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6m Larcan Conversion

I plan to replace the input connector with a BNC. I want something that locks in place avoiding the issue of accidently having it come off in mid QSO. IMHO it is easier to replace the input connector than install a connector on the small cable. At least with my fingers and eyes.eyesight
 
I read somewhere about the amplifiers being used around 40MHz, possibly in Australia. It would be quite interesting to see what changes were performed to get it that low.

Be very careful with attempting any changes. Without proper sweep equipment you have no real way to determine what's happening and are essentially working blind. Sometimes it's best to leave things as they are.
 
i do intend to leave it as is, having said that i always like to see what everyone is doing, from extreme to mild its good to gather all opinions you can.
 
I finally got around to testing the power supply I picked up on Ebay. It is a good news/ bad news situation.

Bad news: It powers up but has no output despite having shorted the logic pins that allow it to power up when not installed in a server which is what it was intended for.:cursing:

Good news: I shorted the wrong pins.:headbang

Bad news: Apparently I am due for a new eyeglass prescription. There goes enough for two more of these amps. :cursing:

Good news: I found my magnifying glass and jewelers loupe. It works now. :thumbup:

51 volts out and 57 amps available. It should work rather well with a couple feet of 8 ga. wire I have some flexible 4 ga. but I don't think it is necessary for such a short run.

Next step is to replace the I/O connectors and work on the cooling. I found a pair of long cage blowers that require 100 volts each ???. I have no idea where I ever got them from. The pair of them in series on 120 volts runs almost silently yet push a fair amount of air. The two of of them are the same length as the entire heatsink so they will allow the entire unit to have air flow.
 
How does the supply work at low current draw? The specs say it requires a 10% minimum load or roughly 5.7A. Is the idle current of the amp enough for the power supply to work properly?

Do you have a means to monitor output voltage as the load changes rapidly? I used a 80A 28V switch mode supply on a TV transmitter, but it didn't work well. During sync pulse and max current the output voltage would sag, essentially rendering it unusable. For voice service this may not be as much of a problem, but could be interesting to see what happens.
 
Not sure Warren. I didn't have time to run any real tests other than does it have output or not. I am off to work tonight and tomorrow night and then off for four days so I hope to do some more performance tests then. I suspect the normal bias current should be enough to handle the requirements during actual keydown when the bias is turned on. IIRC the total bias current is about 5 or 6 amps so that should be fine. As for metering I am not sure.A voltmeter is the easy part. I have a meter shunt that provides 1 mV per amp and is good for up to 150 amps. That along with a suitable meter and a new meter scale should be fine. I asked the electricians at work what they had for current meters but the only ones they had were 1200 amps full scale. Not sure what the actual meter sensitivity was without the shunt. One may make a good 120 amp meter.
 
Warren, probably will go with a BNC on the input. I found a nice right angle N off of a junked antenna that will flush mount in place of the circuit board mounted quick connect output connector that is on there. Which, by the way my boss recognized as one used on some military radio equipment.

Another concern I have is RF noise generated by the power supply. I talked to another ham here in Florida that ended up with an expensive Mean Well power supply to power his amp.

I guess I will not know how mine will behave until I power it up.
 
Update:

I have so far ordered

a bird dual line section

low pass filter

sequencer

realys.

now i need:

power supply, 2 bird meters, current and voltage meters.
 
What did you order for a low pass filter? You do not see too many LPF's with a cutoff freq. above 6m. I have been contemplating an LPF but have also been considering using tuned stubs as well as 99% of my operation on 6m is confined to 50.125 to 50.200 MHz.
 
i got a old school drake the guy array solutions recommended, he kept telling me not to fool with stubs, as he felt they were too broad banded, and that nothing he ever made could take the power and he stopped making them a long time ago, he swore to me get the old drake tv 1000 in the COPPER case, although they say on 6m it cant take the power, i fugred for the price id buy it and decide later.
 
The Drake TV-1000 is rated for 1000 watts on HF and only 200 watts on 6m. With stubs the bandwidth and depth of notch is dependent on the quality of transmission line used. Cheap RG-8 is barely acceptable while heliax is great.
 

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