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Author Topic: Tube vs. SS / Amplifier IMD Tests / Tirode vs. Tetrode vs. Solid-State  (Read 48571 times)
NN2X
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Posts: 369




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« Reply #45 on: February 10, 2018, 07:19:24 PM »

Although the focus are on various specification (IMD and so on), the power out was missed..

For most Ham operators, pulling funds from the family budget it a difficult one..!

Heath Kit SB220,..Almost 1500 Watts, and costs down to 500 - 800 (USD)...The solid state amplifier for 1500 watts, is very expensive.(No matter used or new..

Watts, are Watts, no matter how they are generated..

My point being, I hope someday the SS Amps are similar to the price break points when compared to Tube amps

I owned QRO 2500DX, SB 220, Kenwood 922 and Emtron DX3 SP...All of these costs no more than 1 dollar per watt..
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KA4WJA
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Posts: 1098




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« Reply #46 on: February 10, 2018, 08:22:22 PM »

Tom,
1)  Yep, the gist of this thread is about spectral purity / IMD, and I don't want to drift too fat off the topic...but, yes, cost IS a factor!

Although the focus are on various specification (IMD and so on), the power out was missed..

For most Ham operators, pulling funds from the family budget it a difficult one..!

Heath Kit SB220,..Almost 1500 Watts, and costs down to 500 - 800 (USD)...The solid state amplifier for 1500 watts, is very expensive.(No matter used or new..

2)  I built my SB-221 over 35 years ago....got it brand new on closeout, think it was $379!!
Today (and for the past 10+ years) my best friend and his XYL use it every day!! 
Original Eimac 3-500z's (38 - 39 years old), still full-output!

But, unless you've improved the PS (bigger xfrm, etc.) you'll not get 1500 watts out of it...
Think I got 1300 or so, on 75m....

And, on the used market, a clean SB-220 / SB-221 with good tubes, sells for about $600 - $750...which is about the best bang-for-the-buck in HF amps....AND..
And, a pretty decent amp too...
Quote
Heathkit SB-221 (2x 3-500z's)   =  35/48/61/63



3)  But, I disagree with you here...
Watts, are Watts, no matter how they are generated..
The opposite is what this thread is all about!  Smiley
A clean signal is important.
Please have a look here:
https://www.eham.net/ehamforum/smf/index.php/topic,97093.0.html
https://www.eham.net/ehamforum/smf/index.php/topic,97093.msg1053647.html#msg1053647



Thanks for adding the thoughts about cost!

73,
John,  KA4WJA

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AF6LJ
Member

Posts: 4




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« Reply #47 on: February 10, 2018, 08:47:04 PM »

You can't really compare tuve VS solid state amps like that.
Tube amps have no protection circuits, they need to be manually tuned, and are very simple devices, with a low parts count.

A solid state amp doesn't require tuning. (or has an automatic antenna tune function) is full of protection and monitoring circuits, not to mention the parts count is quite a bit higher than the tube amp of the same power level.

When you compare a BLF188 to the cost of a 3-500Z they are about the same, the cost is in the support circuits needed to protect that BLF188, in spite of the claim it is capable of withstanding an infinite VSWR. Yah you can short them, and run them into an open circuit, you cannot run them into a high VSWR at all phase angles without derating them considerably. (It says so in the data sheet.)

I picked a fet for this because bipolar transistors are almost as outdated as the tubes in that SB-220/221, etc...

In terms of IMD the modern FETs are comparable and in many instances better than vacuum tubes in terms of IP3.
You just can't beat the crap out of them like you can a vacuum tube.


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KA4WJA
Member

Posts: 1098




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« Reply #48 on: February 10, 2018, 08:55:45 PM »

Sue,
We are all entitled to our own opinions and personal tastes...so no worries...Smiley


But, I completely disagree with you here.
In terms of IMD the modern FETs are comparable and in many instances better than vacuum tubes in terms of IP3.
You just can't beat the crap out of them like you can a vacuum tube.
Would you mind showing me these FET amps?  
And, their actual IMD tests?
Thanks.
Be sure to have a look here:
https://www.eham.net/ehamforum/smf/index.php/topic,100600.msg809648.html#msg809648
https://www.eham.net/ehamforum/smf/index.php/topic,100600.0.html



Oh, and for a rather lengthy discussion of IMD of transceivers / exciters, be sure to have a look:
https://www.eham.net/ehamforum/smf/index.php/topic,97093.0.html
https://www.eham.net/ehamforum/smf/index.php/topic,97093.msg1053647.html#msg1053647



73,
John,  KA4WJA


« Last Edit: February 10, 2018, 09:01:28 PM by KA4WJA » Logged
AA2UK
Member

Posts: 928




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« Reply #49 on: February 10, 2018, 09:18:44 PM »

http://www.w6pql.com/1_kw_sspa_for_1_8-54_mhz.htm
Bill, AA2UK
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KM1H
Member

Posts: 5573




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« Reply #50 on: February 11, 2018, 10:29:57 AM »

Quote
And, on the used market, a clean SB-220 / SB-221 with good tubes, sells for about $600 - $750...which is about the best bang-for-the-buck in HF amps....AND..
And, a pretty decent amp too...

OK if you dont want 160 and have to reduce power on 17/12 to keep from frying the bandswitch which is only available from those who convert the amp to 6 or 11M. Replacement original meters are almost unobtainium, the transformers are fragile and pricey from Hammond/Dahl, the relay is a clunky and usually mechanically worn out, the input network is from the 60's when tube exciters could drive them to full power and fold back with SS....and that is only a partial list.
I built them for two Heathkit stores, converted hundreds to 6M plus many repaired for others so I do have a bit of a history with them.

OTOH I consider the AL-80B a far better amp when run at 800W or less while the SB-220 family is really only a 1200W amp at 100W drive and less on 10M. I doubt if most hams would ever need an extra 1.76 dB except maybe for serious in the noise DXing on 80M CW

My own 2 x 3-500Z amp is an Amp Supply LK-500ZC which was partial payment for some consulting work and Ive had since 1986. It uses quality components on a par with Alpha and others, has been run hard in contests and DX chasing and with 80W drive (the IMD sweet spot of a TS-940 and many other 100W rigs) and still puts out 1200W, even on 10M, and has zero stability problems unlike the Heathkits. It also has full QSK with a vacuum relay. The only failures were a couple of leaky LV electrolytics on the QSK and PS board. All HV electrolytics were replaced at the same time and a noisy (not defective) fan was replaced with an all metal high precision EBM Papst 4600X, I added two speed selection for casual SSB operation with a D-104 and without headphones. It also has the optional external HD transformer as used on the LK-550. That combination still brings $1500-1800+ on Fleabay and a bit less for the base model.

Carl
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NN4X
Member

Posts: 56




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« Reply #51 on: February 11, 2018, 10:52:07 AM »

"Watts, are Watts, no matter how they are generated.."

Nope.  Not even close.





Although the focus are on various specification (IMD and so on), the power out was missed..

For most Ham operators, pulling funds from the family budget it a difficult one..!

Heath Kit SB220,..Almost 1500 Watts, and costs down to 500 - 800 (USD)...The solid state amplifier for 1500 watts, is very expensive.(No matter used or new..

Watts, are Watts, no matter how they are generated..

My point being, I hope someday the SS Amps are similar to the price break points when compared to Tube amps

I owned QRO 2500DX, SB 220, Kenwood 922 and Emtron DX3 SP...All of these costs no more than 1 dollar per watt..
Logged
KA4WJA
Member

Posts: 1098




Ignore
« Reply #52 on: February 11, 2018, 11:59:14 AM »

Karl,
We actually agree!!  Smiley
And, thank you for making me clarify things!

Yes, the AL-80b is a better amp than the SB-220/221...
And, yes, the LK-500 is a much better amp than the SB-220/221!  (actually had a buddy here locally that had one...and drove it with a TS-940, too...and not only did I see a well-made amp, but he found it to be very reliable!)

Forgive me if I implied that the SB-220/221 was a great amp....I was just saying that for those on a budget, and that don't need full-legal-limit / 100% duty-cycle, it's a good choice (in MY opinion, of course)



Carl, you do have much more experience with the SB-220/221 than I do (and I believe more than just about anyone here, save one of two others), so I won't argue the couple points that I'm not in agreement with you on.
....the input network is from the 60's when tube exciters could drive them to full power and fold back with SS...

<snip>

 an Amp Supply LK-500ZC.....
 has zero stability problems unlike the Heathkits.
I drove my SB-221 for years, with my TR-7 (a solid-state transceiver), without any SWR-foldback issues....and ,my best friend has been using my SB-221 now for over a decade, driving with his TS-130 (and also his TS-830, tube rig) for many years without any SWR foldback issues, and now uses his TS-590SG, with no SWR foldback issues...[yes, he did the "sof-key" mod, to allow modern rigs to key the amp]...
I suppose it's possible that some may have found the input to not be to the liking of their rig's output stage, but I've never seen it!  Smiley

And, unless someone drank the "kool-aide" about VHF parasitics, I've never seen or heard of any SB-220 instability??



But, whatever the case....
I think we are mostly in agreement, the AL-80b is a better amp....it's just that the 220/221 is a fairly good deal for many hams!  Certainly better than an AL-811 !!  Smiley


73,
John,  KA4WJA
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AF6LJ
Member

Posts: 4




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« Reply #53 on: February 11, 2018, 12:23:08 PM »

Sue,
We are all entitled to our own opinions and personal tastes...so no worries...Smiley


But, I completely disagree with you here.
In terms of IMD the modern FETs are comparable and in many instances better than vacuum tubes in terms of IP3.
You just can't beat the crap out of them like you can a vacuum tube.
Would you mind showing me these FET amps?  
And, their actual IMD tests?
Thanks.
Be sure to have a look here:
https://www.eham.net/ehamforum/smf/index.php/topic,100600.msg809648.html#msg809648
https://www.eham.net/ehamforum/smf/index.php/topic,100600.0.html



Oh, and for a rather lengthy discussion of IMD of transceivers / exciters, be sure to have a look:
https://www.eham.net/ehamforum/smf/index.php/topic,97093.0.html
https://www.eham.net/ehamforum/smf/index.php/topic,97093.msg1053647.html#msg1053647



73,
John,  KA4WJA



Last I knew we were talking about amplifiers not transceivers, it is rather well known the digital methods used to generate sideband signals in many of the newer radios (of the last twenty years) are dirty as hell.
As far as the amplifiers sighted go...
Otherwise I stand by what I had said above.

I will say this;
I do think it is silly to judge a component like a tube or a transistor, FET or otherwise by how it is used in a piece of gear that is engineered to such a low cost as most of the ham gear out these days.

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KM1H
Member

Posts: 5573




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« Reply #54 on: February 11, 2018, 12:48:10 PM »

Quote
I drove my SB-221 for years, with my TR-7 (a solid-state transceiver), without any SWR-foldback issues....and ,my best friend has been using my SB-221 now for over a decade, driving with his TS-130 (and also his TS-830, tube rig) for many years without any SWR foldback issues, and now uses his TS-590SG, with no SWR foldback issues...[yes, he did the "sof-key" mod, to allow modern rigs to key the amp]...
I suppose it's possible that some may have found the input to not be to the liking of their rig's output stage, but I've never seen it!  Smiley

The fold back depends upon the input coax length, where the input circuit was tuned, which bands, and where in the band it was being used. PLUS how bad the input coils tuning slugs slugs were overheated and the fixed mica caps changed in value or developed leakage.

I also own a TS-130 and it did fold back often into a SB-200 which uses the same type of inadequate input design. Since I didnt want to bother with the ATU that it came with; it now drives a SB-230 to an easy 500W up in the BR so I can keep an ear on DXpeditions or chat with a few friends. The TS-130 12V IMD is marginal at best and the -40dB range of the 8873 final is wasted.
It is mostly used on CW anyway.

I also have 4 TS-830's which have a real 6146B/S2000 IMD in the low -40 dB range. Three drive VHF/UHF transverters at the Class A milliwatt level with the finals removed and the other is on the amp repair bench since no amp misbehaving can hurt it. An ancient Lakeshore 6M TX only converter is now a full transverter with a loafing 7580R that I can control the power from almost zero to 130W to test conversions into a DL or on the air. IMD is mostly well below most amp tubes capability using modern screen and bias regulation and a slight NFB.

Quote
And, unless someone drank the "kool-aide" about VHF parasitics, I've never seen or heard of any SB-220 instability??

Yeah, that voodoo parasitics crap will live on forever. Angry  OTOH parasitic suppressors with the resistors way up in value or even cracked open will cause real parasitics plus the tank circuit itself is prone to HV arcs in the Tune cap and switch with or without the so called safety choke open. That old clunky relay is way too slow for most modern rigs. There are some simple fixes to work around the basic causes.
At least the IMD is decent Roll Eyes

Carl and NOT Karl
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G3RZP
Member

Posts: 1327




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« Reply #55 on: February 11, 2018, 04:08:20 PM »

Carl,


Quote
Yeah, that voodoo parasitics crap will live on forever.


Same as the Flat Earth idea - and about as valid.
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KA4WJA
Member

Posts: 1098




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« Reply #56 on: February 11, 2018, 08:11:53 PM »

Sue,
Sorry about adding a link to another discussion.  (thought in might be helpful to some)

And again, I have no issue with opinions.

1)  I simply asked if you could provide me with some info and test results on these "FET amps" that you wrote are comparable or better in regards to IMD, than most of the tube amps listed here?
https://www.eham.net/ehamforum/smf/index.php/topic,100600.0.html
https://www.eham.net/ehamforum/smf/index.php/topic,100600.msg809648.html#msg809648
Yes, some SS amps do have some comparable IMD products, to some tube amps, but most are significantly inferior. 
In terms of IMD the modern FETs are comparable and in many instances better than vacuum tubes in terms of IP3.

And, FYI to all, why do most only look at 3rd order products??  'Cuz in SSB service, higher-order products usually cause significant splatter.
 



2)  As far as SSB generation in newer radios?
In my HF and SSB experience, I've seen/heard some odd signals, but never heard of DSP-generated SSB causing poor transmit IMD, and except for some defect in the DSP, I can't think of how that would occur.
While I'm an analog guy (not a big fan of DSP, but I'm slowly coming around), I have to admit that DSP generated SSB is quite "clean"....it is the transmit PA that is causing the poor transmit IMD...
Last I knew we were talking about amplifiers not transceivers, it is rather well known the digital methods used to generate sideband signals in many of the newer radios (of the last twenty years) are dirty as hell.
As far as the amplifiers sighted go...
Otherwise I stand by what I had said above.




3)  Sorry about the misunderstanding.
I was not making "judgements", just provided the factual test data and we also discussed the other factors (like load SWR and power-supply regulation) that can have detrimental effects on amp IMD.
I do think it is silly to judge a component like a tube or a transistor, FET or otherwise by how it is used in a piece of gear that is engineered to such a low cost as most of the ham gear out these days.
But, just like others, you do highlight the point that cost is a factor here as well...




73,

John,  KA4WJA
« Last Edit: February 11, 2018, 08:17:29 PM by KA4WJA » Logged
KM1H
Member

Posts: 5573




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« Reply #57 on: February 12, 2018, 05:21:45 PM »

Quote
And, FYI to all, why do most only look at 3rd order products??  'Cuz in SSB service, higher-order products usually cause significant splatter.

Because they are technically dumbed down and brainwashed by the ARRL, equipment manufacturers, non peer reviewed web sites, and some poorly educated hams (or shills) to accept that is all that is important.

Carl

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KA4WJA
Member

Posts: 1098




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« Reply #58 on: April 17, 2019, 10:37:05 AM »

Some may balk at me posting again here, to bump this thread up...sorry...Sad

But, with all the recent talk of amps for FT-8, amps for some particular rig, etc...and those looking for reasonably-priced amp, etc...
I thought this might be useful for some to read..


73,
John,  KA4WJA
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