May 2020 – Month 3 of the Pandemic – Radio Activity

•May 24, 2020 • Leave a Comment

It’s May in the year of the COVID 19 Pandemic.  It’s been a while since my last post here and I’m significantly behind, despite being holed up and sheltering in place. A strange time of Zoom virtual meetings online like our EARC club meetings, increased ham net activity – no brainer that one.

Radioactivity

Continue to build matchbox antennas but the field day rush is off – field day 2020 is going to be a ‘field day alone’ or ‘field day at home’ event.

I revisited my 2M moxon today (5/24/2020) and checked it out using Winlink Express and VARA-FM. At 145.07 mhz measured the front back receive signal difference of 1-2 S units (6-12 dB) and SN ratios of between 5 and 9 dB – at least it is not omnidirectional.

Most significantly I’ve upgraded my digital software suite for WSJT-X. I get much better situational awareness than before. In addition, it’s much easier now to set goals and go after WAS, for example. The work factor is much less and helps interest overcome apathy. We’ll see.

| -- Ham Radio Software - 
|       |-- WSJT-X  2.2.0 -rc1  May 2020
|       |-- JT-Alert 2.16.5
|       |-- DxLab Launcher
|       |-- DxLab Keeper 156.4.9
|       |-- DxLab View Map 4.6.4
|       |-- pskreporter
|       |-- QRZ.com

JT-Alert allows a qso callsign  lookup on QRZ - nice to have, and provides a significant "w/b" worked before

20 meter opening to Europe on FT8

•May 10, 2019 • Leave a Comment

For the first time I caught a 20m opening with FT8 the last couple of nights and worked stations in the UK, Finland, and France.  9may2109z ~0600-0700

8 may,  the sunspot number was 25.   The sunspots went from 11 on may 4 to 25 by the 8 may( today on 10may N = 25).  I wonder.   Probably unrelated, earlier in the day 8 may the 0900W 40m net was a bust on 40m 80m and 60m – very poor conditions.

euro8may19ft8.png

Working conditions: 20m ft8/wsjt-x, 84′ doublet, linear amplifier – 30/400 W (-13 db), 4:1 #61 balun temp : 43°C

Other:  heard only 25% or fewer stations than could hear me.  reception is 75% of the  problem!  Power probably needed and I used it to make contacts: 400w -13db: calc- 200 -16 db, 100w -19 db.

80 Meter Dipole upgrade

•February 21, 2019 • Leave a Comment

19 Feb 2019.  upgraded the 40m dipole to 80m by adding two 30’4″ lengths of #30ga stranded wire.  It took a couple of stages but the job is done.

SWR at rig end from the 4:1 balun
80 3.88  4.5
60 5.35 11.1
40 7.04  24
40 7.18  24
30 10.1  5.3
20 14.0  6.3
20 14.2  7.0
17 18.1  1.6
15 21.2  4.0
12 24.9  4.9
10 28.2  2.7

SWR at rig end from the twinlead before balun
80 3.88  28
60 5.35  2.4
40 7.04  > 30
40 7.18  > 30
30 10.1  18
20 14.0  2
20 14.2  2
17 18.1  3.5
15 21.2  3.4
12 24.9  9.3
10 28.2  2.7

With the 4:1 Balun
The Kenwood TS590SG can tune  80, 30, 17, 15, 12, and 10  meter bands.
The MFJ-901B tuner is needed for 60, 40, and 20 meters.

Materials: 30awg wire – white teflon coated  for the west leg to blend with the building, black silicone (200 F) for the E which is more invisible in the air.  U shape, first 30′ on both sides then just folded/dropped to fit in.

Construction: original PC board T support with two hole strain relief – this design has held up well since the beginning.  The original 30 ga single copper conductor wire became brittle over time and had to be replaced.  The stranded should be a bit stronger and more flexible.  I made a splice board with copper clad board – two hole strain relief design, 1/2″ by 2.5″ copper sheet jumper taped in place on the west side, antenna wire  soldered to the copper plate.  The jumper is soldered on the E … originally the idea was to use the copper sheet as a switch conductor to easily remove the 80m stub – this is impractical for permanent installation.

Performance : so far so good, definitely louder on 80m, suspect 40m is compromised.  The balun observed to heat up to 140F after operating for a while long 100w FT8, runs cooler on other bands so need to be careful on 40m.

Is the end fed now better on 40m ?   2/21/19  –  it works pretty well and may be outperforming the dipole … several factors including EF wire orientation (NS (ef) vs EW {dipole} )  of highest current segments and height may affect this too!

135 foot Length
The ARRL Antenna book lists a 135′ doublet recommended length … this length may work better than 120 with much lower 80 and 40m SWR before the balun (the 1:1 , i.e. no transform, swr)

135′ dipole SWR at rig end from the 4:1 balun 
 λ     f 
80  3.5       5          4
80  3.88     4          5
60  5.35   14          12
40  7.04   25        24
40  7.18   25        24
30  10.1    2           1.6
20  14.0    9           8
20  14. 2   9           9
17  18.1    5           5
15  21.2    3           3.4
12  24.9    4           5.4
10  28.2    3           2

 

Yaesu MH-31 Microphone Failure/Fix

•February 17, 2019 • Leave a Comment

Problem: No transmit audio on the FT-857D tranceiver.  FM/AM/CW produced a carrier.

mh31a.PNG       mh31cart.PNG

RFO: Dynamic microphone cartridge failure.

Detecting failure.  Besides no transmit audio, measurement of the resistance between the two cartridge leads enabled diagnosis.  The cartridge should have with a normal resistance of between 200 to 600 ohms.  Instead the faulty cartridge presented an open (infinite) resistance as measured by a DVM

.

mh31schema.PNG

This was a bad dynamic mic cartridge that checked out with infinite R instead of 200 – 600 R. Given the mic was dead, seemed like a no-brainer to do the electret mic conversion since I had the parts.  Used the electret mic cartidge that came with the uBITX and followed m0ukd’s schematic. The utube is excellent with a very similar solution. QSO on 40m confirmed decent sound on the FT-857D with the new refurbished microphone.

Performed this mod with parts on hand , an electret mic cartridge from the uBITX project and a couple of caps on hand (47nf and 1 nf).

It’s important that there be capacitors in the signal path to block the +5v dc voltage.  I took some pains to insure there were no shorts since 5v would be bad news for a mic pre-amp or other circuitry downstream that is not expecting it.

yaesu-mh-31-electret-condenser-mic-modification.jpg

The microphone now works and reportedly sounds good.

 

 

TS-590SG Reduced transmit power, Reboots. Known Problem. Easy Fix.

•February 17, 2019 • Leave a Comment

20190216  Incident – TS590SG rebooted once while transmitting.   Later under testing into a dummy load, power was limited around 50 watts in CW mode, sometimes more, sometimes less.  The reboot occurred once or twice.  The lack of power affected all bands.

Reason for failure – the 25amp fuse holders and other connectors on the power cable for the TS590 oxidize over time and can cause significant power loss over time.  When the total current carrying capacity of the power cord assembly is reduced due to oxidation and gradual loss of the necessary gas tight metal to metal contact, the rig reduces power output or may reboot.

Recovery Actions Needed –  remove power cable, inspect, wipe all connectors clean, pull out, clean fuse contacts, or simply reseat the fuses.  Inspect Johnson power pole connectors and insure all connectors are seated fully.  When I inspected the fuse blades, they looked shiny and clean, but the reseat worked.  The power pole connectors are known to be subject to oxidation and losses.

Result of maintenance actions:  Restoration of normal operation.

Other – the power limiting and reboot behavior made me wonder if  a serious electronic failure, e.g. of the final mosfet transistor amplifier, occurred.  Other accounts on the web may likewise be misleading, if only because fragments of information can be  misleading.

The  problems caused by power loss in the power supply cable are not widely advertised but known to TS590 owners and amply documented online if you know where to look – but misleading information is also present.  See: https://groups.io/g/TS-590/s  or on QRZ.  Before too long I was in contact with two hams in particular with direct experience with the problem. CE3DNP and W2JDB helped me zero in on the problem. This has been characterized as a “classic” TS590SG fuse problem.  Thanks guys – saved me a lot of time and effort!

 

 

Low noise event – 2Jan2018 …

•January 3, 2019 • Leave a Comment

1/2/2018 – on or about 2 jan 2019, I noticed that  the 40 meter noise floor  dropped from S9+5 to S3 (no preamp).

Noise canceling is no longer necessary.

The source of the noise is a mystery but seemed to be related to power, maybe a noisy always on device.  Hoping for the best.

 

FLDIGI CW Split Operation

•October 25, 2018 • Leave a Comment

FLDIGI CW OPERATION – SPLIT OPERATIONS
oct 2018
Objective:
Use FLDIGI for CW and how to use SPLIT in contests and for DX stations.

FLRIG

ts2.pngfigures.PNG

split.PNG

I can’t hear call signs at 30 wpm.  I could hear my call sign at 30wpm,  I could do limited contest and dxPedition cw without fldigi.  Until that day …