Guess I should have been more specific. USA sources would be preferred. Also
heard from OM Technology that they would not sell tubes to folks who do not
have their amplifier. I was also trying to confirm that the Chinese had
started new production of the GU84B but I cannot find that info either.
Tom Taormina, K5RC
Comstock Memorial Station, W7RN
Storey County ARES, KS7AA
www.w7rn.com
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of
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Sent: Friday, January 30, 2015 9:00 AM
To: amps@contesting.com
Subject: Amps Digest, Vol 145, Issue 58
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When replying, please edit your Subject line so it is more specific than
"Re: Contents of Amps digest..."
Today's Topics:
1. Re: GU84b tubes (Jim W7RY)
2. Re: GU84b tubes (Joe Subich, W4TV)
3. Re: GU84b tubes (Steve Bookout)
4. Re: GU84b tubes (Alek Petkovic)
5. Re: What tube? (Roger (K8RI))
6. Re: What tube? (Manfred Mornhinweg)
----------------------------------------------------------------------
Message: 1
Date: Thu, 29 Jan 2015 18:12:37 -0800
From: "Jim W7RY" <w7ry@centurytel.net>
To: "Behiels jean-Pierre" <on4aef@telenet.be>, <amps@contesting.com>
Subject: Re: [Amps] GU84b tubes
Message-ID: <8A7FE151882B4FA2888A5454AD8FEB95@JimsLaptop>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
Bad link.
Jim W7RY
-----Original Message-----
From: Behiels jean-Pierre
Sent: Thursday, January 29, 2015 7:33 AM
To: amps@contesting.com
Subject: [Amps] GU84b tubes
Subject: GU84b tubes
They are for sale at : www.ur4ll.com for 390 US$
Regards Jean .
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------------------------------
Message: 2
Date: Thu, 29 Jan 2015 21:46:03 -0500
From: "Joe Subich, W4TV" <lists@subich.com>
To: amps@contesting.com
Subject: Re: [Amps] GU84b tubes
Message-ID: <54CAF06B.3010001@subich.com>
Content-Type: text/plain; charset=utf-8; format=flowed
30 seconds with Google gives www.urrll.net
73,
... Joe, W4TV
On 2015-01-29 9:12 PM, Jim W7RY wrote:
> Bad link.
> Jim W7RY
>
>
> -----Original Message----- From: Behiels jean-Pierre Sent: Thursday,
> January 29, 2015 7:33 AM To: amps@contesting.com Subject: [Amps] GU84b
> tubes
>
>
> Subject: GU84b tubes
>
>
> They are for sale at : www.ur4ll.com for 390 US$
>
>
> Regards Jean .
>
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
------------------------------
Message: 3
Date: Fri, 30 Jan 2015 02:50:04 +0000
From: Steve Bookout <steve@nr4m.com>
To: amps@contesting.com
Subject: Re: [Amps] GU84b tubes
Message-ID: <54CAF15C.3020001@nr4m.com>
Content-Type: text/plain; charset=windows-1252; format=flowed
What do you get if you spend 31 secs? www.ur4ll.net?
73 de Steve, NR4M
On 1/30/2015 02:46 , Joe Subich, W4TV wrote:
>
> 30 seconds with Google gives www.urrll.net
>
> 73,
>
> ... Joe, W4TV
>
>
> On 2015-01-29 9:12 PM, Jim W7RY wrote:
>> Bad link.
>> Jim W7RY
>>
>>
>> -----Original Message----- From: Behiels jean-Pierre Sent: Thursday,
>> January 29, 2015 7:33 AM To: amps@contesting.com Subject: [Amps]
>> GU84b tubes
>>
>>
>> Subject: GU84b tubes
>>
>>
>> They are for sale at : www.ur4ll.com for 390 US$
>>
>>
>> Regards Jean .
>>
>>
>> _______________________________________________
>> Amps mailing list
>> Amps@contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>> _______________________________________________
>> Amps mailing list
>> Amps@contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
------------------------------
Message: 4
Date: Fri, 30 Jan 2015 11:46:37 +0800
From: Alek Petkovic <vk6apk@bigpond.com>
To: Amplifier Mailing List <amps@contesting.com>
Subject: Re: [Amps] GU84b tubes
Message-ID: <54CAFE9D.80902@bigpond.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Yep.
Dr Alex is a great guy to buy from as well. Prices and service are the best.
73, Alek
VK6APK
On 30/01/2015 10:50 AM, Steve Bookout wrote:
> What do you get if you spend 31 secs? www.ur4ll.net?
>
> 73 de Steve, NR4M
> On 1/30/2015 02:46 , Joe Subich, W4TV wrote:
>>
>> 30 seconds with Google gives www.urrll.net
>>
>> 73,
>>
>> ... Joe, W4TV
>>
>>
>> On 2015-01-29 9:12 PM, Jim W7RY wrote:
>>> Bad link.
>>> Jim W7RY
>>>
>>>
>>> -----Original Message----- From: Behiels jean-Pierre Sent: Thursday,
>>> January 29, 2015 7:33 AM To: amps@contesting.com Subject: [Amps]
>>> GU84b tubes
>>>
>>>
>>> Subject: GU84b tubes
>>>
>>>
>>> They are for sale at : www.ur4ll.com for 390 US$
>>>
>>>
>>> Regards Jean .
>>>
>>>
>>> _______________________________________________
>>> Amps mailing list
>>> Amps@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/amps
>>> _______________________________________________
>>> Amps mailing list
>>> Amps@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/amps
>>>
>> _______________________________________________
>> Amps mailing list
>> Amps@contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>>
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
--
From sunny Binningup, Western Australia.
------------------------------
Message: 5
Date: Thu, 29 Jan 2015 23:37:45 -0500
From: "Roger (K8RI)" <k8ri@rogerhalstead.com>
To: amps@contesting.com
Subject: Re: [Amps] What tube?
Message-ID: <54CB0A99.4020202@rogerhalstead.com>
Content-Type: text/plain; charset=utf-8; format=flowed
On 1/29/2015 5:19 PM, Gerald Williamson via Amps wrote:
Not necessarily. Particularly older glass bottles like the 813 and
glass to metal like the PL172 which go gassy with little or no use.
Good 813s are gettiong harder to find and I think PL172s are rare while
the 8295A version brings a premium price.
73
Ro0ger (K8RI)
> Bill, he had the right idea; except they last longer if you never turn
them
> on!
>
> 73,
> Gerald K5GW
>
>
>
>
>
> In a message dated 1/29/2015 2:08:25 P.M. Pacific Standard Time,
> wlfuqu00@uky.edu writes:
>
> We had a guy in our club that believed that tubes would last longer if you
> never turned them off.
> Naturally, the tubes were completely flat after he had not used the
> amplifier over a period of time.
> Practically no emission, but they did glow.
> bill =
> _______________________________________________
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> http://lists.contesting.com/mailman/listinfo/amps
>
>
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------------------------------
Message: 6
Date: Fri, 30 Jan 2015 16:19:26 +0000
From: Manfred Mornhinweg <manfred@ludens.cl>
To: amps@contesting.com
Subject: Re: [Amps] What tube?
Message-ID: <54CBAF0E.2090100@ludens.cl>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> you can be sure that tube life is adversely affected by frequent
> on/off cycles of the filament.
Well, then it seems to be a bad idea to do so. Which puts tubes some more
points
behind solid state devices for me, because in my particular case the power
consumption during RX is an important matter, as I typically listen a lot
more
time than I transmit, but want to have the amp ready to use at any time, and
in
summer I'm very short on energy, given that my electricity comes from a
small
turbine in creek that every summer seems to have less water than the summer
before. At this time (southern summer, and it hasn't rained even one drop
for a
full month), I'm barely generating 450W, and have to run the whole home on
that.
I use a battery buffering system, that allows me to draw 3kW for peaks
during
SSB transmission, but spending 200W all the time during RX for keeping
filaments
hot is a problem.
In winter instead power is no problem here, and it's free.
So I will have to keep looking into solid state amps, or just operate with
100W
only during summers.
> One of the current tube manufacturers (Burle
> I think) has a paper on his website that suggests that one on/off cycle
of
> the filament power is roughly equivalent to reducing tube life by 60
hours.
> If you expect say 18000 hours, the 300 on/off cycles pretty well uses
that
> up.
That seems overly pessimistic to me. I must have switched my NCL-2000 on and
off
many more than 300 times, and the tubes are still good. But it's very
reasonable
that filaments should suffer some wear from power cycling.
> This was for a larger transmitting tube so perhaps the 60 hour figure is
> not accurate for a 3-500Z or similar but the principle applies.
I think so. Also a lot must depend on the amount of inrush current.
My idea about an amp that powers down the filaments during RX was based on
using
a switching power supply. This has at least 3 advantages: Lighter, cheaper,
and
provides a regulated voltage. But in the case of filaments, there is an
additional advantage: Current limiting. If I build such an amplifier, I can
precisely set the filament current limit. The filament would come up at that
current, which could be as low as 120% of the nominal current, until getting
into voltage regulation when it's hot.
But that will obviously slow down the heating! The amp's power supply would
need
to power up the high voltage section once the filament current has become
the
nominal one, meaning that the filament is up at operating temperature. Two
question arise here: How long would it take to bring the filament up to full
emission, at a current limit of 120, 150 or 200%? And would such a
controlled,
slow heating avoid all or most of the power cycling damage? I fear it
wouldn't,
because the heating and cooling filament will still expand and contract,
causing
some friction in its supports, which might abrade it over time. But maybe
the
life span would be long enough to be acceptable, and maybe the startup
process
would even be fast enough to be acceptable. But I tend to doubt it.
Lacking data on it, probably only an experiment would show.
Gerald,
> he had the right idea; except they last longer if you never turn them on!
Well, that's pretty much what I do to make mine last! ;-)
Carl,
> If you use care in selecting the filament transformer it can be self
current
> limiting.
Yes, but in 2015 it's simpler and much cheaper to use a switching power
supply.
You don't even need to build it! You can buy ready made switching supplies
in
many voltage and current ratings. Many of them have adjustable voltage, and
adjustable current limiting. Power supplies to feed 5V 15A filaments, or
12.6V
10A filaments, cost like 20-30 dollars, new. Much cheaper than a decent
filament
transformer. Much lighter too. And you get a precisely regulated voltage,
with
wide tolerance to line voltage variations, plus adjustable current limiting!
It's really the way to go. I wouldn't put a big chunk of iron and expensive
copper in any new amplifier.
If you are willing to make some simple modifications, you can use old PC
power
supplies to power either type of filament. Such power supplies are typically
available for free. I have a bunch of them here, obtained from old junked
PCs.
The high voltage supply instead is not as easily or cheaply available in
switching technology, so that's a thing one should build oneself. It's not
hard,
though. The usual approach is to rectify and filter the line voltage into
roughly 320VDC, apply that to an IGBT bridge, that is controlled by a PWM
chip
and powers several compact ferrite transformers in parallel. The secondary
of
each transformer is full-wave rectified with ultrafast diodes, filtered by a
simple LC circuit, and the DC outputs from each section are all placed in
series. Add some RFI suppression, and that's it. It's more complex than a
conventional supply, but _much_ less expensive, hugely lighter,
short-circuit-proof, and delivers a regulated HV, tolerating a wide range of
line voltages. And if desired, it's rather easy to add power factor
correction.
That's useful if you want to run a big amp from any normal power outlet, or
from
a tightly sized generator.
> The 4-400 and GU-81M can both be run in GG. In a SB-220 with100W of drive
> you can expect 1000W due to a bit lower gain than the 3-500Z.
Good to know. But somehow I don't feel comfortable doing that! I mean, a
tetrode
or pentode was designed as such, and not intended for GG with all grids tied
together! Given that a 3-500Z is slightly less expensive than a 4-400 of the
same quality, I would certainly use the 3-500Z if I built a GG amplifier and
had
to choose between those two only.
And the GU-81M seems to work at very high grid and screen voltages, compared
to
other tubes. I wonder how it behaves in GG. I can imagine it being very hard
to
drive in that configuration.
> Crank up the voltage at the same 100W and 1500W is likely attainable even
on
> 10M with full emission tubes,
That also forces an increase in the Q of the tank circuit, requiring very
good
components - typically vacuum caps, big silver plated coils and the like.
Perfectly doable, but not really optimal.
> those are often $20-30 NIB military surplus
> into the 70's. Sockets are the same as the 3-500 and the flat glazed
ceramic
> Johnson style are $15-30 at US hamfests and Fleabay. The Eimac SK-410 runs
> about twice that from the same sources.
OK.
> Im using GU-81M's as AM modulators and the sockets are often more
expensive
> than the tubes from most European sources.
That's what I saw too. And a good socket for those tubes isn't very easy to
home
brew. Anyway, we are talking far less money for a GU-81M plus socket, than
for a
3-500Z alone!
> A tube that Im surprised you and others overlooked is the QB5/1750,
popular
> in BCB and SW broadcasting.
Probably because it doesn't show up in ham literature! I had never heard of
it.
Well, interesting musings. Now if there only was enough interesting activity
on
the bands, to justify building a new amp! It's ages, really, since I last
found
another ham on any band with whom it was possible to discuss technical
things.
Most seem to know at most something about the current weather in their area,
and
can rattle down the model numbers of the radios and antennas they use. And
that's for local contacts. If it's DX, it's almost invariably "hello - five
nine
- thanks for the contact - next station please!"
Oh well...
Manfred
========================
Visit my hobby homepage!
http://ludens.cl
========================
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