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Author Topic: WHEN IN DOUBT USE A INTERFACE.  (Read 483 times)
N3JBH
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Posts: 2358




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« on: October 29, 2005, 10:56:15 AM »

I have seen this question asked sevral times will my rig work with this amp. and i know you folks are asking this in good faith. i dont mean to sound rude. but want a sure safe answer to your question. here it is when in doubt you a relay interface.

some times you may not need one sometimes you will. but heck for the cost of these gizmo's i say cheap insurance is a good thing here and here is some links to such interfaces folks. they will work with just about any radio& amp combo you can come up with in ham radio.

http://www.ameritron.com/products.php?catid=6
cost $50.00 aprox.

http://www.theheathkitshop.com/ampkeyer.html
cost $40.00 aprox

http://www.hamgadgets.com/product_info.php?cPath=21&products_id=75&osCsid=9621e68b2c89e6ac7c91a7a211e19bbd
cost around $15.00 aprox

so fella's here is the best way to be safe when in doubt. i never known any one to blow a radio or amp using one these items. and to be honest i think i use one even if i did not need it just for safty sake.

god bless.  jeff/n3jbh
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K0BG
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Posts: 9865


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« Reply #1 on: October 29, 2005, 11:17:57 AM »

This is just one of the questions that get continually asked. If folks would just do a search, they'd find the answer post haste.

I could name at least a dozen others. In fact, I've been thinking of canning some answers to make my life easier.

Alan, KØBG
www.k0bg.om
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KA5N
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Posts: 4380




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« Reply #2 on: October 29, 2005, 11:30:04 AM »

Alan "To struggle against adversity builds character" and some of us are becomming real characters!
Allen
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N0TONE
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Posts: 173




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« Reply #3 on: November 04, 2005, 03:26:08 PM »

Here's another one of many famous "really really really bad bits of advice".

It is NOT true that an interface "does no harm".

If you're using an old enough amplifier that it's got high voltage and/or current in the T/R line, then it's a given that the amplifier has a rather slow, clunky, old open-frame relay in it.

Such amps have such slow transmit-to-receive and vice-versua delay times, that you are guaranteed to hot switch.  In short, there will be a brief interval where your exciter is transmitting into an open circuit, and another brief interval where the amplifier is destined to be transmitting into an open circuit.  

You can avoid this by driving the amplifier with a same-generation old tube radio that also has a slow mechanical relay.  Or, if using modern solid-state gear, you have to correctly sequence things.

I have an outboard keying system whereby I FIRST key the amplifier, then the exciter, with a controllable delay time between them.  My key and/or mic plugs into the external keying system.

What's wrong with the outboard interfaces?  They all make the delay worse.

Sure, you can add an outboard interface.  That will prevent your exciter's relay from welding shut or burning open.  But eventually, the screwed up timing will cause your amplifier tubes to arc, and then you'll be receiving bad advice on using nichrome parasitic suppressors and other voodoo nonsense.

AM
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