looking for manual and schematic for an LPB FMS-2000 cable modulator also
looking for manual and schematic for the 1 watt amp lpb sold to use this
with radiating cable.
looking for manual and schematic for an LPB FMS-2000 cable modulator also
looking for manual and schematic for the 1 watt amp lpb sold to use this
with radiating cable.
i'd ask lpb but we all know what happened there. sad to see a once great
comapany gone like that.
I have been in touch with several former staff at LPB last week, and a couple of them have promised to post up docs here, and to answer questions. They are just as sad to see what the last owner did to LPB, one watched almost 50 years of pictures, technical data, repair manuals & more, get thrown in a dumpster. A previous owner said that some stuff was hauled across the scales for scrap. What a waste! Those of you interested in chokes & caps to change the band on LPB AM transmitters, stay tuned, will have some great news for you soon, thanks to an LPB sales guy. 🙂
Tommy J.
Bellville Texas
that should have never happened to the company. there was no other reason beyond the typical mismanagement present in corporations these days.
here are pics of the internal circuitry
Ok..so what are you attempting to do..re-frequency or is it in need of some repair?
In reference to a post within this thread back in Nov of 2011...about the former LPB folks posting here with info, doesn't seem like its going to happen.
A shame because there are still many LPB units out there in use and many of us who do have LPB units have had to scratch, dig and claw for information, even as far as dissecting units down to the last nut and bolt and spending weeks on end hunting down toroid cores for the filters.
I even went as far as having spare PC boards etched by taking the original boards with nothing mounted to them, and photographing them on 35mm film, taking the negatives and having etch master templates created. That was no cheap venture either!
But these LPB units are worth it simply because they are built like super tanks and if taken care of and run properly and well maintained, will outlast the bigger more expensive transmitters.
If I could, I would start an after-market LPB parts and repair company to continue support of these excellent devices.
As long as there are units in use out there, there will be an on-going need for service, information and spare items.
As to how LPB got trashed by the new owner...well perhaps that owner should have invested in Dixie paper cups. Plenty of throw away product there!
RFB
for one trying to figure out the specs on it. power out etc. also want to put a better SG on it that has balanced inputs and better filtering/limiting.
From the photos, it appears to have no more output than a typical video cable modulator, around 20mW..maybe a little less. Cable head end's don't need a whole lot of juice piped into them.
As seen in a couple of the photos, there are small signal matching transformers like those found in 75-300 ohm baluns.
It also appears to have an elaborate filtering system along the entire signal path..including the IF section. Necessary to prevent co-channel interference and very obvious why that unit is using IF for it's signal generation. Not a typical direct FM oscillator or PLL transmitter.
Like I said earlier, LPB made their gear like tanks and built their units to meet and more often exceed FCC specs, basically over-engineered to last and they do.
For the SG, it appears you could inject the MPX at a couple of places. There should be a "loop" option for that on the back. Simply remove the short loop coax and plug in an external SG's MPX output into the MPX input at the loop.
Looks well taken care of compared to a few I've seen over the years. Should be a great performer as it is.
RFB
here is the spec sheet on the fms 2000
http://www.amt.com/images/products/DHM-332_AMT.pdf
from john devecka....
"The FMS-2000 was manufactured for us by DX Antenna in Japan. I believe it
is currently available in the US through AMT in Florida with the model
number DHM-332 so you should be able to get a schematic from them. It's
an excellent unit and it's pretty rare that anything goes wrong. I've
been running one of there stereo TV modulators 24/7 for 9 years without
any issues. The RB-1 amplifier that went with it was based on a
Mini-Circuits 1w linear amplifier. I don't recall the model number at the
moment, but a search of Mini-Circuits catalog should pull it up. Service
for the amp can be obtained through Richard Burden, Burden Associates in
Los Angeles. [email protected] or 818-340-4590. Dick used to assemble
those amps for us so I'm sure he can fix anything you need there. Usually
the only failure on these units was from a failure to properly connect the
50ohm load termination to the radiating cable prior to powering them on.
"
so if anyone finds these now we have info on the fms2000 🙂