VHF Amps Part 2.
So you must have an amplifier for VHF so now what do we do first? Well first of all we decide what model we want and we either make the phone call, order it on line or pick it up at our local ham store.
Normally, ordering on line expect about a two week processing and shipping time, so once that box arrives let’s see what we need to do.
If you ordered the 160 to 200 watt unit with the newer TE units they have Anderson power pole connectors installed in the rear of the unit. You just need to make your cable to fit them. In some units they use a Cinch Jones plug and I actually prefer this it is a four pin plug using two terminals for negative and two for positive. The reason this is done is to provide maximum current conductivity from your power supply via your power cable.
If you have the Anderson cables, be sure you use at least 30 amp connectors since the amp will draw 24 amps at full power capacity. Now this brings me to the power supply, your 20-amp supply you are using for your rig, HF, VHF will not cut the current demand for your new amp. If you plan on running your two-meter rig and amp off the same supply, then I would recommend a 40 to 50-amp supply.
Before anyone asks why so much the amp at full power draws 24 amps and the rig, although you may be using it to drive the amp using 25 watts will draw about 8 amps. So now add those two and you come up with 32 amperes. A 40-amp supply will give you a slight margin, but a 50 might be the one you decide to purchase, that of course is your decision.
On the 400 watt amp from TE you have two stud connectors in the rear of the unit, for my six meter amp I believe they are 8/32 at least, or 10/32 not sure of the size but rather large to handle the current demand. For this brute T.E. recommends a #6 wire I have #8 and found it has handled all the current demand and at 54 amperes my 70 amp power supply handles this with ease. I had asked for the #6 wire, but the electrical store would only sell me that in 100-foot rolls, I did not need 100 feet of course. They did have a short run of #8, so this has worked fine for me over the years.
If you plan on using the 200-watt unit then the wire for the cable can be 10, or 12 gauge depending upon the specs the manufacturer suggests. Be sure and use the right Anderson connectors and the right choice if you use a distribution box
If you have stud connectors on your amp, I preferred to use ring lugs, insert the wire into the lug compress it tight enough to hold the wire solder the lug fit it over the stud, use the washers provided, tighten the nuts securely. This way it insures a good connection, do the same on your power supply tighten the nuts tightly, but you do not have to over torque. If you use a rig blaster box for power, I would suggest you wire your amp around this and go to the power supply terminals. The power supply and the amp have internal fuses so you are protected, the rig blaster may not provide enough current demand for the terminals you plan to use. I have done this with my six-meter amp and it has worked fine over the years. Do expect the amps to dissipate some heat, they have a thermal protect in the TE units and I have run mine to the point of shut down, it goes to standby until it cools off. I work mostly cw on six meters and drop the power to about 300 watts. This gives me plenty of power to work out on six meters. On SSB I run the drive up to get the full 400 watts output, but after prolonged use sometimes the amp shuts off, or goes into standby because of the heat buildup.
One item I should mention is make sure that your antenna will handle the higher power, some are rated at 250 watts, others at 500 and some at 1500 watts. Check your antenna system for a good SWR before you hit that PTT button.
If you are planning to run on FM with your new amp you will not have to worry about a keying line, most amps of this variety have carrier trip or excitation. So, with FM you have a carrier, if you push the PTT button your rig is transmitting a carrier, thus even if you do not say a thing the radio is transmitting a carrier and is amplified by the new amp as well.
Enter SSB, you have no carrier and the RF output is governed by the amount you modulate, or the audio gain on your transceiver. You will need to rig a key line; it is nothing more then completing a circuit to ground. So, you need a relay terminal in your rig that will provide this, it can be found usually on the rear of the transceiver. Consult your manual where it is and how to access it, via 8-pin plug, RCA cable etc. You will have another connection on the amp, sometimes it is a phono jack or modular jack, consult the manual for the location and pin out.
Without the keying line on ssb your TR relay in the amp will chatter since it is seeing a varying level of RF. It can also due to its slowness to respond blow the FET in the preamp if you have a model with a preamp! If you plan on running two-meter ssb, or 70 cm ssb or six-meter ssb a keying line is a must.
Once wired the relay in your amp keys with the transceiver and drops out per the adjustment of the vox delay. If you key the rig, do not say anything, the rig is on in transmit, the amp is on in transmit, but no output is happening until you speak.
If you release the PTT button, the rig and amp drop off at once, or if you use Vox and speak it will drop off per the vox delay setting.
So now, all you need is a short input cable, from your transceiver to the input of the amp and connect the antenna to the output of the amp. You are now in business with a stronger signal on 2, or 6 or 70CM what ever you choose.
Good luck and hope your signal picks up a few s units in the process.
