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Cell phone signal amplifiers pengyou The Tech Zone 26 07-14-2018 05:48 PM

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Old 03-09-2019, 05:00 PM
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Originally Posted by CPLSeraphim View Post
I just bought a 1200W amplifier. Tube style. May need some basic fixes, but at least I have a guy who can go over it with me. I made an offer, and the seller accepted. More that I was looking for, but again, the guy is not a ham. Gamble? Yes, Either way, almost guarenteed to be fixable. The tubes still glow and appears to function. I'll get back to you guys on it when I find out more.
Thank you for your time.
Make, model? Price? Pictures!!!
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Old 03-15-2019, 08:05 AM
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It is a swan 1200W amplifier. I will post pictures and additional information when it arrives. Just waiting for it to come in. gotta see which tubes came with it. I will be ordering new on shelf tubes, no matter which tubes it has, however, I hope it has the harder to find tubes because, from what I have found, it just works the best...
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Old 03-16-2019, 09:18 AM
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Originally Posted by CPLSeraphim View Post
It is a swan 1200W amplifier. I will post pictures and additional information when it arrives. Just waiting for it to come in. gotta see which tubes came with it. I will be ordering new on shelf tubes, no matter which tubes it has, however, I hope it has the harder to find tubes because, from what I have found, it just works the best...
Hmmm, the Swan 1200W is an interesting amplifier, I had one years ago. Definitely lower end than say a Heathkit SB200 or a Yaesu FL2100, but also pretty simple and should be easy to work on.

The Swan 1200W originally came with 6LQ6 tubes. These are TV sweep tubes that were in common use for amplifiers for CB radio, less commonly for ham radio. Several other tubes, all TV sweep tubes, can be used in the amplifier with little or no modification (depending on the exact tube). 6JE6C, 6ME6, 6MJ6, etc.

The Swan 1200X amplifier came with 8950 tubes, and could be pretty easily modded to take the lower cost, and more available, 6KD6 or 6LB6 tubes. 12LQ6 tubes were even easier to swap in, but those tubes are pretty rare these days.

What can you expect with a well working Swan 1200W?

The input power is 1200 Watts on SSB, as the name implies. This equates to a real world output of 400 to 600 Watts PEP SSB, depending on the band of operation and the specific tubes. The amp is rated at 800 Watts on CW, but that is pushing things a bit, and more like 400 Watts PEP or less is probable.

The amp will get really hot, really quick, running near max powers. Forced air can help this situation a lot, but you have to give such a modification a bit of thought to avoid high fan noise (which is often picked up by the microphone) or the tubes picking up mechanical vibration.

If I remember right you will need to drive this amplifier with a bit under 100 W PEP to get full rated output.

As I said above, the 1200W (and lots of lower end amplifiers aimed more or less at the CB market) originally used TV sweep tubes instead of "real" RF amplifier tubes. Back in the day these TV tubes were available really cheap, like under $3 each at any corner hardware store, and they worked almost as well as the purpose built $20+ amplifier tubes. So for a modest performance hit a sweep tube amplifier could cost a lot less.

Today the 8950 tubes of the 1200X have not been made in many years, and can cost a couple hundred a piece for NOS, when you can find them, and low cost 6LQ6 tubes for the 1200W can be over $10-30 for working used tubes, with NOS running well over $40 per tube. I have an old silver face Phantom 1500 that uses 12 of the 6LQ6 tubes, to re-tube that today can cost me over $500. Fortunately I have a lot of tubes on the shelf. The 12LQ6 I briefly mentioned above as "rare" today can go for hundreds of dollars a piece for NOS / NIB, and remember it was originally selected for these applications because it was a very low cost option.

Some RF amplifier tubes are still made by various companies today. But the old TV tubes are generally not still made. This can lead to a reversal of the original prices, NOS TV tubes can cost more than NOS RF tubes. For example 811A tubes can be had for less than 6LQ6 tubes.

T!
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