It's not my amp XXX, I just know the requirements for it. Sorry if I mislead you in any way. Amp was being sold by SmoothRadio912 and has been sold.
If you are looking for a decent amp for your 148gtl, I would recommend the TNT 350hd. If you can find an older one that is even better. The new ones aren't bad, and will work well with that radio as long as the dead key is lowered and the pep input to amp isn't too much. Here are the specs for the new TNT 350hd. They are made by Xforce. If it were me, I would stay away from the new Texas Star amps. But that is JMHO. Anyways here are the specs on the tnt 350hd.
Also depending on how many watts your radio does you can look at the cheaper RM Italy amps. Something like the KL300p or the KL203P. Neither require much drive and will blow if over driven very much.
The TNT 350hd cost much more. But is a better built amp IMO.
Also if you can find a magnaforce 350hd, which haven't been made for a while, they are good AM/SSB amps. Basicallylnmnmbbmm. Z they are the TNT 350hd in a different color casing and use toshiba 2879's. I have one and it will take some abuse. I don't use it much anymore but won't sell it due to the fact it has toshiba 2879's in it. Here are a couple of pics of it. Note how it is very similar to the TNT350hd. And also I included a couple pics of my TNT 600hd. It's an older one. Has toshiba 2879's as well. Made with the red dot type. The magnaforce has the older toshiba non red dot 2879's. Don't have time to pop the lids this morning as I have to head to work. But if you post a thread asking about purchasing one of these amps or one similar like the TS350hdv, you most likely will get a response or 2 I would think. Lots of people are getting out of the hobby at the moment due to the lack of DX.
The photos of the magnaforce 350hd will give you a good idea of how the TNT 350hd looks. Like I said, same amps, just a different case and different transistors were used as it's hard to get toshiba 2879's in bulk and keep the cost of these new amps somewhat reasonable. Hope this helps. And also you might try looking for a older palomar type amp that uses SD1446's or MRF454 type transistors. But again. The TNT 350hd will most likely be your best bet. Only other amp company I know of that is pretty good is BM Technologies. They make some nice amps as well. But aren't cheap. Also note how they look similar to the tnt350hd case. That is where the similarities stop though.
Hope all this helps and hope you find and amp. I would post a thread about it though and give as much info as possible as to how it and with what radio it will be used with as well as your antenna setup and so on. Again, hope it helps and sorry for the text wall. Have a good day.