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Kenrich Eagle 500-Next Patient
- Thread starter Dmans
- Start date
I have been trying to find schematic for eagle 500 but CB tricks web site has been taken down, if some has copy please email to me at djsmadal@gmail.com
Just don't use 20LF6 tubes in the two driver sockets.
The amplifier feeds around 27 Volts to the heaters. It was designed for an obsolete type 27LF6 that was rare when it was new. Only used in european TVs, never an american model.
Type 30KD6 will work. 20LF6 will flame out and toast the plate choke.
And themselves.
For that matter, the five final tube's heaters are wired in series, powered directly from the 120 Volt line cord. Five of the 27LF6 add up to 135 Volts in series. Running them from 120 or 125 won't cause them any harm. But five 20LF6 heaters in series only add up to 100 Volts. If your line voltage is 125 Volts, each heater will have 25 Volts on it, not 20 Volts.
Same hazard. Seems to me we used a 25 or 30 ohm 50-Watt resistor in series with the five final filaments to make the 20LF6 tubes behave in this model.
Excess heater voltage is only one reason this model tends to flame out, but a common one.
73
The amplifier feeds around 27 Volts to the heaters. It was designed for an obsolete type 27LF6 that was rare when it was new. Only used in european TVs, never an american model.
Type 30KD6 will work. 20LF6 will flame out and toast the plate choke.
And themselves.
For that matter, the five final tube's heaters are wired in series, powered directly from the 120 Volt line cord. Five of the 27LF6 add up to 135 Volts in series. Running them from 120 or 125 won't cause them any harm. But five 20LF6 heaters in series only add up to 100 Volts. If your line voltage is 125 Volts, each heater will have 25 Volts on it, not 20 Volts.
Same hazard. Seems to me we used a 25 or 30 ohm 50-Watt resistor in series with the five final filaments to make the 20LF6 tubes behave in this model.
Excess heater voltage is only one reason this model tends to flame out, but a common one.
73
Nomad,
There is something in the schematic for these amps that seems weird to me and i was wondering if you might take a look at it for me?
link: https://web.archive.org/web/2015032.../kenrich/eagle_500/graphics/eagle_500_sch.pdf
specifically i am wondering about the bias circuit right in the middle of the page.
you were the one who taught me about this, and to me, it seems weird that there is a
+15 volts going to one grid, and a -15 volts going to another grid.
is there a mistake in this schematic, or is it just something i haven't seen before?
might be doing something with mine finally, as i just scored a great deal on some tubes and a 6 volt transformer (20 amps).
LC
There is something in the schematic for these amps that seems weird to me and i was wondering if you might take a look at it for me?
link: https://web.archive.org/web/2015032.../kenrich/eagle_500/graphics/eagle_500_sch.pdf
specifically i am wondering about the bias circuit right in the middle of the page.
you were the one who taught me about this, and to me, it seems weird that there is a
+15 volts going to one grid, and a -15 volts going to another grid.
is there a mistake in this schematic, or is it just something i haven't seen before?
might be doing something with mine finally, as i just scored a great deal on some tubes and a 6 volt transformer (20 amps).
LC
Sold for $200 on ebay. I had the seller include inside pics. Maybe they will be of help.
https://www.ebay.com/itm/143532856930
https://www.ebay.com/itm/143532856930
seems like my amp has an IC where the other versions used a tube.
is this the CW portion of the amp?
here is a datasheet for the Motorola IC that is used in my amp:
https://www.jameco.com/Jameco/Products/ProdDS/24942.pdf
It's an IF amplifier.
this amp had a hard life before it got to me so there are some burnt traces and it looks like some jumpers where traces were peeled up.
in the last pic, you can see that the 1/4" jack for the CW key, and the crystal socket never had anything soldered to them.
I think the guy who used to work for Kenrich said this was more of a prototype, so hopefully i can make a working amp out of it.
LC
is this the CW portion of the amp?
here is a datasheet for the Motorola IC that is used in my amp:
https://www.jameco.com/Jameco/Products/ProdDS/24942.pdf
It's an IF amplifier.
this amp had a hard life before it got to me so there are some burnt traces and it looks like some jumpers where traces were peeled up.
in the last pic, you can see that the 1/4" jack for the CW key, and the crystal socket never had anything soldered to them.
I think the guy who used to work for Kenrich said this was more of a prototype, so hopefully i can make a working amp out of it.
LC
For sure David!
you know i won't be able to help but change or add something.
im hopeful that there are things on the boards i can just eliminate.
LC
The negative 15 Volts goes to the driver tubes' control grids, the grid closest to the cathode in the schemo symbol. This serves to limit the tube's anode current with low or no drive carrier.
The positive 15 Volts goes to the tubes' screen grids, the middle of the three grids in the tube. Serves to goose the tube's power gain.
73
thanks for that Nomad.
it will be nice not to have to add bias in like you showed me how to do with the kris power pump.
obviously my amp is a bit different from everyone else on the planet so i've got some things to figure out.
first is that all the other versions have four relays in them, and mine only has two.
mine also has an IC chip in it and i believe none of the others do.
for those that have the 'regular' kenrich design, you can just eliminate three of those four relays if you don't care about having a receive pre-amp. you can also get rid of the whole preamp section for that matter.
i will have to take a closer look and a better pic, but i believe that my voltage regulator board has a trimmer resistor on it, which might be for setting bias.
so many questions to answer...
LC
it will be nice not to have to add bias in like you showed me how to do with the kris power pump.
obviously my amp is a bit different from everyone else on the planet so i've got some things to figure out.
first is that all the other versions have four relays in them, and mine only has two.
mine also has an IC chip in it and i believe none of the others do.
for those that have the 'regular' kenrich design, you can just eliminate three of those four relays if you don't care about having a receive pre-amp. you can also get rid of the whole preamp section for that matter.
i will have to take a closer look and a better pic, but i believe that my voltage regulator board has a trimmer resistor on it, which might be for setting bias.
so many questions to answer...
LC
im just going to put this here so i can remember where to find it, and hopefully so can others.
http://www.steampoweredradio.com/pdf/stancor/1983 stancor transformer.pdf
this is a guide that will help you find the type of transformer you need by name.
it's very helpful when you need to scour ebay for months in order to find something.
LC
http://www.steampoweredradio.com/pdf/stancor/1983 stancor transformer.pdf
this is a guide that will help you find the type of transformer you need by name.
it's very helpful when you need to scour ebay for months in order to find something.
LC