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Title: Amp recommendation: Viking T-bolt vs. HK Warrior Post by: KD2AZI on January 02, 2020, 04:20:29 PM I have two amps available, and I have no experience using either of them. I've scoured online posts, and eHam.net reviews about the Viking Thunderbolt and the Heathkit Warrior. Both are in great shape and I've refurbished the Viking.
Do you have any suggestions, pros/cons of which one to use for my ART-13 setup? tnx! Happy New Year! Title: Re: Amp recommendation: Viking T-bolt vs. HK Warrior Post by: DMOD on January 02, 2020, 04:37:50 PM Since I am a fan of 4-400's I would use the T-Bolt for AM. The Warrior with its puny 811's pales in comparison.
Pages 12-15 describes how to feed and load up the T-Bolt for Class AB2 operation. Phil - AC0OB Title: Re: Amp recommendation: Viking T-bolt vs. HK Warrior Post by: MikeKE0ZUinkcmo on January 02, 2020, 05:17:42 PM +1 for the T-bolt. Johnson works on all bands, and since your familiar with it....
Title: Re: Amp recommendation: Viking T-bolt vs. HK Warrior Post by: kb3ouk on January 02, 2020, 07:06:52 PM My opinion, neither. The ART-13 alone does at least 100 watts by itself, you could probably easily get 150 out of it with some care. The 811As in the Warrior only give you 260 watts of dissipation, so for AM without stressing components too hard you would only comfortably be able to get about 125 watts or so from it. The Thunderbolt's 4-400s will give you 800 watts of dissipation so would probably be good for a maximum of just under 400 watts of carrier. However, it sounds like that amp only does about 1000 watts ssb, so on AM you would be running around 250 watts. By that point you are only 3 db over what the ART-13 does alone. Plus the Thunderbolt is grid driven so you would have to run either reduced plate voltage on the ART-13 or an attenuator, since it doesn't need much drive.
Title: Re: Amp recommendation: Viking T-bolt vs. HK Warrior Post by: K1JJ on January 02, 2020, 07:35:30 PM Yep, agreed. The ART-13 is already in the AM league of those linears. It's all about the better efficiency of the ART-13's class C AM operation.
Usually we look for at least 6DB of gain to make it noticeable and a worthy improvement. That is four times the power increase which is a 600 watt carrier. (4X 150 watts) You would be better off refining the ART-13 and letting it run alone. Then use the linears using a ricebox driver as intended. Then look to build up a bigger AM plate modulated rig like 813s X 813s or whatever - like W9JSW is doing here in his thread. Or a 24 MOSFET class E AM rig is a great choice. BTW, if you were to use a linear like say, a 3CX-3000A7 (3 KW diss tube) or equivalent, then the ART-13 would be at a suitable driver power level. (about 10 DB of bigger carrier) Though you would need to clean up the audio which will take some work. Good Luck - T Title: Re: Amp recommendation: Viking T-bolt vs. HK Warrior Post by: KD2AZI on January 03, 2020, 10:08:04 AM Quote at least 6DB of gain Yes, so I would need an attenuator, so I get it, I'm attenuating way down to get the 6DB of gain as a best practice - so why bother. I should have mentioned that my Tbolt has PL-175s, and from what I'm reading and tube data that this doesn't make much difference in the equation over 4-400s. Thanks gents for the input! Title: Re: Amp recommendation: Viking T-bolt vs. HK Warrior Post by: w4bfs on January 05, 2020, 09:50:54 PM the T-bolt as well as most EFJ transmitters tend to have too much trapped heat ... Timtron has the real fix for these .... large quiet muffin exhaust fan on the back panel ... smaller quiet fans underneath .... ditch the impeller fans
its a lot of work but convert to grounded grid with vacuum c1, bigger inductor more B+ .... I have gotten 1600W out with 4-400 pulls .... good audio reports Title: Re: Amp recommendation: Viking T-bolt vs. HK Warrior Post by: Opcom on January 09, 2020, 03:37:40 AM Yes vacuum C1 as the HV rating of the caps leaves little room for increased voltage. My thunderbolt had blown the plate transformer and a 'properly' rated external one was almost twice the size. The same voltage was kept though. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
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