Antenna for AM60-550

[Thibault]

Hi all, I just got a Blender Tongue Am60-550 to feed my vintage TVs to which I connected a small and simple fm antenna.

I am very, very new to rf and the first things I noticed are: I can’t seem to get vhf to work (that’s ok, I ended up using UHF channels instead) but more importantly my vintage tv will barely get any signal if I am further than 20ft (snowy picture and no sound).

Would anyone have any recommendations for a good vhf/uhf antenna?

[vortalexfan]

Using an FM Dipole Antenna is your first mistake, an FM Dipole antenna is designed to only pick up signals in the 87.5-108 MHz Frequency range and the only TV Channel that is within that frequency range is Analog VHF Channel 6 on your older NTSC Television Tuners (the old Turret style and veractor style tuners where you have a fine tuning function for the VHF band) other than that a FM Dipole Antenna is basically worthless for TV Reception use.

I would think that any old Standard TV Top UHF/VHF Antenna made within the past 50 years would work for your purposes (if its just being used to pull in stations for a converter box that is feeding a signal for the Agile Modulator), as far as sending a signal out from the agile modulator, I think they generally have their own built in amplified antenna that can radiate out a signal for a short distance (think of how a WiFi Router works.)

I hope this helps.

[jhalphen]

Hi to all,
Hi Thibault,

Please have a look at Phil Nelson's page on using a Blonder-Tongue Broadcast modulator like yours for home broadcasting.
If you scroll down the page, there is a description of a dipole antenna with the correct length for each wire of the dipole for US VHF channels 2-13.
Phil gets good TV signal coverage over his large house, so you should too :

https://antiqueradio.org/HomeTVTransmitter.htm

You mention getting only UHF to work. Do you have the Blonder-Tongue user manual which gives the position of the dip switches to program the channels?

I suppose you don't have the latest model with red LED channel display & up/down pushbuttons.

Best Regards
jhalphen
Paris/France

[Electronic M]

On that page Jerome liked, the author Phill links to a good YouTube video by Shango66 that shows the process for making a tuned dipole.
The formulas for it assume you are matching to 50 Ohm coax instead of the 75 Ohms that the blonder tongue and most cable and consumer TV gear uses. He uses an expensive SWR meter to tune the antenna for 75 Ohms but you can get the same result without it....
From my college antennas elective Iearned that the formulas for 50 and 75 Ohm dipoles have a linear relationship such that if you calculate the percentage of the calculated length shango had removed at the end, then remove the same percentage of length from an antenna of a different channel you will get the same correct tuning.

I've been using that method and I can transmit a block with my AM 60 on CH7 at full power.

[Thibault]

Vortalexfan this makes total sense as to why I could not get VHF to work!

jhalphen, I do have the one with the LED channel display. I'll admit my mistake and shortcoming: I came to buy the agile modulator because of Phil's post, but I was so eager to try and overconfident that I skipped the antenna part of his post (facepalm).

I believe i have everything I need in-house to build my own antenna using Phil's recommendation!

Thank you both, i am very grateful for this helpful community!

[Thibault]

Thanks Electronic M for the additional color and advice!