VHF lo band propagation, unlike HF, doesn't happen every day. There are certain ionospheric (and sometimes weather) conditions that cause VHF lo to propagate further than normal.
But let's start with the antenna. I would check the connection to the fiberglass whip to make sure you have a good solid connection. The A99 used a series of tuning collars to make it resonate on the 27 Mhz band. Just connecting to the fiberglass whip does not disconnect the tuning circuits that are below it. To just use the whip you would need to physically break that connection, and I don't think you want to do that, frankly. As just a receive antenna, performance will very likely degrade above 30 Mhz or so (perhaps a little higher than that but not by much. Hams do use this antenna up to just under 30 Mhz with tuners and the like, but it's probably not very efficient much above that).
Propagation on VHF lo depends on either solar or weather conditions, particularly so during sunspot maximum. The problem is that it's been very widely reported that this is among the weakest maximum in 50-100 years. So hams hoping to chase 50 Mhz (6 meter) DX have been sorely disappointed. What this means is that the maximum usable frequency (as a broad definition, the highest frequency that will propagate between 2 points, otherwise known as MUF) has been much lower than one would expect. Put another way, if the MUF for a particular time of day is only running around 20 Mhz, if you're listening at 40 Mhz, chances are you're not going to hear much DX.
Weather conditions can play a significant role - particularly if the weather is rather violent. When I lived in a top floor condo, I had a 40 Mhz vertical dipole in my attic attached to an old Regency TS2, and right around when severe TStorms or snow were approaching, signals from Tennessee, Georgia and Florida were regular visitors.
You might profit from doing a little homework using Google or your favorite search engine on 6 meter propagation. While this is the very top of the VHF low band, the techniques and discussions are quite applicable for the rest of the band as well. There are maps out there that allow you to view the MUF in a given area. I'm sure some folks here can recommend some simple sites - the ones I have tend to be a little much for a newcomer.
A good indicator would be to listen for any VHF lo band traffic in your area. I can remember many times using an old Regency handheld and a 6 meter mag mount, listening to California during the last solar maximum on 39 Mhz (where our local State Police can be found). If you start to hear stations - particularly mobiles - that you didn't hear before, chances are that some enhancement is taking place. I would also put in 29.60 (10 meter FM simplex) and 52.525 (6 meter FM simplex). These 2 are well known ham frequencies.
Another good rule of thumb is to
loosen that squelch. Skip often 'builds' - it may start off as a weak, scratchy signal and get stronger as the event progresses.
As for an antenna - if it were me, I'd build a vertical dipole for 40 Mhz (the length of each element would be the famous 234 / F(mhz) . No need to fool around with shortening due to ground effects and so forth - we're not transmitting here). Use the techniques found in our Off Center Fed Dipole article. Make very sure that the coax is running perpendicular away from the antenna for a good bit before dropping down - this prevents the coax from interacting with the antenna.
Homebrewed Off-Center Fed Dipole - The RadioReference Wiki
HTH....Mike
