--- In [email protected], "Willis M. Hagler" <[EMAIL PROTECTED]> wrote: > > Hi All, > > Does anybody have experience running the DB 404/408/420 type antennas > down around 440.000mhz transmit?
High Mark, First, you didn't say if your planning on ordering one built "on" your 440 freq.,or trying to use a used existing one from some commercial freq. If your ordering a "NEW" one, it'll work great...right to spec..Know of 2 clubs that did that. If your going the "used" route... I've got a friend who is using a 408 now on his repeater whose output is around 442.500. The antenna works great. But there are some caveats... First off you will definitely loose some of the gain from the original "rated specs". About 1.5 - 2 Dbd. is what I'd expect...Maybe a little worse depending on where the antenna was originally "cut for"... For example, If the antenna was originally built for say a 454.xxx freq (center freq) the loss would be less at 442.xxx than one that had been built for 467.xxx. The antenna typically has a 20Mhz. bandwidth, +/- 10Mhz each side of center freq so you can see that one cut for the upper 460-ish range would be a little worse than the 450-ish freq. The next thing that would change would be the "downtilt" rating. This will increase the more "out-of band" (in your case lower in freq.) you go, which may be a good thing depending on your particular situation/use/mounting structure / height /etc. If your looking for maximum distance, this may be an issue, but if your looking to,or have a need to "fill-in" lower areas this would help by bringing the "lobes" down more than original pattern... > > I like the DB's but unsure how bad the 450mhz matches when trying to > use it down at 440.000mhz. Thats easy,..Put a wattmeter on it and check. The 2 I've helped friends with have typically had less than 250mw reflected with 40-50 watts forward. They have been very happy with the performance... Hope this adds some insight to your "search for info"... Carl KA9GPX One thing I can attest to is you've come to the right place to ask about antenna info.....Just don't mention the word "Scrap" around here when it comes to Aluminum antennas...;-)
