my new tube FM preamplifier

[radioactive]

well here it is a ameco nuvistor cascode fm preamplifier using a pair of 6ds4 nuvistors. i didn't get a chance to hook it up yet but thought i'd show it off anyways i've been looking for other tube preamps that cover the fm band that were built by manufactures like ev and others but this is the first nuvistor one that showed up so i grabbed it until i can find the one that im after.

 

[dshoaf]

IIRC, that's a signal booster that would go between the antenna and the tuner, right?

I built an Ameco ham transmitter as a kit back in the early 70s. It was simple, did the intended job and solid - as long as you had good soldering skills.

Cheers,

David

 

[spaceman]

Pretty interesting, I never even heard of those. I figure it must have been for folks who lived out from town a ways, I generally get great reception on tube receivers & tuners, often with no antenna.

 

[radioactive]

IIRC, that's a signal booster that would go between the antenna and the tuner, right?

you are correct dshoaf.

Pretty interesting, I never even heard of those. I figure it must have been for folks who lived out from town a ways, I generally get great reception on tube receivers & tuners, often with no antenna.

actually they go back to the 50's and are along the same lines as the ones they had for tv but covering the fm band. the fm ones are rarer than the tv ones for obvious reason. electrovoice made one for fm that i'd love to find.

http://www.hifilit.com/hifilit/Electro-Voice/119-8.jpg

:drool:

 

[dokblues]

Very nice there Chris! Man I will have to keep my eyes open at the Estate sales for the EV. Lots of old folks out west here.

 

[mhardy6647]

Nuvistors were really good for applications like this.

 

[radioactive]

Nuvistors were really good for applications like this.

yes they were and thats why at the end of the tube era many tuners could still be found with nuvistor front ends

 

[mhardy6647]

Well, that plus the fact that transistors that worked well at VHF weren't really available yet...

 

[wa2ise]

Ameco was a significant maker of ham radio equipment back in the 50's and 60's. Your FM preamp looks a lot like their 2 meter ham band (144-148MHz) and their 6 meter ham band (50 - 54MHz) preamps. The only difference really is the passband frequencies.

 

[Wavebourn]

I heard that when Desert Storm in Kuwait started R390/URR receivers were pulled back from warehouses to fields because transistor input stages in preselectors were jammed by lots of transmitters and other RF interferences. Still, nothing can beat tubes when narrow frequency band needs to be selected from the ocean of signals.

 

[Sam Cogley]

yes they were and thats why at the end of the tube era many tuners could still be found with nuvistor front ends

I gutted a Fisher 600-T solid state receiver. It had three tubes, all in the FM front end - two nuvistors and one tiny little glass tube.

 

[wa2ise]

I gutted a Fisher 600-T solid state receiver. It had three tubes, all in the FM front end - two nuvistors and one tiny little glass tube.

Reminds me of the agony I had dealing with my el-cheapo FM stereo receiver I got for high school graduation. Had no tuned circuit on the RF amp's input, which was a bipolar transistor. Intermod up and down the dial (Lived in a suburb of New York City). Replaced it with a JFET, and it helped a lot. I imagine a tube would have been better yet, but mucking around with 100MHz circuitry is non-trivial. Transistor local oscillator, and tube RF amp, and maybe the mixer should be a tube as well.