2 antennas and 2 amps at the same time?

[209 first class]

on occasion i can hear someone on the vertical i cant hear on the beam and the reverse happens of course. but what if i took a t connector out of the radio, and fed separate amps, one driving the vertical, and one driving the beam? im not sure if the impedance will be cut in half meaning each amp might see 26 ohms, or if it will stay the same. i guess it couldent hurt to try it on recieve, just a t connector onto the 2 antennas ? i could slap the mfj analyzer on there too. i sense a trip to radio shack in the near future unless someone has heard it tried and failed.... 209

[80 meter man]

I wouldn't do it. It's inevitable that one amp/antenna system will have either more capacitance or inductance. The output power will be split between the two systems and the impedance will drop to 25 ohms. Sounds to risky. You might end doing damage to some of that nice equipment of yours. How about just putting in an A/B switch? That way you can switch between the two saftly.

[209 first class]

hi, i have the antenna switch, my idea was to run the vertical antenna and the horizontal beam at the same time each powered by thier own amp. any mismatch i assume would happen after the radio where it splits in two, and not at the amplifiers. i will grab a t- connector and put them both on the analyzer and listen to both at once and print what i find. if it seems favorable, or possible, i will try it with 2 pill amps on each one with an old radio. 209

[Speedy]

Put the T in after the a single amp?

Speedy

[drdx]

I think the amps may harm each other being in proximity to that much RF from another source, but I've always wanted to try the same deal trying to run 2 identical amps into 2 nicely spaced mobile antennas, same concept. What you're after here is polarity. Maco used to make an antenna switch that would allow you to run both horizontal and vert on a beam, such as a moonraker or whatever, at the same time, and I'm sure others do as well. You'll want to make sure your coax runs are the same length, etc. or you'll cook up a weird pattern I'm afraid. How about the circular polarization deal, I'm foggy on the topic, but I think feeding 2 like that out of phase produces that type of effect??? Good topic. -drdx

[MOONSHINER]

I would just get a dual polarity beam, or like I do, use a antenna switch from beam to ground plane, that way you are covered no matter what. put the switch after the amp. you will still have to have to runs of feedline after the switch.

[Night Crawler]

Run the output of your radio through a short jumper to an antenna tuner
the output of the tuner to the input of the T each side of the T to the amps that way
you can match the impedance from your radio going to the two amps.

[209 first class]

speedy: i meant put a t after the radio, then into 2 separate amps and powersuplies and antennas (horiz beam and vertical 5/8 wave.). drdx: yes i had thought of phasing problems, there may be weak spots here and strong spots there.i didnt know u could run horizontal and vertical at once, i never saw those maco boxes. getting a dual polarity beam is not in the equasion, i just put up a flat 6. i was looking to combine the best of both worlds (vertical and horizontal) to come out above what a normal vertical beam can do. in the world of audio reproduction,(not that they are anywhere alike, but the theories might overlap) 2 ten inch speakers playing 25 watts will be louder than one playing 50 watts. there are also gains in efficiency and linearity because each part only works 1/2 as hard, but the sum is more than the speaker with 50 watts. there may be similar gains with antennas and amps. i got the t connector, i will try to see how it recieves against one antenna by itself. truckers co phase thier dual antennas, so i dont see why it wouldent work. i know co phased antennas need to be tuned exactly alike, if need be i could put an antenna tuner on one as nightcrawler suggested, and match it to the other. but- seeing as i will have separate amps driven by one radio, i do not think the mismatch will harm anything. if anything it may just not work well. someone must have tried this before somewhere

[drdx]

Hey, keep in mind on the trucker cophasing deal, they use 75 ohm coax. You could certainly use a tuner, but you will lose a little efficiency in that the tuner is just fooling the transmitter and not actually fixing the problem, but the increase might be worth it if it actually works. Keep in mind, double the coax, double the coax loss too. Have fun with it, that's why we're here. -drdx

[209 first class]

with the t connector,(two antennas on one radio) the mfj analyzer gives kinda wacky readings. its 1.1 at 28.16 mhz. its 2 or just under across the cb bands. on receiving, sounds like there is some improvement, when i connect the beam, the noise from the vertical dissapears, and the meter readings are slightly higher than each antenna alone. hmm. 209

[209 first class]

i listened to it last nite, some stations were weaker and some were stronger with 2 antennas instead of one.i ended up connecting the t connector to two amtenna switches so i could compare them. must be the phasing and the fact that they are far apart. i might have had different results if the vertical was mounted on top of the beam. it was fun to experiment with :D

[MOONSHINER]

I think I understand what you are trying to do, but, for local talking most people use a vertical antenna, for dx flatside rules. So, why not just use an antenna switch box and switch between a vertical ground plane and a flatside beam?? That way you dont have to do any co-phasing, run two amps, etc. You would run radio to amp to meter to antenna switch and then out to your antennas.

its easy to compare signals that way, all you have to do is switch back and forth.