collins 30L-1

kirk fitzner

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Mar 9, 2013, 6:17:42 PM3/9/13

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Hi all, i am looking for info on the collins 30L-1 power supply upgrade
kit.

--
kirk fitzner

Scott Dorsey

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Mar 10, 2013, 12:42:22 PM3/10/13

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kirk fitzner <kirk.fitzn...@radiobanter.com> wrote:
>
>Hi all, i am looking for info on the collins 30L-1 power supply upgrade
>kit.

Is there one? What is there to upgrade? The supplies in those things
is stiff and oversized, and everything is overrated.

There's stuff that you might want to replace as they get old, like those
electrolytics, but it's hard to imagine upgrading. Sometimes those
rectifiers fail, but hardly ever. It's a nice design.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Antonio I0JX

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Mar 14, 2013, 5:54:50 PM3/14/13

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"Scott Dorsey" ha scritto nel messaggio
news:khid5e$av4$1...@panix2.panix.com...

I remember having seen an "upgrade kit" on sale, in which the voltage
doubler was substituted by a voltage tripler. With 572Bs in place of 811s.
It would probably give a kW out instead of 650W, but the power transformer
would certainly suffer.

73

Tony I0JX
Rome, Italy

Scott Dorsey

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Mar 14, 2013, 6:59:24 PM3/14/13

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Antonio I0JX <vern...@tiscali.it> wrote:
>
>I remember having seen an "upgrade kit" on sale, in which the voltage
>doubler was substituted by a voltage tripler. With 572Bs in place of 811s.
>It would probably give a kW out instead of 650W, but the power transformer
>would certainly suffer.

That sounds horrible! The wonderful thing about those amps is that there
are enormous safety margins on everything and they are just solidly
over-engineered. Why would anyone want to wreck that for the sake of
less than one S-unit?

Antonio I0JX

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Mar 22, 2013, 3:47:47 PM3/22/13

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That sounds horrible! The wonderful thing about those amps is that there
are enormous safety margins on everything and they are just solidly
over-engineered. Why would anyone want to wreck that for the sake of
less than one S-unit?
--scott

Scott,

the Collins 30L-1 has safety margins on everything but the final tubes,
which can get easily damaged when the amplifier is tuned up by an
unexperienced operator. It is a common experience to open a 30L-1 and see
holes in the tubes plate. The 811s do not at all forgive operator mistakes.

Moreover, with only 260W available total dissipation, one must be very
careful also during normal operation, especially on CW. In my opinion using
the carbon-plate 572B in place of 811s is a must. Same output power, but
with 640W total dissipation.

Coming back to the "upgrade kits", I hate modifying any vintage equipment.
My philosophy is that, if I need something better or more powerful, I get
something else rather than modifying what I have.

Although I would never substitute the doubler with a tripler in my 30L-1
power supply, I must admit that it may not be a bad solution provided that:

- the 811s are replaced by 572Bs
- the amplifier is never pushed to a higher output power than before the
modification (that is about 650W), so that the power transformer and the RF
circuitry do not get stressed.

With the higher voltage produced by the tripler, a lower plate current would
result for a given output power, with advantages in terms of driving power
and linearity.

gunsr...@gmail.com

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Mar 22, 2013, 8:34:46 PM3/22/13

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I believe the upgrade you are talking about is the replacement of the Caps and Diodes on the multiplier board. Just replacing with better caps and diodes. With a little searching on that bay site, I'm sure you can find a source.
Tom

Michael Black

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Mar 22, 2013, 8:58:43 PM3/22/13

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That sounds familiar. For a long time, there were ads in QST, at least,
from some company selling "rectifier stacks" to replace vacuum tube
rectifiers. I guess they potted the diodes, they were a bit fancier than
just a board with semiconductor diodes.

Michael