Batboard

kcbooboo

The MIC Audio on the front panel has about 9VDC on it to power the preamp built into almost all Motorola mikes. Since one doesn't normally plug a mike into the Acc Conn, they don't provide power on the TX Audio input for that. Also the front panel MIC Audio input is pre-emphasized; the Acc Conn TX A...

kcbooboo

I don't know if the Quantar is such a station, but some Motorola radios require the code plug IC to contain some information before the station (or radio) will accept them and let you proceed. Things like Spectra mobile radios, R100 repeater radios come to mind. It's easy to replace the chips but wi...

kcbooboo

The mike input impedance is around 600 ohms. Your weather station might be expecting a higher impedance load, and it just doesn't have enough drive to make the GM300 work. See if you can add a small buffer amplifier between the two. You'll need around 80mV per kHz of deviation when plugged into the ...

kcbooboo

Most Motorola equipment uses op-amps in the audio stages and run them from a single positive power supply. This means all the audio signals run with a DC bias of around +4.8VDC. That's just the way they were designed and you have to live with it. You should always use a coupling capacitor when deali...

kcbooboo

I have an R2001B, which is almost identical to the C. You can fold the front panel out about 45 degrees after disconnecting the CRT shield and a few other screws around the perimeter. Check that all the cable connectors are fully seated, especially the flat cables going to the LED/switchpad boards. ...

kcbooboo

One of the LEDs in the column to the right of the power switch should also be lit up. It's possible that one function has been selected with the up/dn arrows below, and that particular LED is bad and is therefore not lighting up. In fact, one LED in EACH column should be lit up; there is no "Al...

kcbooboo

I pulled apart, to clean, dozens of CDMs. I took the entire molded plastic control head "housing" to the kitchen sink. As I recall, the circuit board had the display clipped to it. You don't want to remove the LCD assembly because the zebra strips require careful alignment to insure it all...

kcbooboo

You can remove the knob first, but it's easier to do after you've removed the circuit board. It has some outward-spreading clips that hold it into the hole in the front panel, and these can easily be compressed from inside if you need to remove the knob. So ignore the knob for now, pry the head off ...

kcbooboo

The control head can easily be taken all apart with nothing more than a plastic prying tool or a small flat-blade screwdriver. After that, clean the carbon trace contacts on the front of the pcb, clean the silicone button assembly and all the plastic parts. I usually wash them in hot water and some ...

kcbooboo

Perhaps the control head is dirty or bad? All the pb switches generate two analog voltages based on "row" and "column". Take the control head apart, make sure the pcb contacts under the silicone buttons is clean. Someone could have poured soda or coffee into the radio. Try anothe...

kcbooboo

"Can anyone please direct me to a place?" http://www.repeater-builder.com

"Any ideas?" VCOs failing to lock. Check the electrolytic capacitors on the Uniboard. There's an article on the above web site.

Bob M.

kcbooboo

Most of the data in the R2001 series is sent around as binary-coded, over four or eight lines. I immediately noticed that the "4" bit is stuck in one position, since 0,1,2,3 display correctly but 4,5,6,7 show up at 0,1,2,3. In binary, 3 = 00100011, 7 = 00100111, so the 00000100 bit seems t...

kcbooboo

Sometimes a local microphone will key the station and include PL/DPL along with it, whereas an XMIT button or slide switch may only key the station with no modulation at all. If there's a PL/DPL encode board in the control tray then the output of that should be checked to verify that it's putting ou...

kcbooboo

Don't give up so quickly. The MICOR seems overly complicated at times but you can force it to do what YOU want by making modifications to the backplane and plug-in cards. Lots of people are running MICORs with CW ID that comes out with PL/DPL. There are multiple audio inputs and multiple PTT inputs;...

kcbooboo

Most Motorola base/repeater stations do NOT transmit PL/DPL when doing a CW ID, at least if it's being generated by the internal logic or controller. It's designed that way on purpose. You will need to connect an external CW ID differently if you want the PL/DPL to be transmitted when the CW ID fire...

kcbooboo

Open the radio and check the HLN numbers on the RF and PA boards. They're either on small white stickers or stamped in ink on the board. Then you won't have to "guess" any more. Once you determine what band the radio really is supposed to be on, blank it and reinitialize it. TX Power norma...

kcbooboo

Correction to the above post: The first letter is "H"; the second letter is "L".

Bob M.

kcbooboo

Low-band MaxTracs are only rated for 60 watts RF output. If you crank it all the way up, the power control circuit DC output will be sensed by the cpu as being too high and it will do exactly what you are seeing: TX briefly then cut off. If the radio has been modified or is operating out of band, th...

kcbooboo

The data signal when you release the PTT could be "post-MDC". It sounds like you need to completely reprogram the radio. Check the "SL" steering-line test point on the RF board and verify that it's between 2 and 7.6VDC on both RX and TX. You may need to adjust the TX VCO coil if ...

kcbooboo

They probably say "Not Field Replaceable" just because of the component density, surface-mount technology, and just not easy to replace with a 40w soldering iron "in the field". Those radios are pretty much "replace the entire board" if there are any problems. There's m...

kcbooboo

Electrolytic capacitors that are over 20 years old are always suspect. Tantalum capacitors are known for shorting out - even intermittently. Usually a piece of equipment will have dozens if not hundreds of those. For some reason 10uF tantalums are very common and seem to fail the most. Hopefully one...

kcbooboo

Once you've set the operating frequency correctly on the screen, the carrier frequency ERROR, of an RF signal applied to the RF IN/OUT N-female jack, can be viewed on the MONitor display along with deviation. To use the frequency COUNTER, you need to feed the signal into the separate Vert/Sinad/DVM/...

kcbooboo

Also could be a defective mini-UHF female connector. The inner contact gets spread open by improperly crimped or soldered male connectors plugged into them, and fails to make a connection. Acts as a capacitor. Sometimes another cable will work fine. The only cure is to replace the mini-UHF female co...

kcbooboo

You probably can't fix anything on the ceramic IPA substrate but the surrounding discrete parts might be easy to replace. The style of IPA/REG in that manual is the "old" type. The newer ones use a small RF brick and the majority of the circuit board is the regulator and an interface to th...

kcbooboo

Did you find the problem?

Bob M.

kcbooboo

Additional info: find 6881082E20 in the Motorola MSF section and open the VHF IPA and Regulator PDF file. It has troubleshooting procedures for both assemblies. The test procedure even documents how to put the station into tSt mode. The pot could go open. That's often how they fail. The arm doesn't ...

kcbooboo

1. Sorry. It is documented, although very hard to find, in some manuals, and that IS the procedure to enter power control bypass test mode. In the Motorola MSF section of repeater-builder, search for 6881082E05 and go to PDF page 26. 2. No. The power control circuit, which includes the front panel p...

kcbooboo

The 2nd oscillator in the Spectra RF board is a phase-locked-loop design. There's one and only one potentiometer inside those radios and it adjusts the PLL frequency. The pots can go bad/open, and the oscillator dies or is way off frequency so you receive nothing. Play with that pot a bit. Also read...

kcbooboo

If you go to www.repeater-builder.com, Motorola area, Spectra section, "Radio and Equipment Modification Articles", you will find the 2nd, 3rd, and 4th items to be rather pertinent. In particular you should avail yourself of the recap offers made by AI4JI in the 4th link.

Bob M.

kcbooboo

You can thank Motorola for being so consistent in their cable labelling color codes. That's bitten more than one user.

Bob M.

kcbooboo

Usually there's a white or silver line along the side that marks the negative lead of the cap. In the photo, this line wraps over the top of the cap and is on the side opposite from those yellow connectors. If this is a power supply board, there are probably negative power supplies where the positiv...

kcbooboo

On the A/B/C units, the dummy load, and hence the RF sampling circuit, are all inside the RF input module (A11) where the step attenuator resides. As this is a very well shielded and sealed module, it's not something that can be readily adjusted in the field. The mfgr had test jigs for such assembli...

kcbooboo

The 100w amps can have a DPDT relay installed inside, but a 200w amp might be a bit too much power for that kind of setup. The relay will take some number of milliseconds to activate when its circuit senses RF, and the amplifier itself may start putting out power before or while the relay switches. ...

kcbooboo

I don't know. As the Quantro uses an MSF5000's PA which needs 2-4 watts, there could be an IPA module in the Quantar chassis that amplifies the raw exciter to the level required by the MSF5000 PA. I have no documentation on the Quantro, just the Quantar.

Bob M.

kcbooboo

Add VHF-Lo as a column for the Micor only. Micors tend to send 400-600 milliwatts to the PA. MSR2000 is probably the same as the Micor but I didn't research it. MSF5000, VHF-Hi, UHF (403-474), 800, 900 IPA output is 2-4 watts. MTR2000 and MTR3000 exciter both output +14 dBm or about 30 milliwatts. Q...

kcbooboo

Motorola has used several methods at the mobile microphone to enable coded squelch: The button on the back of the mike... 1. must make contact with chassis ground (a metal clip screwed to a metal chassis). 2. must make contact with a larger metallic outer ring around it (a metal clip that doesn't ne...

kcbooboo

The case is cast metal of some kind, probably aluminum or an alloy. Welding could be difficult. Easier to mill it flat and bolt on a decent-sized finned heat sink.

Interfacing the radio as a repeater transmitter is quite easy. I bet there's at least one article on the web that deals with it.

Bob M.

kcbooboo

According to the service manual, the radio CAN be programmed to turn on and off with IGNITION voltage and it CAN ignore the ON/OFF switch on the volume control. But you have to be careful when playing with that programming because you could get the radio in a state where it can't be turned on with e...

kcbooboo

Bernie found some letters on one connector. They appear to be Omni-Spectra "OMQ" series, which have not been made since the late 70s, early 80s. There may not be anything that will actually fit properly these days.

Bob M.

kcbooboo

Thanks. It looks bigger than SMB but smaller than SMA. Also could be reverse-polarity.

I presume they used the same extender kit on the entire R2001 line, however it's not inconceivable that they used something else on the "D", where so much changed.

Bob M.

kcbooboo

Does DPJ126 or Jry or anyone else know what type of RF connectors were used on the RF boards and motherboard? I'd like to make some RF extender cables so I can align the boards above the chassis. I already have 72-pin and 100-pin extender cards. They look like SMA without the threaded outer part or ...

kcbooboo

Not sure if the radio requires the control head to pass self-tests.

Probably safer to pull the flex cable out of the radio and leave it attached to the control head.

Bob M.

kcbooboo

Could it be a per-channel "Local/DX" setting, like GM300s have?

Bob M.

kcbooboo

I connected the CRT to the CR70 tester per the book, using pin 4 (focus) as G2. I got ZERO emission. I then tried it with pin 7 (accelerator) as G2; still zero emission. I went through the rejuvenate, auto restore, and both manual restore procedures. Still had zero emission using pin 4, but when I h...

kcbooboo

One more quick question. I know the CRT pins for filament, cathode, and control grid, but I'm not sure which is the correct pin or element to use as the second grid, or G2. The Sencore CR70 setup manual says pin 4 which is the Focus grid, but other research has indicated that the Focus, Geometry, an...

kcbooboo

There are vertical and horizontal gain pots on the A2 card that control the overall CRT display. These are separate from the vertical and horizontal calibration pots that are on the A3 or front panel cards. Obviously noise coming through the RF section will raise the baseline. You might have to disc...

kcbooboo

Lynn: I realize it's been a while, but things go slow here. My CRT is still quite dim. A friend had one in the same condition so he bought a rather used (and needing repair) Sencore CR70 CRT tester/rejuvenator. He ran his CRT on that and after a few rejuv cycles, he said it looks like a brand new tu...

kcbooboo

Yes, there's a separate program called TUNER that does all the alignments.

If the programming software is newer than a few years, remember that it only allows narrow-band (2.5 kHz) programming unless you've got the special entitlement key to allow 5 kHz deviation.

Bob M.

kcbooboo

The supply takes incoming 120VAC and reduces it through a transformer and the four stud diodes to create "RAW DC" that's in the 12-16V range. The incoming 12VDC line joins up at this point. Then they use the RAW DC to run a 20 kHz oscillator and some switching transistors that feed a secon...

kcbooboo

Easy is a relative term. Pull the wireline card, pull the station control/exciter/receiver modules, unplug some connectors, cut some ty-wraps, remove the screws holding the rear cover on, remove any remaining screws holding the backplane to the chassis. If this was my station, I'd do all of that. I ...

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