A Technical "Quandary" (For Nomad).

[paws264]

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I am sitting here on the horns of a dilemma, I am trying to figure out which way to go.

I have a tube amp on the bench for repair (type and output tubes unimportant) with a 6BQ5 tube keyer; the tube is shot according to my tester.

Now, here is the question, do I just run across town and buy a tube for $22.00 and slap it in there and get him out the door with a mark-up on the tube and a service charge

OR,

Do I convert the unit to a solid state (NPN) keyer and a low voltage relay (all available on hand) and get it out the door for the same price as with the new tube and service charge.

So, what do you think?

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[C2]

Or option 3, just pull that old dusty palomar off the shelf and swap the guts. You could probably sell the tubes on ebay. :twisted:

 

[bcrewcaptain]

I say pull it all out, it'll lighten the case and you can sell the parts on ebay

 

[paws264]

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I say pull it all out, it'll lighten the case and you can sell the parts on ebay

I think I smell something Coooo-Kiiiiiiing!

This is serious now, nobody wants a dead 6BQ5 and a relay with a high voltage coil (they would go into a bag to be returned to the customer) but since YOU bought it up, maybe if it was a TOP GUN MODULE, I could auction it off on eBay (NOW, are you satisfied? :roll: ) for bucks.

It's about time versus money, I await serious answers from qualified individuals; the peanut gallery can take it's remarks back to the "Solid-State P*ssing Match".

Thank you, thank you very much.

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[C2]

To me the question was a joke anyway.

Of course I would just change the tube. The only reason I would change the keying circuit is if the customer wanted it or the parts were no longer available or unreasonable to obtain. After that, it would still be the Customer's decision on how (or if) to repair the device. At least I would have to tell them of the options. I would not change the keying circuit without telling the customer first, regardless. Even if I had the tube in stock, I might offer the change as an option.

My customers are not mushrooms. I do not keep them in the dark and feed them a load of cr@p.

 

[paws264]

To me the question was a joke anyway.

You know, you may just be correct, it might just be a joke, but then again you might not be correct......

Of course I would just change the tube. The only reason I would change the keying circuit is if the customer wanted it or the parts were no longer available or unreasonable to obtain. After that, it would still be the Customer's decision on how (or if) to repair the device. At least I would have to tell them of the options. I would not change the keying circuit without telling the customer first, regardless. Even if I had the tube in stock, I might offer the change as an option.

My customers are not mushrooms. I do not keep them in the dark and feed them a load of cr@p.

All very good points, but what if the bottom line is cost, either way he (the customer) goes, he's gonna pay the same amount and he says, "Do what's best", so do you maximize your profit or do you maximize your time?

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[AMPOWER]

well its the same cost either way yes?? (for the owner)
I would have to say which ever way is going to be better
for the amp its self...id say do that...

Your customer will be happier in the long run with his amp...
and the customer is happy..
that is ALL THAT MATTERS...

AM POWER

 

[paws264]

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Well, that's why I'm waiting to see what Chris has to say.

I am not going to say that it is unusual for the tubes in the hi-voltage keyer to fail but I have not seen one, I am just interested in his ideas of "Failure Modes" for the tube circuit.

Tubes are more forgiving and easier to replace when it comes to circuit problems but transistors are 1000 times cheaper ($22.00 vs .22 cent). And, if for some reason I did not get it right the first time instead of having to replace a 22 buck tube, I just solder in a 22 cent transistor.

There is more initial work to change from tube to solid state but long term, changing to transistor keying might be the answer to the question.

But, take into consideration what C2 said........

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[Moleculo]

I'm not Nomad but....

...I would present the question to the customer (unless he already provided instructions). I may not understand his motivation for wanting the amp repaired....is he a collector or a purist with his equipment and wants everything stock for collectibility sake? Or is he on a shoe-string budget and just wants something reliable that won't fail or cost him extra $$$ to run it?

I would explain the options to him, the pros & cons and see what his response was. Depending on his answer, I would make the decision.

 

[nomadradio]

Boy, I arrived at this one a little late.

Hey Mole, you got it pegged.

I try to offer a customer a choice. When each side of the question will cost exactly the same, I'll trust my own judgement as to which choice is the better money's worth.

And when there IS a price difference, the 'better', or more reliable and trouble-free choice ALWAYS costs more. If the better choice were cheaper, there wouldn't be any decision to make, right?

That is where my favorite "Are you gonna keep it or sell it?" question becomes valuable. If he's gonna keep it, spending a few more bucks to save him a trip back to the shop will pay off.

If the owner is just going to unload the thing, keeping the price down is nearly always his first choice.

And as far as the technical judgement, a new relay is nearly always a better bet than an old one. Moving parts always go bad if you use them long enough. An old relay will nearly always cause trouble sooner than a new one.

There's another risk I'll remind the customer about when this question comes up: reliability. A keying tube may fail and key the thing while you're looking the other way. If you're in the room, and hear your channel chatter disappear, you'll shut it off before it can burn up.

Walk away from the radio room for too long, and the first hint may be the smell of smoke, or a child running into the room, shouting "Daddy, there's FLAMES shooting out of your radio! "

I am NOT a fan of tube-type keying circuits. I use a TO-220 power transistor, just because it's so hard to blow out. Costs the customer two bucks instead of the one buck he'd pay for a PN2222 or PN2907A. More important, it will be a lot more sensitive at low carrier power. SSB delay is a lot smoother and more stable, besides. But the final decision about how much to spend and why is still the customer's call.

And sometimes a customer takes the cheap choice, and cusses me when it breaks in two months. Just like I told him it would.

73