[MRCA] [ARC5] Reading Airshow AAR
B. Smith
smithab11 at comcast.net
Sat Jun 13 18:35:12 EDT 2026
That's definitively a "109" Mark.
breck
k4che
On 6/13/2026 12:09 PM, Tim via MRCA wrote:
> Good on ya Mark ..That's a lot of work....You're showing the rest of
> us how it's done...
> BZ!
> Tim
> N6CC
>
> On Sat, Jun 13, 2026 at 8:22 AM Mark K3MSB via ARC5
> <arc5 at mailman.qth.net> wrote:
>
> Here's my attempt at a somewhat decent AAR.....
>
> image.png
>
> image.png
>
> I spent 4 days at the Mid Atlantic Air Museum's World War II
> weekend as part of a regional reenactor group. Setup was Thursday
> June 4th with the event running Friday June 5th through Sunday
> June 7th.
>
> This was my second time at Reading as part of the reenactor group,
> and the start of my second year of reenacting in general. Weather
> was hot and somewhat humid, but I had a nice breeze through the
> Comms Tent on all three days.
>
> It was great to see the B-17 “Sentimental Journey” in the skies
> over Reading, as well as the A-26 Invader “Silver Dragon”.
>
> Overall, I had a steady stream of visitors in the Comms Tent all
> three days, and did numerous demos each day.
>
> Objectives:
> Educate people on the HF / VHF radios used on Allied Aircraft in
> WW II.
> Describe the differences between the SCR-274N Command Radios and
> SCR-287 Liaison radios.
> Demonstrate how a DF unit works.
> Demonstrate a BC-611.
> Explain that during the Battle of Britain, the British not only
> had to determine the position and speed of the German aircraft,
> but also of the British aircraft in order to formulate a least
> time / least fuel intercept solution.
>
>
> Equipment used:
> SCR-274N system. Working on 40 & 75M AM. 40/80 TX, 40/80/LF
> RX. New this year were two remote tuning cables and a new Pilots
> Control box that was in better shape than my old one. Powered by
> a pair of 12V 100 AH Lifepo4 batteries in series. Dynamotors
> used for the transmitter and receivers.
>
> SCR-287 System. The BC-375 and 2 additional tuning units were
> static display only. The BC-348Q was working and has it's original
> dynamotor. Powered by a pair of 12V lawn tractor batteries in series.
>
> DF Setup consisting of a DU-1 and an ATA CBY-46145 Broadcast Band
> Navigation Receiver. Due to the lack of NDBs in the area, I did
> not attempt to use my BC-453 Beacon Band Navigation Receiver this
> year. The BC-453 was in the SCR-274N rack. The ATA receiver used
> a dynamotor. It was powered by a pair of 12V lawn tractor
> batteries in series (the same ones used for the BC-348Q). HV for
> the DU-1 was obtained from the center connector of the ATA receiver.
>
> BC-611. Working on 75M AM. Used 4 D batteries and the DC-DC
> converter that used to be made by the Italian fellow. Worked well!
>
> SCR-522 VHF system with BC-608 Pipsqueak unit – Display only.
>
> Setchell Carlson BC-1206 LF Receiver. Display only.
>
> MN-36 Loop Antenna. Display only.
>
> BC-221 Frequency Meter. Display only.
>
>
> What did I expect to happen:
> Use the HF radios to talk to others at the event;
> Use the DU-1 and associated receiver to illustrate how an aircraft
> found it's position by the DF process.
> Use the HF radios to “talk to each other” during demos.
>
> What Happened:
> I made two BC-611 to BC-611 contacts with Mark WW2RDO who was also
> at the event.
> I made one contact with Don K3OP with my SCR-274N. He was in the
> parking lot with a TS-480.
> All three contacts were on 75M AM.
>
> Demos of the DF setup, BC-611, and SCR-274N worked extremely well
> and was well received.
>
>
> What went well and why:
>
> The DF demo went well. I had the ATA receiver tuned to an AM
> broadcast station about 50 miles away. I explained how the
> operator would manually turn the DU-1 loop to find the maximum
> signal then report the bearing to the pilot (yes, I know they went
> for the null, but I didn't think that detail was relevant for my
> purposes). I explained that the DU-1 loop was normally mounted on
> the fuselage with an extension shaft to the operator's table, and
> I showed them the scales the radio operator used to determine the
> bearing to the station. I had an MN-36 Football next to the DU-1
> for static display, and I explained that there was a loop inside
> the MN-36 that was motorized and worked the same way as the manual
> DU-1.
>
> I then mentioned that our equipment tent has a Gibson Girl and
> explained what it did, how it was used, and that downed crews were
> found using the same DF process from land bases or flying boats.
> I explained these were examples of “Passive DF”. I then
> explained how the SCR-247N could be used by a lost pilot to get a
> bearing to a known ground station by pushing the transmit button
> on the Transmitter Control Box in order for a ground station to
> give a pilot a bearing to the station.
>
> I explained the function of the Command sets (short range air to
> ground / air to air) and contrasted that to the function of the
> Liaison radios (long distance). I showed them the inside of a
> command receiver as many of the younger people had never seen a
> vacuum tube. I explained what each box did and how they could be
> located in different parts of the airplane, and what the pilot's
> receiver and transmitter control boxes did.
>
> Demos were varied.
> Transmit on the 274N and listen to the signal on the 274N receiver
> or the BC-348Q.
> Transmit on the BC-611 and listen to the signal on the 274N
> receiver or the BC-348Q.
> Feedback considerations aside, these demos worked fine and were
> well received by the visitors.
>
> The SCR-247N was on 3885. Last year, my antenna was a 45 foot
> wire that exited the CommsTent, went over the top and down the
> other side, then ran parallel to ground around the perimeter of
> the tent at a height of just over 6 feet. This year, I used a
> Hustler 75M Mobile antenna attached to one of my wife's biggest
> baking pan (yes, with prior approval....you don't get to be
> married for 44 years without asking about something like this
> first....). The assembly was hidden behind a canvas partition in
> another part of the tent. A counterpoise was used. Matching was
> accomplished by my custom box of a 4:1 UNUN and series matching
> capacitor and MFJ Tuner. Matching was not a problem
>
> I explained the use of the BC-221 Frequency Meter and explained
> how all the various radios were netted to the mission frequencies
> before a mission.
>
> I explained the use of the SCR-522 and how it was used alongside
> the SCR-274N and SCR-287 radios. I had the BC-608 “Pipsqueak”
> unit running and explained that this was used to aid the British
> in determining the position of their own aircraft. I explained
> that every minute for 14 seconds, the Pipsqueak would cause the
> SCR-522 to send out a signal, and the ground stations would DF
> (triangulate) on the signals to get an accurate position of the
> Spitfires, Hurricanes, etc. That position, combined with known
> winds at altitude and the specific performance of the various
> aircraft types, the best intercept solution to intercept the
> German aircraft would be determined. Explained this was pre IFF.
> Most visitors had no idea the British had to do this. My goal was
> to get the visitors to understand the complexity of how the
> British got their planes to intercept the Germans; it was a LOT
> more complicated than “Go East young man”....... and the
> computations were done without computers!
>
> To tune and net the SCR-274N each morning, I had an ICOM
> transceiver in a plastic container under a canvas tarp on the
> bottom shelf of my big table. Day to day tuning of the antenna
> was minimal, and surprisingly the radios held frequency very well
> day to day. Netting the SCR-247N TX to 3885 was quick using the
> ICOMs band-scope.
>
> What can be improved and how?
>
> Antenna for the SCR-274N. The mobile whip worked OK, but others
> not on the field were unable to hear me at the appointed times.
> And, since I was making short transmissions during my demos (with
> proper FCC ID.....) that may be a good thing. I need to get a
> wire antenna vertically up through the top of the tent then
> horizontally to another tent. There are non-technical reasons why
> this is a challenge, but I will try again next time. I enjoy
> POTA (Parks on the Air) and I use a 55 foot wire to a 9:1 balun
> for 40M. No counterpoise, and it works very well. I'm doing to
> try that on 80M as well. Try as I might, I've never gotten a 274N
> transmitter to work directly to a wire regardless of using a
> counterpoise or not. This is why I go from the 274N via a 4:1
> UNUN and series matching capacitor into the MFJ tuner; I can get
> 50 ohms unbalanced into the tuner and let the MFJ handle matching
> whatever I put on the other end. The visitors never see this stuff.
>
> Build a DC-DC converter for the BC-221 so I can actually demo it.
> It currently runs off of 110 VAC and that doesn't do me any good
> in the field.
>
> Get dud tubes for the BC-375 to display them.
>
> Have a code practice oscillator available for the young kids to
> play with.
>
> My mic for the SCR-274N went belly up on Sunday afternoon. Bring
> a second mic.
>
> Conclusion / comments
>
> Being able to demo the SCR-274N and BC-611 at will for people was
> a huge success. Most people assumed that radios were just
> replicas until I turned on the SCR-274N and they heard the
> dynamotors spin up. “You mean this stuff works?”..... “Yup,
> let me show you”....
>
> My setup was well received by young people. I had kids turn the
> DF loop if they wanted to for a “hands on” experience.
>
> A father and daughter came into the tent. He said his father
> (her grandfather) was a radio operator on a B-17 during the war.
> I told them the radios I had were the ones he would have used.
> After I gave them a demo, I noted some tears starting to form in
> the granddaughters eyes. Encounters like this make all the time
> and aggravation of getting these radios restored and working in
> the field worth it. We talked for quite a few minutes afterwards.
>
> A young girl, maybe a teenager, came in and I gave her a demo.
> She then asked me “that's good, but how do you address the battery
> issue on the BC-611? They can't be good after so many years”. I
> said that was a great observation and told her about the DC-DC
> converter inside the unit. We talked a bit more about restoration
> and she then said she enjoys restoring first generation computers
> and runs into some of the same kinds of problems I run into. OK,
> she's not restoring radios, but she is restoring! That's a start!
>
> Saturday night around sunset we had weather warnings about a
> severe squall line that was approaching. Heavy rain and strong
> winds, but the line was pretty narrow. Each night I cover my
> radios with a vinyl tarp, even though the radios are in a zipped
> canvass tent. The tent is old and leaks a bit..... So, I got
> the tarp over the radios and we secured the tent, double checked
> the tie downs etc. The squall line hit and the winds were
> strong. All of sudden people were yelling as one of the main
> sleeping tents that housed about 10 cots and people's belongings
> went airborne. Apparently wind got under the tent. So, it was
> all hands on deck to get the tent back over people's belongings
> and we sat on the tent getting drenched to the skin for several
> minutes. We spent about an hour afterwards helping to get the
> tent back up.... all was completely soaked.
>
> Afterwards I realized that in the Comms tent, under the vinyl
> tarp, in a tight plastic box, in a small canvas bag.... was my
> poncho..... nice and dry.....
>
> 73 Mark K3MSB
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