[TowerTalk] Looking for a HP 80/40 Duplexer

[Randy Farmer]

I appreciate all the feedback I'm getting on my query. To provide 
context, here's a brief description of how my station is organized:

Since moving to North Carolina from Texas in early 2020, until recently 
my antenna complement consisted of two wire antennas. The first is an 
80-40 inverted vee at about 50' center height. This consists of a common 
center insulator/balun  (DXE 5kW) with separate 80 and 40 meter 
elements. This antenna is fed to a 500W LBS 80-40-20 Triplexer (the 
original antenna design also had a 20 meter element, but it never worked 
very well). The station antenna switching control also allows bypassing 
the Triplexer and feeding the antenna directly to the antenna switch so 
the inverted vee can be used on the WARC bands. The second antenna is a 
Hy-Power 20-15-10 dipole (3 separate dipole elements arranged in a cage 
configuration with a common feed) at about 25'. This tri-band dipole is 
fed to a 500W LBS 20-15-10 Triplexer to provide isolated outputs for the 
three bands.

The six antenna ports available from this arrangement are switched by a 
microHAM Double Ten 2X10 switch to allow SO2R capability. The A and B 
outputs of the antenna switching assembly  each feed the Antenna port of 
an Elecraft KAT500 ATU unit, which is used as a  "line flattener" for 
the normal contest bands and as a tuner for the WARC bands. The ATU 
Transmitter ports feed the A and B Antenna ports of a TX BPF assembly 
consisting of a bank of six LBS 500W bandpass filters with a KK1L design 
2X6 switch at both input and output. This provides an interlocked TX BPF 
selection for both radios. There is also provision for bypassing the 
filter bank for use on the WARC bands.The two BPF Transmitter ports are 
in turn connected to the RF output ports of their respective KPA500 
amplifiers.

The station RF components have been carefully engineered to maximize 
isolation between the two radios. Double shielded coax is used 
exclusively and much attention has been paid to layout to minimize 
coupling. Each receiver chain has protectors in both the Main and Sub RX 
antenna inputs. I can operate either radio within about ±20 kHz of the 
other radio's second harmonic in SO2R mode at 500W output.

In September of this year I finally completed the installation of a JK 
Mid-Tri 40 on a 70' crankup tower. The triband portion of the JK is 
split using a LBS 1500W 20-15-10 Triplexer. The resulting 40, 20, 15 and 
10 meter ports are then switched using a 4O3A 2X8 switch. This hardware 
is located in a detached garage about 120' from the house. The A and B 
outputs from the 2X8 switch are fed to the entry panel at the house by 
1/2" hardline runs. The antenna switching assembly in the shack was 
modified to allow selecting either the local or remote feeds to the ATU 
Antenna 1 and Antenna 2 ports,respectively.

I had originally intended to keep the station at the 500W level, but 
operating Sweepstakes and CQWW SSB using a decent antenna has convinced 
me that if I really want to be competitive in the High Power class of 
the various contests I need to make up the 4+ dB power deficit to the 
full power stations. The $/dB investment is rather breathtaking, but I 
think I'll bite the bullet and do it. I'll probably upgrade only the 
Radio A amplifier, since the vast majority of my operation is SO1R mode. 
In researching available RF hardware to handle the increased power, I 
found a source for the high power bandpass filters, but not the duplexer 
and triplexer. It appears VA6AM will build the multiplexers I need. I 
didn't realize this, so I greatly appreciate the recommendations. I'll 
definitely contact him and see what can be done. Again, thanks to all 
for your assistance.

73...
Randy, W8FN