HR2510 Pre driver question.

[Low_Boy]

Looking through some notes I have on changing the MRF-477 on a HR2510 over to a pill type final.
It says change predriver Q134 to a NTE 340 wich is practically nonexistent. Is this a typo. Or am I wrong. I always thought that the pre driver is Q124 a 2SC1973.
Anyway does this step really have to be done? I have a radio here with a MRF455 and Q124 and Q134 are factory and the radio works with no problems.

EDIT I did not look close enough. the radio has a 2SD1446 for a final.

 

[nomadradio]

NTE340 is a terrible idea for Q134. It's a VHF transistor meant for 150 MHz. Has way too much gain for this radio.

An article in 73 magazine almost 40 years ago described a so-called upgrade from the MRF477 to the MRF497 final. Changing Q134 was part of the picture.

It should increase the drive level to the driver stage, but we found it to be unstable in that circuit. Had a tendency to oscillate. Made sideband transmit audio sound like poo.

I suppose you could reverse-reference the original part that the NTE340 was sold to replace. NTE never made the parts they sold, but only scraped off original numbers to print their own on the part.

Good chance that if you took the NTE cross-reference book and started on the page with "2SC" numbers you would find one that crosses to NTE340.

Never tried.

No good reason.

73

 

[Chevboy0167]

I would love to get my hands on that nice and neat nifty solder in 455 board that went around yrs ago. Ohhhhhh... I have a pair of old skewl 2879s here begging to be used! LOL

 

[Low_Boy]

Nomad if from the factory Q134 is a 2SC2086 and Q124 is a 2SC1973 and the radio is working fine Probably go with the transistors Uniden originally installed in this radio.

So actually just trying to figure out what some one else did. My first posting was wrong. For a final they installed a 2SD1446 and the radio is set for 50W AM and SSB and looks great on the scope. I have been trying it out for a couple weeks now. I have not even cranked it much past this point because I think those are very respectable numbers for this radio.

 

[nomadradio]

2SC2086 is from Mitsubishi. The 2SC1973 is a Panasonic product.

Specs are incredibly similar.

Looks as if each part was designed to compete for the same design market, to be used in the same kinds of product.

73

 

[kopcicle]

NTE340 is a terrible idea for Q134

Been there, done that, burned the T-shirt.

 

[711]

I would love to get my hands on that nice and neat nifty solder in 455 board that went around yrs ago. Ohhhhhh... I have a pair of old skewl 2879s here begging to be used! LOL

Using my Lincoln for my template , gonna roll my own for a few HG 454’s I got

 

[sp5it]

No need to change predriver.
Do it like described:
http://rogerbird.tripod.com/betterp.gif

 

[Low_Boy]

No need to change predriver.
Do it like described:
http://rogerbird.tripod.com/betterp.gif

Yes and still works fine.

So what is Q132 and what is Q124? Which is actually the pre driver and what is the other part? Sounds like a odd question but.