Specifications

RF section
Fig. 10 Fig.11
Fig.10 is the RF "tank" circuit for RF output. "D & C" points to the moving parts that should
be periodically treated with Pro-Gold®
. The stock plate choke is pointed by "A", and the HV
"glitch" resistor is "B".
Fig.11 shows the "tuned input", consisting of silvered-mica capacitors, and toroid coils. The
band-switch of the input network should be treated with Pro-Gold® also.
WARC bands?
The Alpha 86 is fully-operational on all the WARC bands, no modifications are needed,
provided the 10/12 meter bands have been enabled.
The domestic version uses the 15 meter section for 17 meter operation & 10 meters for 12
meter operation.
On the export version, the WARC bands fall within frequency ranges that also cover the
standard ham bands.
4CX800/GU-74B conversion?
I have done a feasibility study on conversion of the EIMAC 3CX800A7 tubes to the less
expensive Svetlana 4CX800/GU-74B. It is my opinion that this conversion would be far too
complex & expensive, if not impossible.
Here is my reasoning:
Available space inside the 86 is very, very limited. I don't feel that there is enough room to
install the necessary parts for the conversion.
The purchase of two GU-74B's & two sockets, the construction and installation of a well
regulated screen and grid-bias power supply, to name a few of the initial expenses.
The plate impedance would allow that no changes be made in the output tank circuit,
however, the input network would require radical alterations.