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Author Topic: Hercules II Restoration  (Read 2838 times)

Posts: 2

« on: January 23, 2005, 10:29:09 PM »

Hi Everyone,

I posted the following message on the Ten-Tec reflector, without success. Perhaps there's an OM who can help. Here's my original message:


I have recently obtained a Hercules II amp (serial # 09A10034) that does
not seem to work right. It came from Cameroon in Africa, via a ham friend. The
amp was in commercial use. I'm evaluating it, and am considering to purchase
it if I can get it to work. I cleaned the amp, inside and out, and apart
from two blown panel lights, a missing plastic trim-piece and broken fan
everything appears to be visually intact.

There was a non-standard board connected to the Remote Control socket. It is
constructed on Vero Board (strip board) and contains two IC's UDN2981A and a
Philips PC74HCT238P. It was mounted on the ledge behind the Keying RCA

I have removed the modification (as Ten-Tec advised), and reconnected the 8
wires that lead from the remote port. I simply matched the colors.

The modification also included two wires (orange and green), one each to J41
and J42 on the Input Board (Top of Heatsink). I cannot figure out how to
restore proper wiring to these connectors. Although J41 and J42 have two
pins each, only one pin was used.

There is a black chassis-earth wire and a red fused wire still unconnected,
but I'm not sure if they were simply part of the mod, or if they go to J41
and J42.

Also, J9 on the control board has no connection. On the bottom of the amp,
on the bandswitch board, the connector between J11 and J10 is also
unconnected. It is a two-pin connector.

When I turn the amp on, using my Astron RS-35 for no-load testing, the fan
comes on and the relays on the Power Distribution Board pull in. But the
Band LED's are unlit, although there is power on the connector on the board
with the band switch. When I select different band positions, nothing
happens. The relays on the filter board are silent, and all LED's remain
unlit. I found 13VDC on some connectors on the filter board.

I have been in contact with Paul Clinton at Ten-Tec via e-mail and
telephone. Bottom line is that a technician has to see the amp and trace the
wires in order to restore it. I ordered a manual, trim-pieces and spare
lamps, and should hopefully have it within 2 weeks. I will then be able to
trace the wires with the help of the schematic diagrams.

In the meanwhile, I'm wondering if a knowledgeable OM has come across this
mod, and has accurate advice on how to restore proper function to ye olde
Hercules. Thanks!

I have uploaded some pictures showing the relevant detail at:

TU 73 Christian ZS1DX

Posts: 10248


« Reply #1 on: January 24, 2005, 06:57:27 AM »

The home brew board on the back was probably a mod to allow keying the amp with one of the later model rigs that will not handle the 100 mils or so the amp requires to key up.

I suspect the reason the bands don't switch is because the wiring that switches between local and remote control is messed up.

I've never owned one, but I recently worked on one. Having looked at the schematic, I'm sure it is adequate to repair the wiring.

The only caution is the finals. MRF458s are hard to find and expensive when you do find them. Early models of the Hercules II can not be upgraded to replacement finals, later models can. If memory serves the replacement finals are 2sc2269s, but I'm not positive. TenTec is you source of info about this subject.

Alan, KØBG


Posts: 2

« Reply #2 on: February 10, 2005, 12:46:32 PM »

Thanks to all who replied! Here's an update: The Hercules II is working FB now. The main problem was a cut track on the band switch board. The amp was modified to only work  in the "remote" position. After reconnecting the track, and removing the mod, all works well now. 550W+ out on all bands. I used a 120AH Lead Acid battery for testing. I'm very impressed with the quiet, effortless operation of the Herc II. 73 to all. Chris
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