<div dir="ltr"><div><div><div><div><div><br>Well... I don't have a lot of control over the vehicle length. It's a Ford Transit Connect. I can try to heat it up some.. :)<br><br></div>Vertical separation isn't going to be a thing either. It's 73" high and my SG7900 is 62" high, topping out at 11' 4". The HF antennas are 86" so when mounted, 13' 4". Good thing they are all foldovers!<br></div>I will likely have at most a foot or two where the middle antenna can live, in terms of front to back play between support ribs.<br><br></div>Back in the day, I made an argument for intelligent power control, but got no traction. So what happens is that any time you can't make the digi the rig gets switched to "high" and there's no incentive to kick it back down to low. Basic industrial design says that you might as well not have the power control feature since it will just get left in the "high" position. Seems not too hard to have the power set to low, and if you don't hear a repeat of your packet in N attempts, then kick it to high. With additional brainpower, then knowing the range to the digi, you can choose to lower power again if approaching.. Wouldn't be fool proof, but it could be made to work. Are we still doing "wind speed = 0 means I don't have sensor or there's no wind" and "temperature = 0 means I don't have sensor or temperature is 0"? Back in 2001 I showed APRS to Dr David Arnold of BSU, and he immediately noticed that the baro sensors of various stations indicated hurricane force winds in various directions, and commented that it was probably 10 years from becoming useful for severe storm applications. :( <br><br></div>While making the drive up to a friends last weekend, an hour drive with a 4000' climb in the last 30 mins, I was remembering how I should be looking at a plug-in electric. Lots of different situations, and we all do what fits best for our own. I'd love to carpool, but my hours are unpredictable. Bike is not a thing at 18 miles one way. <br><br></div>I thought about a notch filter for 4.39 on the 7000, but I don't think I can make one that is narrow enough and small enough. <br><div><div><br><br><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Apr 27, 2017 at 5:12 AM, Ev Tupis <span dir="ltr"><<a href="mailto:w2ev@yahoo.com" target="_blank">w2ev@yahoo.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div style="font-family:courier new,courier,monaco,monospace,sans-serif;font-size:medium"><div><div>The issue you are dealing with is exactly why I strongly suggested that USA APRS move to 147.585 MHz during the "great QSY" from 145.79 MHz. Many 2 meter SSB/CW operators with tall towers and living on hills (the very infrastructure that APRS needed) would suffer from self-QRM and likely abandon APRS if it moved *closer* to their operation. That is exactly how it played out.</div><div><br></div><div>Your issue is also fundamental overload, however the real-estate you are working with is significantly less. You can't separate your antennas by 20 vertical-feet. ;-)<br></div><div><br></div><div>The safety of the radio is determined by the ability of the RXing radio's first amplification stage to absorb RF. Without knowing what the radios' ability in that regard, there is no way to quantitatively answer your question.<br></div><div><br></div><div>On the other hand, some empirical strategy can be applied, as the known quantity is the size of the vehicle and the RF outputs involved. You control both. Adjust both for best performance.<br></div><div><br></div><div>Start by separating she antennas as far as possible, however also consider testing with the antennas in different vertical planes, too (even if they are closer). To a vertically polarized antenna, vertical separation provides greater isolation than horizontal distance...however in a mobile environment, having the passenger compartment's "bump" in the way may mitigate that. <br></div><div><br></div><div>Then, reduce power output to a point where you can still communicate (this is an FCC rule anyway, of course) and see if you can live with the self-qrm that remains.</div><div><br></div><div>All of this results in a "most acceptable self-QRM" solution.<br></div><div><br></div><div>Best regards,</div><div>Ev, W2EV</div><div><br></div><div><br></div><div><br></div><div><br></div></div><div><br></div><div id="m_2941879241917744633ydpdf378d58ydp83510c74yahoo_quoted_3390734085" class="m_2941879241917744633ydpdf378d58ydp83510c74yahoo_quoted"><div><div class="h5"><div>On Thursday, April 27, 2017, 12:03:49 AM EDT, david vanhorn <<a href="mailto:kc6ete@gmail.com" target="_blank">kc6ete@gmail.com</a>> wrote:</div></div></div><div><div><div class="h5"><div id="m_2941879241917744633ydpdf378d58ydp83510c74yiv8095442293"><div dir="ltr"><div><div><div><div><div>So, I'm about ready to push the button on this. <br></div>I'll be limited by the location spots available, but I have one more question:<br><br></div>I'm intending to have the FTM-350 running APRS, and the IC-7000 running voice on 2m/440<br></div>I know I should mount those antennas as far apart as possible, but given the 50W output of each, what is the minimum separation for the safety of the radios? <br><br></div>It's almost certain to end up with the 7000 V/U on the front mount point, FTM-350 on the middle, and the 7000 HF antenna on the back. <br><br></div>I know the APRS will still punch holes in my reception on the 7000 VHF, but I'm hoping to minimize that. My main concern is not having the front ends damaged by the RF from the other radio.<br><br clear="all"><div><div><div><div><div><div><br>-- <br><div class="m_2941879241917744633ydpdf378d58ydp83510c74yiv8095442293gmail_signature"><div dir="ltr">K1FZY (WA4TPW) SK 9/29/37-4/13/15<br></div></div>
</div></div></div></div></div></div></div></div></div></div><span class="">______________________________<wbr>_________________<br>aprssig mailing list<br><a href="mailto:aprssig@tapr.org" rel="nofollow" target="_blank">aprssig@tapr.org</a><br><a href="http://www.tapr.org/mailman/listinfo/aprssig" rel="nofollow" target="_blank">http://www.tapr.org/mailman/<wbr>listinfo/aprssig</a><br></span></div></div></div></div></blockquote></div><br><br clear="all"><br>-- <br><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr">K1FZY (WA4TPW) SK 9/29/37-4/13/15<br></div></div>
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