a few stupid questions about tube amps

[BOOTY MONSTER]

im just guessing but..........

is it safe to assume that cb tube amps have about the same quality compared to ham tube amps ..... as cb solid state amps do to say an icom or yaseu solid state amp ?

if im interested in a tube amp for am and ssb is a PTT switch my only or best option for am ?
are theyre any auto switching tube amps for different modes .

if it were tuned for channel 27.205MHz (into a dummy load for purely research purposes ) would any additional tuning be needed to cover the rest of the 11 meter/cb band ?

how do you folks feel the ameritron amps compare to other tube amps ? ive seen the reviews at eHam and they seem mostly positive .

seems tube availability is a worthy consideration . what are some of the tubes that are fairly inexpensive that would be safer to expect to be still be econonomically available in 10 or 20 years . i know no one is nastrodiumus , just a few guesses maybe .....

thanks

 

[bioman]

some of the older "CB" tube amps are decent.........D&A being (IMO) the best HOWEVER most of them ran "sweep" tubes which are expensive and scarce

the ameritrons are supposed to be VERY nice although i've never owned one

when i had power here i was running a yaesu 2100B which i was pleased with

yeah a PTT or a foot pedal would be your best bet unless you were running a real ham rig at which point you could probably buy or make a patch cable so the rig keys the amp

you COULD look at some amplifier schematics for 11M stuff and maybe build a "keyer" box that would run on RF..........i could probably do it copying D&As raider schematic (i know those amps inside out) but would need a 120 volt relay

your best bet for tubes would be to find an amp that tubes are still in production

i think the russkies are still making 811s along with several other transmitting type tubes

scott

 

[74IN]

is it safe to assume that cb tube amps have about the same quality compared to ham tube amps ..... as cb solid state amps do to say an icom or yaseu solid state amp ?

Nope.

CB SS amps are nowhere near the quality of an amateur SS amp.

The assembly might be, but not the finished product of the signal.

Also, ham amps are typically muti-banded.

Same goes for the tube amps.

Many CB amps are sweep tube amps, using old TV tubes.

If you just want to use it for CB, I can't see any reason not to use one, just replacements are scarce and expensive.

I've had some and liked them, but only as a base amp.

There is no comparison to an Ameritron, but for CB you don't need one.

 

[HiDef]

If a CB amp were built to the same standards as a hammy amp it would be marketed as a hammy amp. See Dentron GLA-1000.

Certain CB tOOb amps are built on the edge of destruction just like their transistor sisters. That Italian box with the EL-509/EL-519 tOObs is just waiting to melt when run at the power they advertise.

An example of a great tOOb hammy amp would be the Alpha 76 3 holer. TOObs are not easy to find but that amp will now fall apart like many others if used on AM.

Most hambone amps are good for CW and sillysideband only. Run them on AM to find the weak spots.

 

[SR385]

It all depends on the design....which likely means no.

As for tuning, again it depends on the design, but generally with my AL-80B I find it needs tuning about every 100kHz or so to keep it clean. Only takes a few seconds to do so it isn't like it is hard. Also if you tune up for full drive and operate at lower drive power after that, you can stretch it more without as much trouble. If you're hitting it hard, you have to keep it tuned up.

 

[BOOTY MONSTER]

ive read a few comments here and there about single tube amps being better just because theres only one tube to fail . but if a multi tube amp (like the ameritron 811/811H) is run at its rated power (600 & 800 watts) is its life expectancy about the same , all else being equal (i know rarely are all things equal) ? what would be a reasonable ammount of power to expect on AM with the 811 or 811H ? seems i recall someone telling me about half the power on am.......... ?

when i was a teen all the big stations in that lil town had either elkin or D&A amps . ive read that sweep tubes are dirty but a more than adaquate for cb given the nature of the other equipment designed for it . but IF i did manage to scrape up the bucks to move to a tube amp id want something that would be propper for the other bands . that way if i do decide to get a ticket id only have to buy a radio and hang some wire between trees and use the amp when needed .

the 80B seems to be a very nice amp . found this review of it about 2 years ago ....
W4TI - Review of Ameritron AL-80BQ Amplifier (with QSK-5PC Installed) Mr.Martin went silent key in oct 07 .
he has some good articles and the installation of the telephone pole for his hex-beam is very interesting IMO .

 

[RickC.]

Tube amatuer amps will operate well on AM, BUT-- keep the plate current less than half the full load value and keep the tubes cool. I use my old Heath SB 200 on 75m AM driving it with 25W carrier from an IC-718, gets 125W carrier out of the amp with no problems. You can get away with 100% duty cycle with SSB amps, but you have to cut the power back.

I think the GLA-1000 used sweep tubes, which never were very robust about handling heat. With RF tubes (811, 572, etc. ) you should be OK. The old Drake transmitters that used sweep tubes used a reduced carrier mode of AM in deference to those tubes-- completely different from plate modulated AM.


Rick

 

[W5LZ]

It's fairly simple with tube amplifiers, the tube specifications typically tell you what you can expect as output (same for transistors if you know how to read the specs). It also helps to know how a particular mode works and it's duty cycle. If you know those things then you can make a pretty good guess as to the typical output of an amplifier. Of course there are a lot of other factors that enter into it. How 'stout' of a power supply for those tube type amplifiers makes a very big difference. Not what kind, but how well the antenna connected to that amplifier is constructed and tuned makes a difference.
Sweep tubes, etc.
The problem with using sweep tubes is that they are not in general use in TVs anymore. That means that they are going to get scarcer from now on. Won't be a dime a dozen like they were at one time. The other problem with using sweep tubes is that they are all pushed past their normal operating limits and always have been. If you want them to last forever, you'd better be very conservative with them. CB'ers are not exactly known for being conservative, sorry 'bout that, but it's a fact. I think the reason for that is lack of knowledge and/or false information to start with. (Don't get the impression that hams are immune to that, they aren't, and for exactly the same reasons.)
And lastly, if you want a well designed/made amplifier, buy a commercially made and sold amplifier. Why? Cuz they got standards they have to meet. Those standards may be the minimum acceptable ones, but at least they have -some- standards. I think it would be smart to buy one that used an amplifying device (tube/transistor) that's going to be commonly available for a while.
From there I guess it's a matter of personal choice.
- 'Doc

 

[HiDef]

Well said Doc.

The only problem with sweep tubes is most circuits they find themselves in are asking too much. Sweep tubes are NOT dirtier than anything else. It's all in the design. I'd take a cathode driven 6LQ6 over a grid driven, without feedback 6146 any day.

Multiple tOObs used to be economical. Today, single tOOb designs are the easiest way to go. No matching tOOb B.S. and far less parts count. Easier troubleshooting too.

When evaluating amplifier capability, look at total device dissipation.

Take that number and multiply by 1.5 for slimeband P.E.P. OR A.M. P.E.P. output figure.

Take the dissipation figure and cut in half for maximum carrier on A.M. if you have excellent cooling and a monster plate supply.

Pair of 3-500Z is 1000 watts tOOb dissipation original specification. X 1.5 gives you 1500 watts P.E.P. output on SSB or A.M.

For A.M. carrier power you would get 500 watts from 2 3-500Z tOObs. This figure is with cooling better than any hambone commercial amp I've seen in 35 years of looking AND the power supply would need to be heavy duty.

A more reasonable number for an SB-220 etc would be 275-300 watts carrier with an extra fan.

A quad of 811As would be good for 125 watts carrier on a good day. Better of with 572B tOObs which have a much beefier plate structure.

The above figures will keep the operator out of trouble. Yes more power can be had at the expense of tOOb longevity.

 

[King Mudduck]

im just guessing but..........

is it safe to assume that cb tube amps have about the same quality compared to ham tube amps ..... as cb solid state amps do to say an icom or yaseu solid state amp ?

if im interested in a tube amp for am and ssb is a PTT switch my only or best option for am ?
are theyre any auto switching tube amps for different modes .

if it were tuned for channel 27.205MHz (into a dummy load for purely research purposes ) would any additional tuning be needed to cover the rest of the 11 meter/cb band ?

how do you folks feel the ameritron amps compare to other tube amps ? ive seen the reviews at eHam and they seem mostly positive .

seems tube availability is a worthy consideration . what are some of the tubes that are fairly inexpensive that would be safer to expect to be still be econonomically available in 10 or 20 years . i know no one is nastrodiumus , just a few guesses maybe .....

thanks

There is no comparing a "CB amp" to a true ham amp in build quality or performance! If you want an amp to bleed all over the band and enjoy waiting for everyone to go to bed before you use it then you can go with a D&A,Varmint or something along those lines. You know,a cheaply made amp that bleeds 40 above and below even with a clean radio. Or you could spend a little more money and get a Dentron,Pride,Heathkit,Collins, Ameritron or Henry and talk when ever you want with an amp that will last forever,if you use it with a little common since. And if your even thinking about using one on ssb you had better get an amp that is clean or the SSB guys will laugh you off of the channel!!

Power will be anywhere from 800 to 2000 watts depending on which amp you get....nice and clean to! Although if it were me i would stay with an amp that used the 3-500Z tube, lots of power and you should be able to find them for many years to come. The ceramic tube amps like the Pride DX-300 or a big Dentron work really to well but the tubes can be high as hell to replace!

You could have the PTT or foot switch with any of these amps i mentioned depending on how the were setup from the factory or you can change one to your liking as long as you or who ever knows what they are doing.

I have not heard anyone say a bad word about Ameritron and would feel safe about buying one.


And regardless of what you hear from others....you do not have to re tune the amp anytime you change the channel. I tune my on ch 20 and forget about it,difference in power across the band is less than 40 watts from ch 1 to 40.

I myself would rather have a nice clean tube amp than a doisy pleasing pill amp any day!