Tokyo High Power HL 2.5 kW Linear
I had written a review of this amp earlier on the former W9OG forum site, however I had some of my readers ask to post it again.
I had become weary of the tube type amplifiers and the ever increasing costs of tubes to keep them going, so I made the decision a few months ago to purchase a solid state amp and see how they performed.
Granted, Ameritron makes a solid-state amp, but power supply problems seem to surface and the ratings on their offering have not been impressive. I opted to try the Tokyo High Power H L 2.5 unit and I am giving you my thoughts on the subject.
I found this unit from HRO as an open box unit, this does not mean anything was wrong with the amplifier, it does mean the box was opened and the unit taken out for a demonstration unit. Since it could not be sold for a new unit I had some cash knocked off the normal price and that was fine with me.
When the THP arrived there were no shipping problems or damage, it does arrive with out an A.C. plug, this is due to the many worldwide variations of A.C. receptacles.
However a quick trip to the hardware store and this problem was history, remember this amplifier requires a 220-volt A, C, line.
Once done with that the true test was a short time away, turning on the THP is accomplished with a power switch on the front panel, it is suggested that you place the operate standby switch in standby before switching on power.
Failing to do this will result in the amp going in standby, it must check itself prior to operation and this takes about two seconds. The status window indicates a go, or no go status upon power up mode.
Operation is a real breeze just select your band, bring up the drive power to indicate 1500 watts output and either start pounding the key, or open your mouth and talk. Be sure of course you have the T/R line plugged into the amp and your rig.
If you overdrive the amp, it will go to standby, if you draw too much drain current, it goes to standby and if your swr is too high, the amp goes to standby.
The status window indicates also the internal temperature of the amp, if it exceeds 90C the amp will go in standby. If you are drawing too much drain current a warning light flashes, if the condition continues the amp goes to standby mode.
The wattmeter indicates average output with about 50 watts of drive the average power indicates on the ssb mode about 700 to 800 watts. On cw mode you will see 1500 watts output and the THP can go to 1800 watts, but why? I do want to emphasize there are several ways to be a total idiot with this amp and running it at the maximum limit is one of them. You gain nothing and you may blow the finals and they are not cheap. Another suggestion is make sure your coax connectors are tight, do not attempt to use this amp with a make shift antenna.
Make sure you are on the right band before keying up and by all means make sure you have a resonant antenna for the band chosen.
There is an auto/manual switch on the front panel and with the proper cable for your rig you can plug in this cable to the THP and then to your rig. What this does is switch bands automatically from your transceiver. By all means only plug this in with the amp off, I prefer mine to be in manual since I do not have a multiband antenna, I opted for the mono band antenna.
Since you can monitor your drain current on the amp finals it is suggested that this be kept under 25A thirty is the maximum, so be sure and not overload the unit. There is no loading, or tuning controls it could not be simpler to operate and enjoy.
The cosmetics are first rate and the fit and finish is superb. The blower fan is quiet; the weight of the THP is 57 pounds, quite heavy for a package this small.
It is suggested that if you do not have a resonant antenna on the bands you wish to operate, or a segment of the band where your swr rises to more then 100 watts reflected that you use an antenna tuner. I for one am not using one since my beam is resonant over the entire twenty meter band with an swr of less then 1:5.
So far with about a year of using this amp no trouble of any kind has surfaced I have used this amp on 40 and twenty, the linearity on the scope is perfect. One more item for mention is the ALC line, follow the instructions in the manual for your brand of radio. Adjust the control on the rear of the THP for a slight decrease at 1500 watts. Watching audio peaks on my monitor scope indicates a nice non flat topped pattern.
Keep with in the manufacturers limits and you will enjoy many years of trouble free service. If you have questions about this amp, drop me a line and be glad to answer them for you.
