what are some differences between early and later versions?
fisher newbie
- Thread starter ceylon
- Start date
thanks buddy. welcome to AK!Welcome to AK.
Did a quick look-see
on this "Fisher", and
WOW! Lots of glowing
good comments on
this older '60's unit.
Lots of info available
online.
Good luck on
your receiver!
Q
im excited for the opportunity to do this restoration. ive never done anything so complex as a
receiver, but find the expertise and here AK to suit me quite well.
Quadman2
Lunatic Member
Just take your time.
See if there's any local tech pro's to help out if needed.
You could do more bad than good.
Been there.
Done that!
Q
im not very fast
nope
yeah, that would suck.
i havent wrecked anything yet, thankfully, but this is much more complex that push pull power amps or SE and stuff like that.
thanks buddy
ceylon. Most of the work (99 & 44/100%)on the 400 will involve the Power supply and Audio circuits. A couple resistors and caps between the end of the tuner and the multiplexer is basically it on the tuner section. The most involved and most worked section is the POWER SUPPLY, with the tone and preamp circuits a very close second. We can walk you thru it.
Differences in the early vs. late versions is a change in the tuner circuit and tube count. Early has 5 RF/IF tubes (V1 thru V5), while the late has 6 tubes (V1 thru V6). Output transformers are different spec (impedance 6.6K early, vs. 10k late). The Early model impedance is a dead on match for the output tubes. The late's can be upgraded to the early transformers, provided changes are made in the Negative feedback circuits. I have both, and prefer the early one (a bit simpler, even tho they are the same basic unit).
Differences in the early vs. late versions is a change in the tuner circuit and tube count. Early has 5 RF/IF tubes (V1 thru V5), while the late has 6 tubes (V1 thru V6). Output transformers are different spec (impedance 6.6K early, vs. 10k late). The Early model impedance is a dead on match for the output tubes. The late's can be upgraded to the early transformers, provided changes are made in the Negative feedback circuits. I have both, and prefer the early one (a bit simpler, even tho they are the same basic unit).
roger that. very good to know, im im happy to learn of that better spec on the early OPTs.
it will be a long time before i am ready to begin, but i would like to learn more about some of the different aftermarket restoration and upgrade materials and boards, then make my dewcisions about what course to take, then start buying materials. so far i only know that i do wish to be about to individually bias the tubes.
Last edited:
but i have the early version with the preferred transformers, so why change them, right?
No need to change the trannies on the early's (except when they chernobyl....and they very RARELY do).
Thanks Dave; I forgot EFB enhanced the power on the Late's. Pushing 70 sucks!
Larry
Thanks Dave; I forgot EFB enhanced the power on the Late's. Pushing 70 sucks!
Larry
I know.
EFB for the early version is discussed here:
EFB and Fisher 800, 500 & Early Version 400 Receivers
With the X-1000 project showing light at the end of the tunnel now, I thought I would take a moment to update the results of my work regarding EFB(tm) operation, and the 7591 family of output stages as typically used in these and about a bazillion other Fisher, Eico, Scott, and other...
audiokarma.org
hey buddy happy new year! its all on standby. i havea good few projects ahead of this one, but so i havent bought parts other thn hayseed hamfest capcitor kit and IBAM, vol buffer.
