye, you might have already spotted the issue:
So the circuit board ground is tied to Pin 1 with C1, C2, D3, and the Inductor below Q1, but it gets worse: Look at the Ground Wire from the mic element…
Grab the trusty DVM: Black Lead on Pin 1 of the XLR, Red Lead on Mic Element Negative…
Damn! That short doesn’t get any deader than that.
I guess it is time to figure out how to isolate the Chassis Ground from the Circuit Board Ground to keep the RF out of my Audio.
I have a hand full of MXL Condenser mics, and now I’m starting to wonder how many of then have this issue.
I’m betting all of them…
For now, its back to the MXL BCD-1 Dynamic Broadcast Mic, which is properly wired, I checked last night.
More to follow….
Gots me an update..
Friday I swung over to Petsmart an picked up 6 fish (buy 4, get 2 Free). They are “Feeder” goldfish, but the girl helping me out decided to get me some “Cute” ones….
So fish in Friday evening, and that night, I made a cover for the “pond” to help cut down on evaporation losses…
Here is is Sunday afternoon.
No losses of Fish yet. Water is staying 85-90 degrees, and my zucchini seeds is a sprouting!
This might just work after all….
I always wanted to try this… After doing some lookin’ and a friend showing me his little setup, I talked myself into giving it a try.
I wanted to do it for less the 1 Benjamin…
I got the almost exactly, but not quite real, Resin Whiskey Barrel at TSC 1/2 price at $13
The 360 GPH pump was $20
Window box planters with $7 early at Lowe’s
Had the plant pots, PVC, and gravel.
Air pump and air stone were like $15 total at Walmart.
I just got it together and I’m letting it run to see if the water clears up.
I’m betting it is about 20-25 gal. 1/2 price at $13
The 360 GPH pump was $20
Window box planters with $7 early at Lowe’s
Had the plant pots, PVC, and gravel.
Air pump and air stone were like $15 total at Walmart.
I just got it together and I’m letting it run to see if the water clears up.
I’m betting it is about 20-25 gal.
Probably going to start with some goldfish, and they are tough as nails and dirt cheap…. Oh, and they shit… A lot…and that makes for happy plants…
While on business up here in Las Vegas, NV, I was able to visit my buddy Kelly Poots over at Kelly’s CB Radio in North Las Vegas.
Prior to coming up, I hit him up to see if he by chance had a Uniden PC122XL hanging around the shop in need of a home…. you know, I had to save up my milk money… He told me he didn’t have a PC122XL, but he had it’s long lost twin, a Realistic TRC-453…
A quick trip to http://www.cbtricks.com for the specs on the TRC-453 told me it would be perfect for my Next Verison of the Ammo Comm Can. Sure I would have loved an Export Rig that could pull off 10/11 meters, and all points in between, but them critters don’t come in size Small…
I was looking for a bit of heat to put behind it as well, just a little kick, like a KL-203. Kelly didn’t have one of those, but he did have a Silver Streak 150…. I told him when I got into town, I’d be over to take a look at the equipment, and Indian Leg Wrestle him to get the prices down to my Milk Money range
When I got into town, I made some time to swing by and see Kelly. Being the true classy gent that he is, he pulled out the TRC-453 that came with an old school Diesel 360-6 Power Mic attached, hooked it up to a dummy load, and ran it through the checks WITH and O’scope showing the truth to go along with the meter: The radio was setup for a 2 Watt Carrier and 100% Modulation (Swing is for people that like to see meters bouncing around…). Using his Bench receive radio, he demonstrated on air audio in AM, LSB, and USB.
Then he pulled out and hooked up the Silver Streak and did it all again. The Low Power Setting looked clean with the 2 Watt input it was doing about 60 out. and modulated about 120. The High Power wasn’t quite as linear as the low power… but that isn’t a surprise, most “Linear” CB amps Ain’t Linear…. and the High power setting wasn’t enough of difference to be heard on the receive end anyway… Leave it on Low,it will live forever…
I was happy with the setup; sure it was cosmetically showing its age a bit, but cosmetics don’t matter on the air…. Then Kelly threw in a power cable for the Radio, a Coax jumper, and extended the power leads on the Amp… SOLD
The TRC-453 gets nothing but solid reviews from being a great AM talker, and a solid, drift free performer on SSB.
Since I had an off work day today, and I don’t dig Vegas, I decided to give the new setup a looksee….
The Radio was build in Taiwan in the ’88/’89 time frame
I popped the lid to see how the inside looked: Stock and Unmolested
and of course, the Uniden board.
Of Course, looking at the schematic provided by CB TRICKS, the radio is about 2 capacitor swaps away from having some more BASS in the AM mode TX Audio…. hehehehe
The Diesel 630-6 Power mic. 
I popped the cover on that hoping to find an ID mark on the board to help me track down a schematic for it.
Of course, I didn’t get that lucky….
I have a demented dream of taking a power mic and converting it to have more of a Mid-Fi/Hi-Fi sound without any outboard processing…. truly Portable sound that definitely “stock” sounding… Probably be a couple Cap swaps and a new, wider range dynamic mic element would do it…
So if anyone know where to locate a schematic of this mic, please let me know to save me from tracing out the circuit…
I’d say the only down side is the 5 pin DIN plug, I know they make 5 to 4 pin mic cable adapters, but this rig is slated to be shoved into and Ammo Can Setup, and with it being a side plug model radio, real estate can be an issue real quick in the confines of the Ammo Can.
So then I decided to inspect the Silver Streak 150
The face plate could use a bit of cleaning, but that is to be expected with a piece of equipment of this vintage
And of course, being I have a screwdriver and few morals, I had to see what the guts looked like, as some amps can be scary inside to say the least…
Inside looks unmolested to… outstanding. Well lookee there, a pair of Toshiba 2SC2290 transistors… and the build looks clean…. nice.
So the plan is to build another Ammo or Flare Comm Can project using the TRC-453, Silver Streak and a pick up the new B-Tech UV-50×2 VHF/UHF Rig, since I’ll need to beef up the power supply to the box due to the Silver Streak, or rebuild the Original Comm Can and reuse the QYT KT-8900 and save some cash…
Decisions, decisions…
Until next time…
I decided to tackle another Comm Can Project, this tie for a road trip I had to do for work. Basically, the trip was about 5 hours via a lot of area where cell coverage is a bit spotty, to say the least.
I knew I would be renting a car for the trip, and needed to be able to throw some radios in, and would power them from the Power Port (more commonly known as the Cigarette Lighter!).
The “Ammo Can” I used this tie is actually an Aerial Flare Storage Can. It is the same Height and Width and the 50 Cal Ammo Can, but it is 3.5” deeper at 9.5”
The hope was to get my Yeticom Optima Mark III in the box to allow me to run AM and SSB on 10/11/12 Meters… nope, the radio is too long… I couldn’t find a Uniden PC122XL, which is probably the smallest 11 Meter AM/SSB rig ever made… so….
The Radios chosen for the project were the Anytone Smart CB again, and a B-Tech UV-2501 VHF/UHF. Also added into the mix would be my old Magellan GPS for finding my way around….
Here’s the Box:
So I decided to do the insert different this time and not make it solid walled like the last one. This was to ease maintenance, modification, and construction.
3/8” Birch Ply for the Face Plate, 1×2 furring strip for the frame, and ¼” Ply for the “floor”, and prefab metal strip to make the mount rails:
The face plate was measured, marked out and cut using my new Rockwell Blade Runner 2. Great tool for doing projects like this and only $99. It is basically and upside down Jig Saw mounted to a table. It also has a fence to help keep the cuts straight.
Holes were cut for the 2 radios, a slot between the radios for cooling air intake, GPS/Fan Exhaust, and one to drop the microphones down in for storage.
The terminal strip under the GPS was wired up from the Anderson Power Pole receptacle with 10 AWG and the other terminals were daisy chained off that.
A Female 12v Inline plug was wired in to the terminal block to allow plugging in the GPS Power cable without hacking it up and still provide the required 5VDC to the GPS.
A bracket was fabricated to hold the 2” Muffin Fan running at 15.5CFM… Yeah, it circulates the air through the box pretty well…
Power to the box is provided by a standard cigarette lighter/power port plug… not idea, but I’m not going to wire up a rental.
Power on Smoke Check!
No Issues.
Decided to install a USB/Power Port on the side to charge phones on the outside of the box, due to space constraints, it isn’t all enclosed, but it is very portable. The external power plug was wired to the terminal strip.
Here it is installed in the rental for the trip, working great….
No external speakers were required for the radios as there is enough holes in the face plate, and the radios have enough audio drive in that small area to be heard with no trouble.
The Antennas being used are a Comet 2M/70cm mag mount and President New York 11 meter Mag Mount.
The good news is I acquired a Realistic TRC-453, the no so distant cousin to the Uniden PC122XL… It is capable of AM/SSB on the FCC 40 channels, and is short enough to fit in one of these flare cans, so I see a Comm Can Ver. 3 in the future; Possibly with a Silver Streak 150 behind it (which I also just acquired) to help me reach out and touch someone….
Guess its time to pick up another VHF/UHF rig too…
Until next time….
