Batboard

This is a battery revert 24V/12V dual voltage supply. I don't see a manual for it on Repeater Builder.

What I need to know is, how does the battery connect to it? There is no on-board cutover relay like on the 12V supplies, but there is a 1.5' pigtail with orange and gray wires terminated in a 3-pin Molex plug coming off the filtered 12V side that I'm guessing goes to a normally-closed relay, and a second set of screw terminals with a single white wire also connected to filtered 12V. So..
-Do I use 24V batteries or 12V?
-Do the batteries connect across the 24V PA terminals, or the second terminal with the white wire?
-Is the orange pigtail for an outboard cutover relay?

TIA

On the 14V supplies, there is no cutover relay; the batteries connect to the raw 14V supply at the same place where the PA connects. The supply float-charges the batteries and they act as a big capacitor/regulator when the station keys up.

The relay on the single-battery supplies is an overcharging cutout relay. They don't switch the battery lines on and off.

Unfortunately the manuals don't show where the batteries connect on a 28V supply, however I suspect that you need two 12V batteries outside: one from ground to +14, and the other from +14 to +28. The 28V is only used by the VHF PA; the RF Tray and anything else only needs 14V.

Life is simpler on the 100w MTR2000 stations; two 12V batteries connect in series and feed 28VDC to the station; the PS regulates this down to 14V and 5V. I suspect the MTR3000 is similar. On the MSF5000, the 14V and 28V supplies come from different windings on the transformer and there are no regulators; the ferro-resonant xfmr takes care of that.

If you DO figure it out, write something up and perhaps it can be added to repeater-builder.

Bob M.

kcbooboo wrote:On the MSF5000, the 14V and 28V supplies come from different windings on the transformer and there are no regulators; the ferro-resonant xfmr takes care of that.

That part I did figure out from the manuals: they do come from the same winding with 12V coming from a center tap. The 24V legs go to a bridge rectifier with - going to chassis ground, and the center tap provides 12V+ with chassis ground and no additional rectifiers. Voltage adjust on the battery revert station is handled by a large choke coil connected across the ferro-resonant capacitor; a pair of MOSFETs in line with the choke provide adjustment and are driven by the trimmer pot. Take that coil out of line and the 24V side will swing all the way up to 36V.

Anyway, it's a moot point since the <expletive> RF board in this station is dropping transmit audio after a couple hours of operation somewhere in the transmitter chain. Back to the drawing board...

I suppose you'll have to "divide and conquer" to find who's losing the audio. Most of the work happens in the SSCB and TP4 has the audio where the audio leaves the board. Lots of connectors later, it gets to the Uniboard in the RF Tray where you've got the modulation compensation circuit, then the audio feeds the TX VCO. Things inside the RF Tray do heat up a bit and with no ventilation holes, I'd suspect something there before the SSCB, but I've been wrong before. Reseat all the connectors, then pray.

Bob M.

SSCB/TTRC have been swapped with known good parts to no avail. ModComp sounds suspect. I hope it's not the VCO 'cause we both know how scarce VHF MSF parts are.

One interesting thing I did notice.. both the uniboard and the IPA have more in common with an 800 station than UHF.

There were two styles of IPA/REG assembly. One has the REG parts thinly spread out around the perimeter of the board, and the remaining space is occupied by a discrete-component IPA. The other uses a small 5-lead RF brick for the IPA and the remainder of the board is a very roomy REG circuit. Either version could be used on any band station. I think the ones with the RF brick are newer.

The Uniboard is essentially the same for VHF/UHF/800 MHz. A few component values are changed. The 900 MHz Uniboard won't have the 14.4 MHz reference oscillator as that signal comes from a separate and more stable reference oscillator, and the IF filters will be narrower for 2.5 kHz modulation acceptance. There's also some additional circuitry to support the HearClear and Flutter-Fighter that are only found on 900 MHz. The SSCB is similarly endowed: models for 900 MHz have the HearClear stuff and deal with lower deviation levels.

All you can do is connect a voltmeter to the MOD Input on the VCO to see if audio is reaching it or not. Attach a small wire to that pin and bring it out through any opening you can find in the RF Tray cover, then seal things up so it'll get hot again. Keep moving the wire back towards the SSCB until you figure out where you're losing audio. There's not much in the VCO to go bad except the varactor used to modulate it.

Since I'm a gambling man, I'd put money on audio dying inside the SSCB.

Bob M.

Swiped these from a certain popular auction site. This is the same exact power supply I have.
http://i.imgur.com/vD6Ko.jpg
http://i.imgur.com/kKj95.jpg
The two large capacitors on the left are the 24V supply and the two smaller ones next to it are the 12V supply. Both are driven by the power control pot on the distribution board. The ferroresonant cap is the small one at the top and the ferroresonant choke is underneath the distribution board. This one has the switching relay and battery wiring intact, unlike mine.. I suspect you're right about the battery supply being split.

I looked in my "Power Supply Service Manual" that's impossible to make much sense out of. They list two dozen TPN model numbers, then you have to figure out which hardware kit, which wiring kit, which board kit, goes with it, then find those sheets elsewhere. I found exactly one 28V supply, the TPN1271, and the photo of it doesn't show any mechanical relay at the top under the regulator board. Unfortunately none of the wiring diagrams show the connections to the batteries; everything ends at the edge of the chassis. It does seem that they use a bridge rectifier to develop 28V, and get 14V from the CT of the xfmr.

The one bat-revert supply I ever encountered was a 14V supply for a UHF station. The battery leads were attached directly to the terminal strip where the PA was connected.

Bob M.

kcbooboo wrote: The one bat-revert supply I ever encountered was a 14V supply for a UHF station. The battery leads were attached directly to the terminal strip where the PA was connected.
Bob M.

That one is a regulated power supply that is battery back-up. I have the roadmap somewhere in the old archives.

motorola_otaku wrote:Swiped these from a certain popular auction site. This is the same exact power supply I have.
http://i.imgur.com/vD6Ko.jpg
http://i.imgur.com/kKj95.jpg

Looks like the MSR station power supplies.

Are you still working on the MSF1271A? I can scan a copy of the manual if you need it. The batteries do indeed go directly across the 12 and 24 volt outputs on the supply, which can be a bit of a problem. The 12 Volt supply is properly regulated, but the 24 Volt supply is kind of "along for the ride". I got around the problem by moving the 12 Volt cooling fans up so instead of being fed from 12 V to ground, they are now on 24 V to 12 V. Two fans load down the upper supply and prevent it from frying the upper battery.

I'm also in the process of building a slightly more sophisticated battery revert scheme for all the club repeaters, with the hope of getting batteries to last longer then they have been.

Actually, no, I did get that part figured out.. but I'm sure Bob and Repeater Builder would appreciate the manual scans.

I also pinned the audio issue down to a pair of bad ICs in the mod-comp chain. One was a common part available from DigiKey, the other had to be salvaged from an 800 MHz parts board. My notes are at the house so I'll have to post the specifics later.

Then I ran into an issue with the PA not putting out full power at 147 MHz. Turns out there are laser-etched tuning strips on the power hybrids that "peak" the power output to a segment of the 146-174 rated bandsplit. A little work with the conductive ink pen fixed that, but again my notes and pics are at the house.

And finally, after all that, the station only worked for about a week before the power control circuitry barfed. Now you can only run it up to about 10W before it goes into PA fail. After that I just gave up and pushed it off to the side.

Doggone it I lied!!! I don't have the real documents for the TPN1271A. Had to dig thru the pile of manuals and notes to remember - after all it's been almost two decades since I worked on that particular power supply. After a whole lot of circuit extraction and comparison, it became apparent that the TPN1271 is just a TPN1260 with the voltage regulator board from an TPN1185. A simple case of Motorola mix-and-match!

I understand your frustration with the PA. Was recently working on yet another VHF MSF5000 that I want to rotate into service when one of the infamous bypass caps on the IPA went up in smoke. In the process of performing surface mount surgery to replace the bad cap I did something to the Uniboard. Now instead of a an error message on startup it's doing endless reboot cycles. I have what I hope is a spare Uniboard from a parts machine with a broken power level pot and munched coax cables. Will have to swap parts around and see what happens. Will also have to keep hunting for more MSF pieces-parts.

Too busy to work on it now, might be able to scare up the time in late December....

Good luck with your PA!

Regarding the supply: I found the relay. It was in an addendum to the PS manual. It connects through a 4-pin connector to the charger board, which drives the coil on two wires and looks at the two contacts on the others. No clue as to its function or where it fits into the bigger picture. Still no overall station and battery wiring diagram; that would have to come from a service manual. The one I have doesn't have anything about battery-revert; the only PS is just the stock 28/14V supply.

The current PS manual is horribly difficult to use. You first look up the TPN number, then scan across and find one page for the photo that identifies the major parts, another page that's the "hardware kit" which is actually the overall schematic, another page that's the 28/14v battery charger kit which is the circuit board and its schematic, yet another page for the parts list for that board. I guess they took every variant they could find and put it into one hard-to-use manual. Most of the pages are 11x18 fold-out which makes them hard to scan.

Bob M.