|
|
Post by crambone on Mar 11, 2019 22:52:03 GMT -5
Anyone have any info on this I need a schematic. NO I didn’t butcher this Radio I’m trying to fix it as it was already there. I believe it to be a Kem Tron? Attachments:
|
|
|
|
Post by 2600 on Mar 13, 2019 17:37:06 GMT -5
Not familiar with that one. Data for the Mitsubishi chips in it don't turn up where I normally look first.
Biggest problem with adding a display like that to a D201 is supplying sufficient 12-Volt power. The radio's internal 14-Volt regulator won't have the current capacity to light up six digits made with 1970's technology. They tended to be current hogs, compared to modern-day display digits. Typical way to do this was to squirrel away a small wall wart inside the radio. Plenty of room for it.
What kind of issue are you having with it?
73
|
|
|
|
Post by crambone on Mar 13, 2019 19:18:45 GMT -5
I figured out the power for it but one wire was hanging and I just can’t figure out we’re it goes. The way it’s currently wiredit only shows the frequency when the microphone is keyed. Also gives me a ton of noise when it’s powered on. I was going to try to decouple it but thought maybe that one unattached wire is my issue.
|
|
|
|
Post by 2600 on Mar 14, 2019 0:15:15 GMT -5
The unattached wire is probably the antenna, serving as the input to the counter. It appears to be a basic counter that can only show you the carrier frequency while you're keyed and transmitting in AM mode. And, of course, not modulating it. Audio modulation will generally disrupt the reading, and causes "dancing digits" until you quiet down and give it a dead carrier to achieve a steady count. Won't read properly in sideband modes, with no steady carrier to count. This type counter was popular decades ago, built into an enclosure with two SO-239 coax sockets on the rear. You would put it in the coax line coming out of the radio. Pretty sure this one was removed from its enclosure to install inside the Tram. This kind of counter simply counts up from zero to show you the carrier frequency you feed into it. Counter displays like seen in the Cobra 2000 or Galaxy radios that show you the receiver frequency full time without keying the mike are different. Those "displays" do some internal arithmetic. The "offset" is the difference between the internal frequency synthesizer's output and the channel frequency. A full-time frequency display does this arithmetic internally. In a D201 it would add 6.2565 MHz to the 20.7085 MHz that comes out of the crystal-synthesizer board on channel 1. If you connect the input of this counter to the output of that board, it would read 20.7085 all the time, transmit and receive. There are 6-digit counter/display boards sold on Ebay for under 15 bucks. They are too large to fit behind the windows on the front of the D201, but they'll do the job. www.ebay.com/itm/PLJ-6LED-A-RF-Signal-Frequency-Counter-Cymometer-Tester-0-1-MHz-65-MHz-Blue/200952879004?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649The offset frequency is set with a couple of pushbuttons on the rear of the pc board. We make a 'piggyback' board that takes the place of the large digits on these boards. grumpy.proboards.com/thread/8003/digital-frequency-display-tram-d201Gotta come up with better installation instructions for it. 73 |
|
|
|
Post by crambone on Mar 14, 2019 13:16:57 GMT -5
Yup you hit the nail on the head. Funny you just showed the counter I ordered 3 days ago to try out.
Thank you for your reply I appreciate it
|
|
|
|
Post by 2600 on Mar 15, 2019 23:11:42 GMT -5
I do have one suggestion about the SanJian PLJ-6LED counter display. The input circuit has two back-to-back diodes. This limits the input level to the counter's preamp protecting it from a high drive level. But will load down the circuit you feed into it if connected directly to the input leads. A 220 ohm resistor in series with the hot side of the input lead will prevent the counter from loading down the radio's synthesizer-board output and reducing the radios performance.
73
|
|
|
|
Post by crambone on Mar 16, 2019 23:07:37 GMT -5
Great info thank you
|
|
|
|
Post by aardvark on Mar 17, 2019 6:59:22 GMT -5
|
|
|
|
Post by 2600 on Mar 17, 2019 16:42:24 GMT -5
Yes, it should fit. You'll have to fab a bracket. We have used this display. My customers don't like LCD displays, and asked for a LED version so we abandoned the PLJ-0802 counter before I could get good pics of the setup.
Don't have a pic of that install, looks like.
I do recommend putting a resistor in line with the hot side of the power connection. Can't remember the resistance value, but you want to drop the radio's 14-Volt supply down to about 9 Volts at the LCD display's power jack. The display's dropping resistor for the backlight might overheat running directly from 14 Volts.
And you'll still want that resistor in line with the signal input. Pretty sure 220 ohms worked okay for that.
Biggest headache besides the mounting bracket is getting the plastic dial off the tuning shaft. They're held in place with some sort of locking goop. You have to first remove the screw that holds the big coil next to the VFO capacitor. The two screws that secure the capacitor's bracket are obscured by the coil.
By all means check back with us and post a pic once it's installed.
73
|
|
|
|
Post by crambone on Mar 18, 2019 22:14:50 GMT -5
excellent, thank you!
|
|
|
|
Post by crambone on Apr 1, 2019 19:04:02 GMT -5
Updat: figures out the frequency counter wiring everything working.
Thank you everyone for your guidance and help!
|
|
|
|
Post by 2600 on Apr 1, 2019 21:34:48 GMT -5
Rock on!
Congratulations for sticking with it.
Gotta love it when a plan comes together!
73
|
|
|
|
Post by crambone on Apr 1, 2019 21:36:57 GMT -5
Ya it some some time but learned a ton! Now onto the modulation issue. 😞
|
|
