Sunday, 21 October 2018
Yaesu marketing are in full overdrive claiming the FTDX101 is a direct sampling SDR. Sure their display is driven using direct sampling SDR technology, but anything you hear out the radio (the bit that counts?) goes through a mixer to a 9MHz IF then through a roofing filter etc etc. The whole point of direct sampling is exactly what it says on the tin "direct sampling" of the RF from the antenna not of a 9MHz IF with analogue mixing spurii! Same goes for Icom 7300 and 7610. If you want real direct sampling technology "to listen to" get a Flexradio or an Annan. It is really that simple. I hope the market can come up with guidelines on how to properly describe the glut of new architectures coming onto the market. Something like: hybrid SDR - Anything that uses a mixer as part of the receiver chain that eventually produces audio i.e. Icom/Yaesu/Kenwood/Elecraft. SDR - Anything that directly samples (at more than double the input RF) from the antenna i.e. Flexradio/Annan.
All radios when sending cw with PTT enabled (no full or semi break-in delay) have cw sidetone alone coming out of the speaker to allow the user to hear what they are sending. Flexradio have decided that this is isn't enough and have filled the gaps between the sidetone with receiver hiss. No antenna is actually connected to the receiver during this time, but the engineers at Flexradio think it sane to decode the receiver open circuit anyway. Flexradio engineers fully engage with the full and semi break-in brigade (rag-chew, DXers, occasional contester) as this category covers 99% of the user base. These modes are useless for serious contesting, let me explain why: Flexradio Full break-in (really useless): 1) CW contesting is normally done with an amp over a 48 hour period of approx 50% duty cycle tx. This kind of usage will shorten the life of the tx/rx switching mechanism dramatically for both radio and amp. 2) When running a frequency I have no need to hear between my transmissions as those heard are mostly slow or poor operators. Flexradio Semi break-in (useless): 1) A delay is used to stop the radio unkeying between each cw element and character. This saves the tx/rx switching mechanism somewhat (if set correctly), but unfortunately this delay is also added to the end of the transmission where I want to be listening for fast return callers. 2) If I need to vary my cw speed the delay must also be adjusted. Not good for multi-op contests. Let me now explain why computer PTT or manual footswitch PTT is best: External Winkey/Footswitch PTT (brilliant): 1) When sending via my computer, it knows when the end of the stored message is coming and can remove PTT immediately allowing me to hear fast return callers. 2) When sending via my paddle (external K1EL winkey), its hang-time parameter is sufficient to save the tx/rx switching mechanism. 3) The hang-time delay parameter of my winkey changes value automatically with speed. With Flexradio implementation of what to do when PTT is applied, the operator has to listen to the following for a sent "CQ": long sidetone, false hiss, short sidetone, false hiss, long sidetone, false hiss, short sidetone, false hiss, long sidetone, false hiss, long sidetone, false hiss, short sidetone, false hiss, long sidetone, false hiss, real rx hiss. You can imagine how annoying this is going to get over a 48 hour period. Sure you can dial in some flexradio delay to get rid of the false hiss but then you get the above semi break-in disadvantages. Numerous users have reported this fault to Flexradio, but they think they know better...
Monday, 19 February 2018
I'm just back from doing the above contest. Using a K1EL winkey within the Microham DigikeyerII and Win-test contest logging software. I had the following problems: 1) When setting the Microham software to provide PTT with lead (20ms, to protect hot-switching amp) and constant tail (10ms, minimum allowable setting) I discovered that Win-Test drops the PTT on spaces when sending predetermined cw messages, even though it knows it hasn't sent the complete message. To counter this without lengthening the standard PTT tail, you need to replace spaces with several ^ characters (the halfspace character with 1/2 dot duration). 2) My laptop computer (Dell D630 single processor 2.4GHz processor speed) running cw skimmer, microham router software and Win-Test caused variable cw timing, pauses, burps and stalls when too many Win-Test windows were open (such as instant rate monitor, world map, statistics and other non-essential windows). This is puzzling as the K1EL is meant to be there to offload timing from the processor precisely to get rid of these timing problems. 3) CW sending speed would range every so often between the correct speed and about double that requested, normally at the "tu GM5A" end part of the exchange. 4) The winkey was set up to have independent speed control (alt-v for Win-Test messages and speed control on Microham for hand sent morse). In most cases the two speeds were the same, even when set differently!. A few taps of the escape key would return the hand sent speed to that suggested. 5) When joining a message with hand sent morse, there was always a stall, I think you have to tap the key then start sending with the key. All in all the net performance was far short of the required performance. Everyone hated whatever was causing all these faults, determining which part of the setup is responsible is difficult. The team recon that returning to a simple serial port transistor switched PTT and CW sending method would cure most problems. I am disappointed with the Microham and K1EL keyer for making such a bad job of a simple task!
Saturday, 30 December 2017
I bought one of these antennas at the Lincoln national hamfest from Martyn Lynch. I had bought a 40m OCFD from them before which seemed to work fine, so decided to go for something a bit more expensive. At £200 this antenna isn't cheap, but I bought it for some practical reasons: 1) I wanted an antenna with low noise 2) That would add height to my scaffold pole support (so the antenna would clear my roof line) 3) Multi-band capable as I have a small plot and only one support. 4) Needed something better than my OCFD for CQWW CW contest in 2017. The antenna arrived after an unplanned 3 month wait due to EAantennas not being able to keep up with orders. During the wait I complained to Martyn Lynch who offered a 10% reduction on price, then to EAantennas directly who responded, but failed to get the antenna to me for CQWW CW (It arrived the day after the contest). During assembly I noticed multiple problems: 1) The insulator clamps that hold the elements to the mounting plate are very odd. A clamp in my mind is something with 2 separate parts, these were one solid part with bolts through them. How does this clamp the element? (poor design). 2) The bolts that go through the insulator clamps are just long enough to catch the nut on the opposite side of the mounting plate. After much hassle I ended up flattening the spring washer with pliers to enable 1 turn on adjoining nut (poor design). 3) The balun is secured to the base plate and the element ends to the balun, if the element clamps fail, the elements can rotate and the connection bolts are long enough to short to the base plate (poor design). 4) The elements are too long and heavy for the surface area of the base plate, this means the element clamps are too close together, meaning the antenna is self-detonating in ANY sort of wind. With the antenna assembled I mounted it to the end of the scaffold pole (6m long) and raised the antenna in the sky. Inside I tried the antenna on 10 and sure enough the SWR was around a 2:1 in the cw portion. Jumping to 20m, the SWR was around 1.5:1. Not too shabby! I moved to 30m and used my LDG RM600 remote tuner (directly under the antenna) to bring the antenna into resonance. I was excited to try 30m as my OCFD never allowed me to operate there. I put the linear on and decide to start low at 250w to see how it played (the instructions say maximum potential 1Kw). I made 5x 1min qsos before the SWR started to rise, I could tell straight away it was the balun as after a while to allow it to cool down, the SWR would start behaving again. Maybe the antenna was so far out of resonance on 30m that I could only run 100w there. Oh well, I moved to 40m after an hour or so to let things cool and repeated the above experiment. Unfortunately the same thing occurred. At this point I realised I had bought a pup! The balun was completely useless! Luckily I had a proper 400w 4:1 balun made by GWhip. I went out and swapped out the EAantennas balun and tried the above experiments again and this time no problems (still fine at time of writing). The only downside was that I could no longer tune 30m (2.5:1 swr best case after tuning). The weather deteriorated after a week of having the antenna up and the forecast said 25mph winds. I had my doubts, but the specs said >85mph for the antenna, so I left it up. Big mistake, in what I would call light winds, the antenna started to bend at the base plate. Unfortunately I was at work, so by the time I got home, the antenna was at a 20 degree angle from vertical. I rotated the antenna round into the wind the other way and the wind straightened it up somewhat. What a pile of junk! Totally useless! This antenna is going in the skip (minus the after market gwhip balun, its actually worth keeping as its specifications are truthful and it performs to specification unlike the Delta 7B). Do not buy the Delta 7B unless you live on the moon.
Friday, 3 November 2017
1) "my callsign" being sent by a caller...I know my callsign! 2) Unnecessary "tu" reply after my "tu" which covers the next caller....thanks for slowing my rate, agn agn?! 3) "579" rx report rather than just "599" ,does it really matter?...arg tab? space? QRX QRX! 4) "/QRP" ...never do them the favour of repeating back this stupidity...not in log more like! 4) "CFM"...thanks for this needless remark and for slowing my rate! Please note DL especially. 5) "?" covering over callers...you impatient f%^k...just wait till I repeat my call every 20-30secs! 6) "ur call?"...why did you call me if you don't know my call? Just wait till my next cq call you muppet! 7) "pse QRS"...no, you called me, you have all the time in the world to work my callsign out. Did you recognise any of these? An additional note: The reason I am going >30wpm is to role off the pile-up...in short I want to lose your Q...don't call me mid pile-up under 20wpm in this situation, just tune on... I'll get you S&P later at your speed.
Hurray! After 4 years and multiple posts/complaints from cw operators all over the world, Flexradio has finally realised that PTT doesn't work in CW mode. A fix came in v2 of SSDR software and now we can use Flexradio in CW mode (non QSK) for the first time! Flexradio seemed too wrapped up in dealing with QSK ragchew operators and only recently (when looking at contesters needs) finally realised that the customer knew best all along. The fix wasn't well advertised and I was most surprised to find it worked when I tested v2. Now when you unkey you don't have to wait for a QSK delay thus missing the prefix of any return callers. This was the last big bug I have in the basic functionality of SSDR. Now hopefully we can get a noise blanker or some noise reduction functions that work for everyone.
After all the bugs I found on the President Lincoln II for cw operation (see this blog), I was eager to try the II+ to see if President had bothered correcting any of them. Nevada had a flash sale and I decided to pick one up. I shall get straight to the point here.... 0 cw changes...I repeat 0 cw changes. What a massive disappointment. Long DAH problem when initial sent cw element is meant to be a DIT - still there Need to use RIT or split to equalise TX/RX frequencies to make any cw contacts - still the case Initial sent cw DAH frequency change due to RIT being off centre - still there Still the crap double sideband receiver mess - still the case And a new one....when you press and hold the up or down scan button on the microphone, you only hear the frequency you started the scan on. The only way to hear each frequency is to continuously tap either button leaving enough time for the audio to recover between each press. The radio sounds awful, I'm never finished fiddling with the RIT, something in the receiver chain blows big time...voices sound weak and dual tone like a dalek (I'm being kind here). I really cannot express my disappointment in this radio enough. It's not even that I bought an early version (both v3) or a Friday pup, I have two of them and both sound crap. I cannot believe anyone out there who owns an original Lincoln could like this radio. RF engineers at President should hang their heads in shame. Your peers really have showed you a clean pair of heels, the young apprentice has tried to take SMT short cuts and been distracted by DSP trickery and the result is a radio only the newbies could want to like (due to the cost). Any company who has been given free testing resource, free feedback and ignores it all and adds insult to injury by producing an update and calling it "+" as if it is an improvement, then just knocking out the same old crap deserves to go bust. I really do not like President Lincoln II (v3) or President Lincoln II+. I am embarrassed to have recently contributed to their coffers..twice!