[MRCA] Fwd: SCR-274N with B-24 Antenna and H-Town results

Tue Jun 3 11:42:32 EDT 2025

Sent from my iPhone

Begin forwarded message:

> From: Christopher Bowne <aj1g at sbcglobal.net>
> Date: June 3, 2025 at 11:13:29 EDT
> To: Ray Fantini <RAFANTINI at salisbury.edu>
> Subject: Re: [MRCA] SCR-274N with B-24 Antenna and H-Town results
> 
> Another possibility for a vehicle mounted vertical mobile antenna install that’s very effective for me is to use a very tall say 20 foot vertical radiator as the vehicle antenna when parked.  I have one made
> from a 2 section telescoping swimming pool skimmer pole made of ribbed aluminum that makes a nominal 16 foot radiator, I add a 4
> foot Hamstick stinger and it’s mounting collar to
> alllow for adjusting the total length up to 20 feet.  Mount it into a short  PVC pipe mast step bolted inside the left rear corner of the Tacoma bed.  On 80 meters I resonate and match it into my IC7100 with a 5 Mc Command Set roller inductor between the bottom of the amtenna and the feed line center conductor and a 1000 pf shunt cap across the feed line at the transmitter side of the roller inductor.  Can get a near perfect match anywhere in the band with the roller inductor.  I’m
> actually using a complete 5
> Mc command set in a black plastic tool box, with the roller inductor for the time being disconnected from the rest of the transmitter and a pair of leads to it run to the antenna and feed point at the the antenna base. The two sections of the skimmer pole do not come in contact electrically as made, I use hose clamps and a ground bonding type braided strap or even just a single wire to connect them electrically, same thing for the Hamstick stinger collar.  Just use a Dremel abrasive wheel to scuff the blue anodized finish down to bare metal off the pole sections for where the hose clamps will contact them.
> 
> Here’s a pix of it, I call it the DX Skimmer:
> 
>  
> Sent from my iPhone
> 
>>> On Jun 3, 2025, at 10:40, Christopher Bowne <aj1g at sbcglobal.net> wrote:
>>> 
>> I think the best situation for you considering the environment would be to use either a quarter wave wire working against the body of your vehicle as a counterpoise or a mobile antenna on the vehicle.  If you want to put your setup in the tent put the tent next to the vehicle and run a coax feedline from the setup to the vehicle mobile antenna feedline.  
>> 
>> Using a cake pan as a counterpoise on 80 meters as a counterpoise may “work” in that you can load into it but it will be a very poor radiator.  OTOh, a good mobile setup at a good location can literally work worldwide on 80.  I regularly work to Japan and Australia both short and long path on 75 meter SSB from my mobile with 100 watts from seaside locations here it CT and RI, sometimes with just a Hamstick.
>> 
>> 73 de Chris AJ1G
>> Stonington CT
>> Sent from my iPhone
>> 
>>>> On Jun 3, 2025, at 10:11, Ray Fantini via MRCA <mrca at mailman.qth.net> wrote:
>>>> 
>>> 
>>> Where or what are you setting up for? I do a couple field events now and then, just finished doing Hagerstown MVPA show where I worked RTTY Net on 7087 and MMRCG Net on 7296 along with trying to get into 18.1575 Net that afternoon but was too crowded. That’s typically what I do when I have the Mutt out and about.
>>> I have found that best antenna is a inverted V being you don’t have to deal with a ground or radials or any of that stuff but at H-Town had to set up on the ramp with no ground in sight and this year with the threat of weather decided to drop the idea of a mast and V in favor of the vertical on the mutt. Using just the fourteen foot vertical twenty meters and above work great. Can work one to two thousand miles out on seventeen easy, nothing local but big coverage on high frequencies, just the antenna and the mutt. No counterpoise or wires or anything like that. The chassis of the mutt is close enough so you don’t need anything else on high frequencies.
>>> Forty meters with the vertical is ok, not as good as a inverted V but it will work. The GRC-106 loads and operates at full power without issues. This year because I had to use the whip I decided to try a counterpoise or two. My friend Breck told me that in order for a radial to be effective it had to be some multipole of a wavelength, not the fourteen foot of the antenna. So I built up some long runners to use as radials. During the morning nets I set up away from the normal operating location a couple hundred feet away from an old cargo jet and ran the radials out. Operating on forty meters both voice and teletype disconnected and connected the radials and noticed no difference in the receive signal. My thoughts was at the end of the day the radials and counterpoise or what ever you wanted to call them make no difference. Least that I can tell on forty meters and that’s whit running a bucket full of power. Kind of the same results on sixty meters. Long time ago got into an argument about efficiencies of antennas and if a properly tuned vertical can preform as well as a properly cut inverted V and my own opinion is that a inverted V will outperform a vertical all the time on forty and below. Exact opposite above twenty meters.
>>> Eighty meters  is another animal, The 106 gets squirrely on the vertical using a ground rod into the dirt for a counterpose  but I find that eighty meters is the one band I almost never use in the field except for local comms.
>>> So most of my work on eighty tends to be back pack or smaller radios like the BC-654 that I ran for NCS at Hamvention this year, but when you are just working other radios within relative line of sight how much power or antenna do you need? Eighty works great for local 3885 stuff with BC-611 and other sets but just don’t see it being a good band for field opps unless you are going to do a proper size antenna and the like.
>>> Least that’s been my experience with doing field opps, maybe the first question is just what are your intentions and goals for the event? Maybe some events are better served trying a scheduled voice backpack operation then just trying to bang out CW contacts?  At events I have done people always like watching voice QSO and they don’t need to have CW skills.
>>> Attached is a couple pictures from H-Town this last weekend. Thinking the next event will be from Gettysburg in July and the American Heritage Military museum and am anticipating opps on 18.1575, 7.296, 7.087 and 5.357 but only low power local stuff on 51.0 and 3.885
>>>  
>>> Ray F/KA3EKH
>>>  
>>> From: mrca-bounces at mailman.qth.net <mrca-bounces at mailman.qth.net> On Behalf Of Mark K3MSB
>>> Sent: Tuesday, June 3, 2025 8:59 AM
>>> To: Christopher Bowne <aj1g at sbcglobal.net>
>>> Cc: mrca at mailman.qth.net
>>> Subject: Re: [MRCA] Fwd: SCR-274N with B-24 Antenna
>>>  
>>>  
>>> Grounds wires / long cointerpoises cannot be used due to tripping hazards for pedestrian foot traffic at the event.
>>>  
>>> I thought a ground rod would suffice, but apparently not.
>>>  
>>> Depending upon where I will be setting up in the tent, I can try and run a wire around the tent perimeter.
>>> I'm not sure I can do that;  it depends.
>>>  
>>> That's one of the challenges I'm facing.  I will be in a congested area with high foot traffic.  Antenna space is at a premium.
>>>  
>>> I originally wanted to put up a CFZ or Invented VEE with the ends going to other tents, but ran into issues with that.
>>> No ground radials needed for those.
>>> My next choice was the 45 foot wire and ground rod -- hoping I can run the end of the wire down the tent exterior etc.
>>>  
>>> Last choice -- backup plan.... is my 80M Shark Mobile Antenna on a cake pan in the corner with a counterpoise....  that does work.
>>>  
>>> Mark K3MSB
>>>  
>>> <IMG_2450.JPG>
>>> <IMG_2451.JPG>
>>> ______________________________________________________________
>>> MRCA mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/mrca
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:MRCA at mailman.qth.net
>>> 
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/mrca/attachments/20250603/9921e5aa/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image1.jpeg
Type: image/jpeg
Size: 122382 bytes
Desc: not available
URL: <http://mailman.qth.net/pipermail/mrca/attachments/20250603/9921e5aa/attachment-0001.jpeg>