Question about 2 meter amplifier used with dual band Mobile
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Does it have a duplexer attached ?
n5ims
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That would depend on the design of your amplifier. If it has a pass-through when off as part of its design, you should be OK transmitting on UHF with the amp powered off. Less likely is your amp having the ability to pass UHF signals through while powered on. With the popularity of dual-band radios you might get lucky, but I wouldn't count on that. Your answer is something you should seek from the amp's support line since they would be the ones that know (or can ask their engineers for) the answer. Posting the amp's make and model here may give you a better chance of getting a more accurate answer on these forums since some ham just might have the same setup and tried it out.
NZ4ZN
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I would agree, there are many amplifier models and the instructions in the manual or looking at the schematics should address this.
I have an RFC 2/70 amplifier/pre-amp for 2 m and 70 cm that I use with an HT. It provides a pre-amp for incoming signals and a power amp for outgoing. 5 watts in and 20/30 watts out, depending on band. It has one input (radio) connection and one output (antenna) connection and works as follows:
1) When the output amp is turned off, the output of the exciter is a direct pass-through on both bands.
2) When the output amp is turned on, the amplifier automatically switches bands to match the TX frequency and amplifies the outgoing signal.
3) When the pre-amp is turned off, the incoming signal is passed directly through
4) When the pre-amp is turned on, the incoming signal is amplified
N4KVE
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I have a TPL 5 in 100 out UHF amp. The amp has no switch, but I used an on/off switch on the power cable. When the power to the amp was off, the 5 watts from the radio went right to the antenna. By turning the power on, the amp now powered up, turning 5 watts into 100 to the same antenna. A better amp will recognize the VHF signal, & amplify it, but sense a UHF signal, & say that's UHF, & I'm a VHF amp, so since I can't amplify it, I will allow it to pass through.
NOT A LOT....
50->100w is 3dB. A S-meter unit is 6dB. So most likely nobody would see the difference.
As for the original question, depends on the amp but you can easily do it with a pair of duplexers.
440 will pass through duplexer 1 on the 440 side and back into the 440 side of duplexer 2 and to the antenna. 2m stuff would go through the 2m side of duplexer 1, into the amp, into the 2m side of duplexer 2, out to the antenna. ie: Duplexers are splitting the coax lines in two.
There will be loss, you'll have to see how much, and account for the extra connections etc.
But that's just all for information; 50->100 would not be worth it. 50->300 would be a little over one s-unit and might be worth it, but honestly probably not worth the complication and loss on the RX side.
NZ4ZN
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As posted above, not much practical difference. IMO, it would only be a benefit if you had repeaters just a little too far for full quieting, since it would probably make a scratchy input signal clean up a little.
KC4RAF
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Just as posted.
If you have 50W going to a really good mobile antenna, you more than likely hit repeaters at quite a distance. As the old adage goes, "the antenna is what makes the radio".
If you have 50W going to a really good mobile antenna, you more than likely hit repeaters at quite a distance. As the old adage goes, "the antenna is what makes the radio".
I've got a Kenwood TS-2000 that I use for VHF/UHF. It's capable of 100 Watts on 2 meters. (FM, SSB and CW)
I've gotten local signal reports while transmitting on FM at 100 Watts and then 50 Watts to a dual band vertical antenna mounted on my tower. Most people can't really tell the difference. (As pointed out, theoretically, doubling the power will only result in an increase of 1 S unit on the receiving end).
Because of this, I only use 50 Watts when on FM.
I've gotten local signal reports while transmitting on FM at 100 Watts and then 50 Watts to a dual band vertical antenna mounted on my tower. Most people can't really tell the difference. (As pointed out, theoretically, doubling the power will only result in an increase of 1 S unit on the receiving end).
Because of this, I only use 50 Watts when on FM.
Oops delete, ignore etc. dupe post khaytsus said the same thing.
Since your radio has a single antenna connector you could purchase 2 diplexers and connect the amplifier between the VHF ports of each diplexer.
Then connect a short coaxial thru connection between the UHF ports of the diplexer.
This way you can leave the VHF amp on at all times when switching between VHF and UHF.
With the typical diplexer you will have about .25 db insertion loss on each diplexer so your amplifier output power (50dbm, 100 watts normally) to the antenna will be closer to 49.5 dbm or ~89.125 watts.
You will of course have a similar combined .5 db loss on the UHF side.
I use this method with a dual band 2meter/220MHZ HT and a 220 MHZ amp and 2 homemade diplexers feeding a 2/220 dual band mobile antenna.
Since your radio has a single antenna connector you could purchase 2 diplexers and connect the amplifier between the VHF ports of each diplexer.
Then connect a short coaxial thru connection between the UHF ports of the diplexer.
This way you can leave the VHF amp on at all times when switching between VHF and UHF.
With the typical diplexer you will have about .25 db insertion loss on each diplexer so your amplifier output power (50dbm, 100 watts normally) to the antenna will be closer to 49.5 dbm or ~89.125 watts.
You will of course have a similar combined .5 db loss on the UHF side.
I use this method with a dual band 2meter/220MHZ HT and a 220 MHZ amp and 2 homemade diplexers feeding a 2/220 dual band mobile antenna.
TheSpaceMann
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Get yourself a small VHF beam instead! I have one made by ELK, and it can be used as a portable beam or mounted on a rooftop. It really increases your effective radiated power, and helps a great deal with receiving as well. For not much over $100 bucks, it is well worth the money!
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