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Hello--
Please note that I currently do NOT have a dog in any of the current digital dogfights
which are consuming quantities of various MOSFETs used as final amplifiers in
QRP equipment.
Has anyone considered experimenting with such vintage tubes as the 1T4, 3V4,
1U5, 1LN5, 1A5-GT ?. These are available in the $5.00-$10.00 NOS price range.
Objections in no particular order:
Filament power? 1.4 volts @ 50 mA -- 2.8V@ 100 mA (3V4)
Warm-up time? Consider running the filament at a fraction of full
power; switched by MOSFET
High voltage for the plate and screen?? Three 9-volt batteries connected in series = 27 V., falling to
18 volts at dropout.
Bulky, fragile tubes? Don't over-miniaturize the project, and don't use it as a football.
73--
Brad? AA1IP
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Nuvistors anyone?
73 John F5VLF
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On 13 Sep 2023, at 21:14, Brad Thompson <brad.thompsonaa1ip@...> wrote:
Hello--
Please note that I currently do NOT have a dog in any of the current digital dogfights
which are consuming quantities of various MOSFETs used as final amplifiers in
QRP equipment.
Has anyone considered experimenting with such vintage tubes as the 1T4, 3V4,
1U5, 1LN5, 1A5-GT ?. These are available in the $5.00-$10.00 NOS price range.
Objections in no particular order:
Filament power? 1.4 volts @ 50 mA -- 2.8V@ 100 mA (3V4)
Warm-up time? Consider running the filament at a fraction of full
power; switched by MOSFET
High voltage for the plate and screen? Three 9-volt batteries connected in series = 27 V., falling to
18 volts at dropout.
Bulky, fragile tubes? Don't over-miniaturize the project, and don't use it as a football.
73--
Brad AA1IP
|
Well, nuvistors would be an excellent idea, except for their relative scarcity nowadays.? Same with the 1V filament tubes. ?
How about a 6- or 12-volt filament miniature tube?? I won't suggest compactrons, which would be an excellent idea except?for their scarcity. ?
Weight will impose a penalty if you?need to string a bunch of 9 volt?batteries together and carry spares,especially for SOTA and hiking up 5,000 vertical?feet.
Still, there's nothing wrong with tubes for QRP.? After all, we did it for decades, back in the beginning.
73 Jim N6OTQ
Nuvistors anyone?
73 John F5VLF
> On 13 Sep 2023, at 21:14, Brad Thompson <brad.thompsonaa1ip@...> wrote:
>
> Hello--
>
> Please note that I currently do NOT have a dog in any of the current digital dogfights
> which are consuming quantities of various MOSFETs used as final amplifiers in
> QRP equipment.
>
> Has anyone considered experimenting with such vintage tubes as the 1T4, 3V4,
> 1U5, 1LN5, 1A5-GT ?. These are available in the $5.00-$10.00 NOS price range.
>
> Objections in no particular order:
> Filament power? 1.4 volts @ 50 mA -- 2.8V@ 100 mA (3V4)
> Warm-up time? Consider running the filament at a fraction of full
> power; switched by MOSFET
> High voltage for the plate and screen?? Three 9-volt batteries connected in series = 27 V., falling to
> 18 volts at dropout.
> Bulky, fragile tubes? Don't over-miniaturize the project, and don't use it as a football.
>
> 73--
>
> Brad? AA1IP
|
Nuvistors? ?I have a box of new never used Nuvistors. ?Around here someplace. Dave
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Show quoted text
On Sep 13, 2023, at 16:19, Jim Strohm <jim.strohm@...> wrote:
? Well, nuvistors would be an excellent idea, except for their relative scarcity nowadays.? Same with the 1V filament tubes. ?
How about a 6- or 12-volt filament miniature tube?? I won't suggest compactrons, which would be an excellent idea except?for their scarcity. ?
Weight will impose a penalty if you?need to string a bunch of 9 volt?batteries together and carry spares,especially for SOTA and hiking up 5,000 vertical?feet.
Still, there's nothing wrong with tubes for QRP.? After all, we did it for decades, back in the beginning.
73 Jim N6OTQ Nuvistors anyone?
73 John F5VLF
> On 13 Sep 2023, at 21:14, Brad Thompson <brad.thompsonaa1ip@...> wrote:
>
> Hello--
>
> Please note that I currently do NOT have a dog in any of the current digital dogfights
> which are consuming quantities of various MOSFETs used as final amplifiers in
> QRP equipment.
>
> Has anyone considered experimenting with such vintage tubes as the 1T4, 3V4,
> 1U5, 1LN5, 1A5-GT ?. These are available in the $5.00-$10.00 NOS price range.
>
> Objections in no particular order:
> Filament power? 1.4 volts @ 50 mA -- 2.8V@ 100 mA (3V4)
> Warm-up time? Consider running the filament at a fraction of full
> power; switched by MOSFET
> High voltage for the plate and screen?? Three 9-volt batteries connected in series = 27 V., falling to
> 18 volts at dropout.
> Bulky, fragile tubes? Don't over-miniaturize the project, and don't use it as a football.
>
> 73--
>
> Brad? AA1IP
|
OK, I've been tempted to mute every thread about those MOSFETs, because I'm not feeling they're as critical an issue as many others evidently do.? If the horse isn't dead from the beating it's taken, it must be hurting really bad by now. ;-)
However, THIS tube idea catches my interest!? Not because it's necessary, but because it sounds like a real steampunk project for the QMX!? Like a nixie tube clock or that wood/marbles clock just mentioned - a modern SDR/tube QRP rig would just be cool!
I admit I had to learn about Nuvistors... they seem like a good idea, especially if Dave was interested in finding new homes for the ones he has.? At least, at first glance.
73,
Brock VA7AV
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Nuvistors are interesting!? I had two of them in a 2 meter rx preamp back in the late 60's.? The tubes are still available, the sockets not so much.? Least expensive 5 pin socket I found just now was about $9 if you buy 10 of them ($90).? I can deal with a 6C4 much easier now.
73!? Mark K9TR
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The plate voltage would still need to be like 90V-200V. Don't let the allure of $5 tube fool you, unless you already have a fairly expensive high-voltage power supply lying around looking for use.?
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I originally got the idea from an SWL (later GM8BAR) with whom I went on DXxpedition as GC3PAI/A and ON5YB in the 1960s. He had built a receiver which could best be described as the transistor equivalent of the G2DAF.?
It performed very well but he was not entirely satisfied with the performance and was talking of replacing the front end with something based on Nuvistors, but ended up emigrating to Australia. He did not get as far as looking at low power PAs.
73 John F5VLF
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On 13 Sep 2023, at 22:33, ian007 via < ian007@...> wrote:
The plate voltage would still need to be like 90V-200V. Don't let the allure of $5 tube fool you, unless you already have a fairly expensive high-voltage power supply lying around looking for use.?
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There is at least one example of the 6N7 tube pressed into HF service, it's available in both glass and metal envelops.?
Justin N2TOH?
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Just ordered a few to try. With the 0-3.3 v drive from the IC should get 5W out on 630M. Will let you know in a few weeks. 6N7
N0UU
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Biggest issue with the tube mentioned is 2-3W is their max power at about 135V,
That would be for the 3A4 or 3A5
For higher power think 5763, 2E26, or 6146.
--
Allison
------------------
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direct email will go to a bit bucket.
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Nuvisters are for receiving use and max power would be in the 2-3W range for the tetrodes.
The triodes do less and must be neutralized or they will oscillate like most triodes
I happen to have worked with them and as tubes go they wer excellent to about 700-800mhz
but not so much for RF power.
Most of the tubes that would do any power over about 3W are costly for power consumed
(heater/Filament and plate).
FY look up the Hallicrafters HT37 phasing transmitter....? big and heavy and required much
tuning to keep them clean as the tubes drifted with age.? I know, I have one that I fire up?
from time to time.? There are others of the era.?
--
Allison
------------------
Post online only,?
direct email will go to a bit bucket.
|
Heathkit used the 6CL6 as a linear driver in the HW101 and
similar SB series line. Mike, KC0Y
On 9/16/23 11:21 AM, ajparent1/kb1gmx
wrote:
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Show quoted text
Nuvisters are for receiving use and max power would be in the 2-3W
range for the tetrodes.
The triodes do less and must be neutralized or they will oscillate
like most triodes
I happen to have worked with them and as tubes go they wer
excellent to about 700-800mhz
but not so much for RF power.
Most of the tubes that would do any power over about 3W are costly
for power consumed
(heater/Filament and plate).
FY look up the Hallicrafters HT37 phasing transmitter....? big and
heavy and required much
tuning to keep them clean as the tubes drifted with age.? I know,
I have one that I fire up?
from time to time.? There are others of the era.?
--
Allison
------------------
Post online only,?
direct email will go to a bit bucket.
|
Remember the 12BY7. ?
Heck, remember to look in an old-ish (early 1960s) ARRL Handbook and see what they show in the tube tables in the back.? There are plenty of options.?
A 12V filament is a good fit for most portable power sources ... same with two 6V filaments in series.? You still have the issue of the plate supply, but a chopper or switcher supply is simple enough.? Remember those tube-type CB mobile leen-yah amps with the two big round PNP transistors on the back?
You could even gut a 1940s VHF-lo-band mobile for its vibrator supply and 807s.? I have some of those, I think.
73 Jim N6OTQ
Heathkit used the 6CL6 as a linear driver in the HW101 and
similar SB series line. Mike, KC0Y
On 9/16/23 11:21 AM, ajparent1/kb1gmx
wrote:
Nuvisters are for receiving use and max power would be in the 2-3W
range for the tetrodes.
The triodes do less and must be neutralized or they will oscillate
like most triodes
I happen to have worked with them and as tubes go they wer
excellent to about 700-800mhz
but not so much for RF power.
Most of the tubes that would do any power over about 3W are costly
for power consumed
(heater/Filament and plate).
FY look up the Hallicrafters HT37 phasing transmitter....? big and
heavy and required much
tuning to keep them clean as the tubes drifted with age.? I know,
I have one that I fire up?
from time to time.? There are others of the era.?
--
Allison
|
The 2E26 Allison mentioned is perfect for portable rigs as they were designed for VHF mobile radios (think vibrations and the like). AF4K(SK) used one in a transmitter design that worked fairly well.....unfortunately, I don't have a schematic of Bry's rig. I think he used a 6C4 or similar for the oscillator.?
Lee KX4TT
On Saturday, September 16, 2023 at 12:36:23 PM EDT, Jim Strohm <jim.strohm@...> wrote:
Remember the 12BY7. ?
73 Jim N6OTQ
Heathkit used the 6CL6 as a linear driver in the HW101 and
similar SB series line. Mike, KC0Y
On 9/16/23 11:21 AM, ajparent1/kb1gmx
wrote:
Nuvisters are for receiving use and max power would be in the 2-3W
range for the tetrodes.
The triodes do less and must be neutralized or they will oscillate
like most triodes
I happen to have worked with them and as tubes go they wer
excellent to about 700-800mhz
but not so much for RF power.
Most of the tubes that would do any power over about 3W are costly
for power consumed
(heater/Filament and plate).
FY look up the Hallicrafters HT37 phasing transmitter....? big and
heavy and required much
tuning to keep them clean as the tubes drifted with age.? I know,
I have one that I fire up?
from time to time.? There are others of the era.?
--
Allison
|
Here I go, dating my age again. The acorn tube predated the nuvistor by a bit. It was a FB VHF/UHF amplifier or oscillator, and I made a very nice dip meter with one once, using a transmission line and slider for frequency control. Fun stuff! JZ On Sat, Sep 16, 2023 at 12:45?PM Lee via groups.io <kx4tt@...> wrote:
The 2E26 Allison mentioned is perfect for portable rigs as they were designed for VHF mobile radios (think vibrations and the like). AF4K(SK) used one in a transmitter design that worked fairly well.....unfortunately, I don't have a schematic of Bry's rig. I think he used a 6C4 or similar for the oscillator.
Lee KX4TT
On Saturday, September 16, 2023 at 12:36:23 PM EDT, Jim Strohm <jim.strohm@...> wrote:
Remember the 12BY7.
73
Jim N6OTQ
On Sat, Sep 16, 2023 at 11:26?AM Mike Downing KC0Y <michael.downing.kc0y@...> wrote:
Heathkit used the 6CL6 as a linear driver in the HW101 and similar SB series line. Mike, KC0Y
On 9/16/23 11:21 AM, ajparent1/kb1gmx wrote:
Nuvisters are for receiving use and max power would be in the 2-3W range for the tetrodes.
The triodes do less and must be neutralized or they will oscillate like most triodes
I happen to have worked with them and as tubes go they wer excellent to about 700-800mhz
but not so much for RF power.
Most of the tubes that would do any power over about 3W are costly for power consumed
(heater/Filament and plate).
FY look up the Hallicrafters HT37 phasing transmitter.... big and heavy and required much
tuning to keep them clean as the tubes drifted with age. I know, I have one that I fire up
from time to time. There are others of the era.
--
Allison
|
Here is my 220MHz Nuvistor converter for my NC-300 receiver back in the 60¡¯s (ARRL design). ?Also, the schematic is for my 10 meter mobile transmitter using a 2E26 with Heising modulation ¡ is was called the ¡°28-28¡± for 28 watts on 28 MHz. I used it with a HV Dynamotor in the car (see last picture) ¡ notice the relay contact to power it up on XMT. ?I also built a 2 Meter handi-talkie using Acorn tubes ¡ never got it to work.
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Here I go, dating my age again.
The acorn tube predated the nuvistor by a bit.
It was a FB VHF/UHF amplifier or oscillator, and I made a very nice
dip meter with one once, using a transmission line and slider for
frequency control. Fun stuff!
JZ
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Looks a lot like my Ameco 2M converter and my parks 432 converter both use nuvisters.
Both pretty decent.? The nuvistors wanted .135A per tube or .675 amps at 6.3V (4.2525W).
The dynamotor was aybe 65% efficient in providing the 90-120V needed.
I have a HE45A 6M am TRX,? uses 2E26 final.? Used Vibrator supply and all tube.? Sucks down
about 4.5a on receive run the heaters and upward of 6A on TX.? IT does about 12W.
Most were run off 120V AC.
Back in the dark ages (1970) I used to service radios like Motorola TU44UHF
For 4watts on UHF FM the standard power harness used 00guage wire direct to the
battery.? Running the RX alone could kill the average car battery is less than 2 hours
without the engine running.
Tubes are cool but for portable their power needs are painful.
Example A TBY-8 a 28 to 80mhz wwii? backpack portable using 7 tubea two for the audio,
one for crystal calibrator,?and Acorn tubes for superregen RX (two tubes) and two for TX.
33 pounds complete in the pack.? About 18 pounds of that was batteries.? The 0.5W TX had
a useful range of 10,000 yards.? ?I have one!, they were also known as codetalker radios.
I have a three tube (1R5, and two 1u4) 80m rx, it needs 1.4V at 150ma (tube heaters)
and 90V at 7ma for the whole plate load.? Ok for Am, forget SSB, too wide for CW.
Generally heating the tubes was hungry for power and the high volts were short lived.
The idea of a valve final for QRP assumes you car is the power source or
other large battery.? As heating the tube and providing the high volts will eat
many watts for maybe 15-25% efficiency (battery to RF).
Acorn tube were cool but Nuvisters were way better and smaller.
--
Allison
------------------
Post online only,?
direct email will go to a bit bucket.
|
This was the example I was unable to find the other night,?
?
Justin N2TOH?
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This reminds me of the ill fated AT2 two acorn 995 tube transmitted attempt from the 2020 FDIM build-a-thon and based on the Peter Parker PP2 that once appeared in SPRAT. 60 or so of us signed up and laid out $50 for a kit. FDIM was cancelled, but eventually we received bags of apparently miscellaneous parts. The kit included highly unusual hardware, but was never really documented. I never saw that Rex a completed kit as he sent out and as far as I know no one ever successfully completed theirs.
Occasionally I think about abandoning Rex's design and starting from scratch with the parts as a base, but other projects have been more interesting.
--
? 73
??? KD8CGH
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Mark K9TR
ian007
Lee
Bob Benedict, KD8CGH