Magnum S9 1916 Finals vs Mosfet

[ihv800]

Hey guys, I'm interested in getting into a Magnum S9. Used looks to be the only way to go, and I'm seeing that the earlier models used bipolar 1969 finals, newer models used mosfets. I've done a lot of reading on this, but do not fully understand the good and bad between them. Seems some guys swear by the older models (better reliability/performance), and others are happy with the mosfet models. Just looking for some insight from minds more familiar with this stuff about the good and bad between them? Is it worth seeking out the older model, or will any well taken care of unit serve me well? Also wondering if there is any info on the future of Magnum and if new model radios are down the road?

 

[BigKahuna]

I myself prefer the older S-9 with the 1969, but it's just a personal preference as I had one that really performed great and is still working good 8 years after I sold it to a friend.

I've owned plenty of radios with mosfets, they tend to be a little more finicky but nothing wrong per se with them. I think the 1969's finals were just able to handle people's golden screwdrivers better than the mosfets. I do notice that the mosfet radios seem to get hotter quicker than the 1969 models.

 

[ihv800]

I've read lots of people having similar thoughts to that. By handling peoples golden screwdrivers, you mean the 1969's coped better when the radio was tuned for more output? Or coped better with improper tuning? Thanks for the input!

 

[Robb]

I've read lots of people having similar thoughts to that. By handling peoples golden screwdrivers, you mean the 1969's coped better when the radio was tuned for more output? Or coped better with improper tuning? Thanks for the input!

No; the MOSFET will put out more. So, they don't need to be tweaked to get more power. MOSFET radios put put more power right out of the box. Replacing bipolar transistors is also more expensive than replacing a MOSFET. Some say that the impedance issues with the MOSFET make it a bit less desirable, but I haven't found that to be too great of an issue. Either S-9 is a question of choice. Have worked with both of them and saw no real difference except output.

 

[222DBFL]

I have found that like said, Mosfets don't like a bad VSWR or impedance mismatch. I know that my old magnum 257hp was very prone to acting funny if the VSWR of the antenna system was more than 1.3:1. My old radios that use 1969 final radios didn't act this way. Also like said, the Mosfets do get hotter then the 1969 final does.
As far as power, like said, I have seen more power come from a Mosfet radio, but at the cost of a lot of heat. And also I am in the same belief that the 1969 bipolar transistor is a more rugged transistor, but they are more expensive to replace for sure. A dollar or 2 for a Mosfet. If that. A lot more for s 1969 bipolar transistor. And also the power increase isn't worth just taking out a good 1969 final and replacing it with a Mosfet unless you just like to see the meter move a bit more. You need 4 times the power to get a 6db increase or basically 1 s-unit of signal increase to a receiving station.
My motto is, if it's not broke don't fix it!! Most replace radios like said with Mosfets after a 1969 final has blown, as its way cheaper in the end to do so. Parts are super cheap and readily available. JMHO. The gents that posted before me know 100x what I do, but I do have a few radios, so most of what I have gathered has been through experience of using, and not repairing or even just messing with radios. I let the pros do that!! I can do simple things with the tools I have, but I am no tech by any means as far as radios go. At any rate, hope this helps and have a good day.

 

[ihv800]

Fantastic info, thanks for sharing guys, just what I was looking to find out! I understand about the SWR being a bigger concern with mosfets, but could you go into a little more detail on the issue of impedance mismatch?

 

[9C1Driver]

Hey guys, I'm interested in getting into a Magnum S9. Used looks to be the only way to go, and I'm seeing that the earlier models used bipolar 1969 finals, newer models used mosfets. I've done a lot of reading on this, but do not fully understand the good and bad between them. Seems some guys swear by the older models (better reliability/performance), and others are happy with the mosfet models. Just looking for some insight from minds more familiar with this stuff about the good and bad between them? Is it worth seeking out the older model, or will any well taken care of unit serve me well? Also wondering if there is any info on the future of Magnum and if new model radios are down the road?

Used is the only option you have since the S series of Magnum radio's have been out of production for years. The S9 is a super radio, dual 1969 would be my first choice but at this point any clean and properly functioning S9 at a fair price should be snapped up. E-Bay would not be the best place to look, they are bringing stupid money there.

 

[222DBFL]

Your radio system is a based on a 50ohm system. If you have a mismatch that is bad enough it will cause issues. This will normally correlate with a VSWR issue, but can be off and still present a good VSWR as well. There is more to tuning an antenna than just getting the VSWR low. It took me a while to understand this, but unless you have some type of matching system, which most base or coil antennas have, you're impedance can be off. Same on a base antenna. I have seen VSWR be 1.1:1 but the impedance be at 60ohms. This isn't so bad, but it can change and if it gets too out of whack, it will cause issues. I might not be all the way correct in what I am saying, but I know what I have seen while using an antenna analzyer versus just using an swr meter. Like I said, there is more to tuning an antenna than just having a decent VSWR. Hope some of this info helps. Have a good day.

 

[ihv800]

That's very interesting, I have not heard of that aspect, but it makes a lot of sense. I'm guessing that impedance issue is the reason good SWR is critical in a mosfet radio. Good info, thanks for sharing everyone. The differences make much more sense now!