Do I need an Antenna tuner with a Hybrid rig?

[KF7RDY]

I'm looking at getting a HF rig. I found a guy selling a Kenwood TS-820.

Reading on the Web, I find referances to the old Tube and hybrid rigs not needing an Antenna tuner, is this true?

If I understand it, you can adjust the final's "on the fly" to adjust the SWR for a match. Or am I just completely confused?

Sorry about any spelling or grammer mistakes, I'm pretty sick.

[KL7AJ]

This depends on how good a match your antenna is. I always use a good antenna tuner whether I need it or not, but that's mainly because I have a few of them and I don't want them to feel ignored. A good hybrid rig can usually safely match any load less than about 5:1 SWR. YMMV

Eric

[KF7RDY]

I've got an 80m dipole currenty, and i wouldent be opposed to putting up one or 2 more.

[KE3WD]

The tube outputs of the hybrid rigs does indeed allow for a certain amount of tuning, as already mentioned, typically one can match up to around the 5:1 area without need of a tuner.

My advice to you is to try it on your antenna and find out what freqs it will match. Then decide if an outboard tuner may be of benefit.


73

[K9STH]

The pi-network used in tube-type final amplifiers can definitely match a wide range of impedances. Depending on the actual design, it is possible to match up to at least a 40:1 SWR!

I have transmitters that can match from about 300 ohms (6:1 SWR) all the way up to over 2000 ohms (40:1 - my Hallicrafters HT-20). That is why I don't even own an antenna tuner!

Glen, K9STH

[KF7RDY]

Cool to know. That clears up some worries I had.

[N2EY]

It depends on the situation.

SOME rigs with tube finals can match almost anything. Others have a decidedly restricted range, and it usually varies from band to band, and with the nature of the load.

FOr example, you can have a 5:1 SWR because the load is 250 ohms of pure resistance, 10 ohms of pure resistance, or an infinite number of combinations of resistance and reactance.

The best advice is "try it and see"

73 de Jim, N2EY

[KA4DPO]

The pi-network used in tube-type final amplifiers can definitely match a wide range of impedances. Depending on the actual design, it is possible to match up to at least a 40:1 SWR!

I have transmitters that can match from about 300 ohms (6:1 SWR) all the way up to over 2000 ohms (40:1 - my Hallicrafters HT-20). That is why I don't even own an antenna tuner!

Glen, K9STH

I also have some pre 1960 gear that can load the bed springs Glen but he is talking about a hybrid rig. I have never seen a hybrid rig that match more than 3 or 4 to 1. The Kenwood Hybreds will match from 25 to about 150 ohms and that goes for the Yaesus from that era as well. Even the older all tube tranceivers of the 60's did not have a huge matching range.

[KD5TXX]

Let me be the new guy to ask the obvious question....How exactly do you tune it? I have an820 also. I use a tuner and tune up the rig to an already low SWR. If I took the tuner out of line, what would I do to get a match? Would it be the load knob?

[K9STH]

You have to "adjust" both the "tune" and the "load" capacitors.

Glen, K9STH