The Low Band Challenge

Trying to build a great DXing antenna on the Low Bands (on a small suburban lot) is quite a challenge. I’ve tried many different things – verticals, phased verticals, shortened top loaded verticals, full wave linear loaded Delta loop on 80, “Mod Bob” using a Palstar BT1500a, switched base loading Inverted L, and more.

And don’t forget the RX antenna – that has taken me a year to experiment for – and with the Wellbrook ALA1530LNP loops phased through the DX Engineering NCC-2 is one of my best antenna accomplishments.

40 meters has always been easy. My DX Engineering DV-40-P is one of the top 3 antennas I’ve ever owned. It’s radial field and siting are perfect (although if you saw it up close you’d not believe it). 160M has been somewhat easy – because I only needed the CW portion of the band.

80 and 75 Meters are a real bugger. I’ve finally come to the conclusion that the best one can do on a small lot is put up one Spiderbeam 60′ fiberglass pole (the 70′ version is $200 more – not worth the money) with wire taped to it and either use relays to switch in different lengths of linear loaded wire or use a Stepper motor to tune for resonance. Another option is to tune for the 80M CW band and then use an in shack tuner for 75M.

My KPA-500 has never liked 80 or 75M. It has had an overshoot problem and also has seemed extra “sensitive” on 75 / 80M. It has been fine on 160M and all other bands. I’ll have to send it in. My K3 and KAT-500 have been fine – it’s just at even more than a couple hundred watts, 75 and 80 get squirrelly. I’m sure it’s a high voltage situation.

One answer is to tune for a small segment on 80M and simply not use the amplifier on 75M. The vertical would be 70′ for 80M and 63′ for 75M. I’ve learned that that makes for a huge difference in impedance at the base.

I think I’ll opt to tune the vertical for 80M and only use the amp for CW, since that’s where the DX pileups are. The net I check into at night, where I never pass traffic, deserves no more attention than 100 watts – hi hi.

So, the low bands really “test your meddle” like no other bands do – both antenna construction wise and then operating wise (at least on the West Coast where EU and AF are considered big catches – a far different cry than for East Coasters).

Its funny how much easier 40 and 30M are compared to 160 and 80M, but I love these challenges, as frustrating as they can be.

2 Comments on “The Low Band Challenge

  1. Rich, why not try fixed tuners for 75m SSB and 80m CW at the base of the vertical?

    Frank PA7F

    Like

    • That’s a great idea. In fact, cut the wire for 80M and remote tune for 75M, using stepper motors.

      Like

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

w

Connecting to %s

%d bloggers like this: