Small VHF Transmitter

Would this do?

A stand-alone A-V modulator unit from the VCR era gets you to channel 3 or 4; a good antenna-distribution amplifier makes that transmittable; a vertically mounted folded dipole antenna allows you to match with a balun. All often available at thrift stores etc. I have used this to re- transmit to a small area in a remote location, it worked fine.

Thank you for that link! It is a good start.

But, by the time I got out of there, I was well over $400 - not what I woul d care to spend for something that would get used twice per year for a hob by I do not have. I am trying to be a full-service OTA provider for the goo d of the club, and to help the other vendors as I do with the AM & FM-stere o transmitters. UHF TV would close the loop covering all the relevant recei vers and tuners.

Thanks again!

Peter Wieck Melrose Park, PA

I have everything on that list in-hand but for an A-V modulator and distribution amplifier. I expect that those things are not hard to find with timing being the only issue at this point.

Thank you!

Peter Wieck Melrose Park, PA

A few years ago, I used an RF amp from these folks and it worked well. In the VHF range, the amps they have are relatively low power 1-3 W. Would something in that power range be sufficient?

Blonder Tongue and Holland agile or fixed channel modulators sell cheap on Ebay. They put out enough RF that you may not need a power amplifier. I've bought them for $15 plus shipping. R.L. Drake also built them. Pico, Microdyne and others built them for MATV headends and they are all are basically obsolete since 2009. RCA, Scientific Atlanta and Phasecom built them for CATV headends. These sold new for thousands, but there is little to no marlr them.

Some can also put out their Aural carrier on the old 49 MHz FM band. You would need a trap to kill the video carrier.

There are lots of five for $30 on Ebay, right now. They are without the power supply, rack and combiner, but you only need power for one of them. I don't know what channels they have left, but the seller is E-cyclePro. They often have these items.

Holland-HPM55-Audio-Video-Modulator-Tested-Commercial

If you want to drive multiple lines, there are sometimes one in, 16 out broadband distribution amplifiers for under $50. With the high output level of a MATV modulator you could use a four way splitter, each split four ways to drive up to 16 TVs without an amplifier. That would require running a lot of RG59/6/11 coax. With the amplifier you could scatter a few antennas around and use rabbit ears on the TVs with a lot less coax.

I have a new, in the box Tradewind Rack Mounted Distribution Amplifier for $35, but i don't think that you really need it.

Thank you! I am going in this direction, with thanks to a certain individual who happens to have such a device, and is willing to pass it along.

Peter Wieck Melrose Park, PA

See if you can find a good image of the old test pattern and burn it to a DVD. That will help people see how sharp the image really is. It will also show poor IF alignment that was done with crude Sweep/Marker generators rather that a multiburst system.

Let me know if that doesn't pan out. I am familiar with a lot of brands and models of modulators. I have a nearly complete analog headend system, in storage. I just need a couple full height relay racks, and dipexers for 60 channels! :)

At one time my job was to repair headend equipment for a top 100 MSO cable group. We also up linked WGN, WOR and operated the first Electronic Program Guide on a subcarrier on our WGN transponder. We also had WFMT on another WGN subcarrier.

Sigh. That was 35 years ago. I did over 10,000 repairs, in four years including microwave equipment the OEMs refused to support.

Never piss off an Engineer!

They don't get mad.

They don't get even.

They go for over unity! ;-)

I am sending Peter a Blonder Tongue Agile Modulator. Model: AM 40-450 Stock No. 59406. Complete with a manual for setting the output channel dip switches.

Nice. It would appear that you are not the prick most people in other hemi spheres would have us believe.

Many many moons ago when cable TV was still analog, I put an A/B switch on the main line of my cable and used the B side to feed my distribution amp i n which the output was connected to a set of rabbit ears and the A side to feed the cable box. That setup broadcast the whole VHF spectrum to any TV in the shop I would put a clip lead to. One day the cable guy comes in - th ey had been driving around "sniffing" for leakage, and my store was a real hotspot. He thought I had an open ground, but I told him I knew where the bad crimp was and threw the switch to A and the problem went away. The nex t day I went back to using the B side and a couple of months later they cam e in again, so they must have sniffed routinely , so I abandoned the plan. I should have tried broadcasting the output of the box alone - maybe they wouldn't have bothered me if it was a narrow spectrum.

That is a well made Agile modulator with a decent VSB filter before the upconverter. My comment wasn't meant to imply that he wouldn't get a modulator, just in case something happened to it. Too much stuff is being lost or damaged in shipment these days. Fedex just lost a Sadelco FSM of mine. The love to leave my packages at similar addresses on other streets. Some of the old analog FSM have a crude but useful Spectrum analyzer mode built in. Peter might even want more than one modulator, on adjacent channels, to show how old TVs deal with Intermod and Co-channel interference.

I finally have a HP 1.3 GHz counter to fill in the gaps in the programming chart for that model. I believe it goes down to the T channels, that were used for reverse feed but I can't access my outboard drives until I complete electrical repairs. An open neutral from the pole pig fried most of my equipment, and all of the surge suppressors on one phase. I currently have one working 20A single phase circuit and a lot of dead equipment after that phase went over 165 volts.

As usual, the utility just rolled their eyes when I told them the neutral was open. They sent an automated call just before midnight, canceling the service call, since their so called 'smart meter' reported that I had power. They don't report an open neutral. I had to threaten to report them to the PUCO when I called back, before they actually sent out a truck. Once again, I got attitude, then the lead tech saw the bare neutral arcing where it had broke. That drop was installed in 1964.

Signature required makes a lot of difference.

That stunt could have wiped out communications for emergency vehicles on the VHF high band, the two meter ham band and airports. You could have indirectly caused people to die. We had people do that in Apartment buildings, near Cincinnati. We had to install monitors in all of our trucks to find them as soon as possible. If the FCC got involved, it could have lead to time in prison. Cable TV uses those frequencies on a shared basis, under the condition that leakage levels be maintained. On big problem was morons slipping 300 ohm flat antenna cable under a carpet, to move the TV to another location. It could be detected from blocks away. Our sniffer system was outdated, but the video carrier for MTV was on the right frequency so we could still use the receivers.

I was told it was being shipped by USPS. They told the seller that they had over a two week backlog, and to use anyone else. I wasn't given the choice. Fedex often delivers after 9PM, which doesn't help. UPS often gets here after dark, as well.

Yeah. Instead of an incorrect delivery, you get a note in the mailbox saying "We tried to deliver but no-one answered the door. Please come and pick it up at our warehouse" (40 minutes drive away). I've watched couriers delivering such notices, rather than walk the ten steps to the front door and ring the doorbell.

CH.

Thank you all for the information and suggestions. I will be able to test t he concept with our big Sony CRT type TV we brought back from Saudi as it h as an on-board OTA tuner with NTSC/PAL/SECAM compatibility. So, I will repo rt back when it arrives from Ranger, TX. And. after Kutztown, I will repor t on range.

Thanks again!

Peter Wieck Melrose Park, PA

One thing that wasn't mentioned. The output level is +35 to +45 dB. That can damage some TV tuners. A pair of 20 dB pads in series will give you an output of -5 to +5 dB which is the normal range for tuners. Even when connected to an antenna, you may want one 20 dB pad to limit the range.

The only 75 ohm pads that I have on hand are 6 dB. If I had any 20 dB available I would send you some. It would take seven of the 6 dB pads to get the output into the normal range. Maybe Jeff has a couple that he can spare,if you don't already have them?

A last resort is to make your own. 20 dB per stage is the most you want to homebrew, per stage. Above that requires careful positioning of the leads, and extra shielding.

RF Cafe has an online calculator for both Tee and PI types. Set the input and output both to 75 Ohms, then enter the attenuation, per stage. Then click the 'Calculate' button. You are probably familiar with the formulas but some of the others who are reading the thread, aren't.

I have a Fedex account. They USED to email me the day before a delivery was made. They don't even do that, now.

Thanks for the tip. I am not about to connect the TV directly to the modula tor it will be two floors and about 100' away by direct line, and the outpu t will be via rabbit-ear antenna. At Kutztown, I will be expected to cover a bit over two acres, and I will be feeding, almost exclusively, tube-based vintage devices. But if I overload the Sony, I will snag (an) F-connector pad(s) as needed.

Thanks again!

Peter Wieck Melrose Park, PA