On Phil Nelson's site, he has an article about setting up a home TV transmitter system using a wonderful device called a Blonder Tongue Agile Demodulator AM60-550A. Does anyone here use this beastie, & how hard is it to set up ? I've noticed there are a whole SLEW of these Agile Demodulators, is THAT particular one model the only one a fellow can use ? I mean, I see AM50s & AM60-450A, would either of THOSE work ? Would like to be able to run more than one or 2 of my half-a-jillion TVs-Think it might be kinda fun to Impress the Natives around here...Are there OTHER ways to run a whole bunch of yr TVs simultaneously that a fellow can use that DON'T cost 2 Arms 'n' several Legs...(grin)

Sandy, I have two of them, they aren't hard to set up at all but I haven't had much luck getting them to work without some faint rolling bars in the picture.

CTC17 made me a nice properly matched antenna to use but I haven't been able to set it up permanently yet and give it a real test.

Sandy-

You need to be sure to get modulators, not DEmodulators (maybe that was just a mistake in the description). The '450 versus the '550 just cannot go as high in frequency (but we will not care for our use with antique TVs), and the AM40 has lower signal output versus the AM60, which should only be important if you do want to try using one of these devices as a true over-the-air in-house transmitter (then get the AM60-450 or AM60-550). Phil's site is a treasure of great information. You can either try this "in-the-air" method with antennas on each TV, or put a multiple-output splitter on the output of the modulator and run coax to each TV, with a matching transformer on each one.

Eric, I may have had that problem too (I have not tried one of my modulators in a while), and one trick may be to put a "grounding adapter" on the modulator's power cord. This is the gadget that has a three-prong AC outlet on one end and a two-prong plug, with a pigtail or metal loop for the ground (that in this case you will NOT connect). The idea is to not use the grounding connection on the modulator's cord, to avoid a ground-loop problem that can happen when commercial items like the modulator are mixed with consumer two-prong items like a DVD player or digital-TV tuner.

I use about 5 VCRs and a big rats-nest of coaxial cable, switchers, spliters, and 75-300 ohm matching transformers. This gives me the ability to switch any of 6 different sets independantly between four different signals.
Or at least that is how it was. I'm presently shifting around my entire entertainment setup so it may endup a little different.

I've got a gagle of video devices connected to my VCRs, not to mention analog cable so I have a plethora of content to entertain my self with, though if I run more than three of my color sets at once I trip the breaker so I can't take full advantage of this setup.

Tom C.

perhaps that ground loop is the reason it works fine when directly connected to the set with coax? same deal here, slow moving hum bar when just antenna is used.

Hi Sandy, Hello to all,

The secret of the Blonder-Tongue AM60-450A popularity is it's phenomenal Max RF output power (for a modulator).

It outputs +60dB/mV which equates to 1.024V on a 50 Ohm load and nearly 21mW out the antenna - enough for 'round the appartment "Broadcasting" with a dipole providing the conditions are not too stringent.

Most other Blonder-Tongue RF Modulators output a lower and more "reasonable" +40dB/mV which equates to 0.032mW of RF power, not enough "oomph" to Broadcast anywhere.

The lazy man's solution is to trot over to e-Bay's RF Amp section and select a model to play the role of RF Final Amplifier. There are nice models by Mini-Circuits & Avantek (now defunct) with Class A linear amplification from 1-10MHz to 200, 300MHz or 1 GHz with output powers ranging from 50mW, 100mW up to half a watt or more. Purchased second hand for low prices, these are really fun modules to experiment with. Caution! anything above a few milliwatts output power must absolutely have an antenna connected before power is applied or the output stage will fry in milliseconds.

http://business.listings.ebay.com/Parts-Accessories-Plug-Ins_Amplifiers_W0QQfclZ3QQfromZR11QQfsooZ2QQfsopZ2 QQsacatZ25392QQsbrsrtZdQQsocmdZListingItemList

Personally i operate 2x 100mW TXs in VHF 625/PAL and 525/NTSC with no problems whatsoever (may i say 10 years now). Also allows you to operate mini/micro TVs off their internal whips without dragging a cumbersome ATSC box + yet another power supply cord.

Additional advantages derived from using second hand Broadcast gear is that the output signal conforms to the Vestigial Sideband RF Broadcast standard whereas all consumer modulators output both sidebands with equal intensity.

In practical terms, this means that you could operate several modulators staggered to different channels leaving only one free channel in betweeen, such as 2-4-6,... - with a consumer modulator, at least 2 channels interval is necessary to avoid interference.

Of course, never use a channel broadcasting a legitimate TV content or anything else. Over here in Europe, VHF Band I is totally abandoned and Band IIII is on the way out except for DAB digital radio in some countries (UK, 220MHz band). TV on UHF rules supreme...

See the Blonder-Tongue spec sheets for the AM-60 Series attached to this thread - (can't post twice the same document)

http://videokarma.org/showthread.php?t=234563&page=2

Best Regards

jhalphen
Paris/France