Thursday, March 31, 2011

More ATS-4 Contacts

ATS-4 CQing
After packing up the Timewave again I took the ATS-4 off the shelf and hooked it up.  Some of the 2M Chatter mentioned that 17 was open....hmmm maybe I should have built it for 17M anyway I called on 15M for a while with no takers so I moved down to 20 and worked an actual QRP station, KE4I in AL.  He was running 5 watts to a G5RV and was solid copy to me.  I was only Q4 with the barely 2Watts from the KD1JV rig.  The Beacon mode on the keyer works well and I was reading emails and typing on the blog while it was calling CQ for me.

After the contact I decided to try the rig on a 'real' power supply rather than the Heathkit IP-18 that is current regulated and 'safe' for building projects.  I hooked up a 30amp dc supply and turned the Voltage up to 6 volts and turned the ATS-4 back on.  It was already putting out more power than it was at 12V on the little supple.  I turned it up to 12V while the rig was in the beacon mode and it looked like it was hitting 5.5 watts so I turned it down to about 11V and it still seems to be hitting 3 Watts.  So it seems my low output was just not enough power supply.

Went down a few KHz and called some more and worked KD0V in MN also QRP then heard and worked OK1KW  near 14.058.550.  Milan says he was running 100W to a dipole with his Kenwood TS-940S.  This I believe is 9 QSO's on the ATS-4 from home using the R7 Vertical.

eMail QSL received - Thanks Milan

"To: K3PG

Hi Paul,

Thanks for the email and QRP connection. Your signals are quite good, but I was disturbed by the local station.
Thanks so much and wish you much success with your equipment on the HAM bands. BCNU.

73 and Best Regards from Prague
Milan, OK1KW"

Timewave DSP-9

Took the old Timewave DSP-9 out to look at again.
DSP-9 Top

The Audio output on this is a 'chipamp'  TDA2003 and when it went bad I ordered a TDA2006 because it is a pin equivalent but it did not work so I put it aside.  I looked at the data sheets for the two chip amps and it although they are 'pin' equivalent there are major differences in the circuit that the chips want to see according to the sample circuits provided by the mfg.  By changing some of the values I could tell the chip would come to life but sometimes it was oscillating and it would only run for a few seconds before overheating and shutting down.  Now I notice that DigiKey does have some of the older TDA2003 in stock and I think I will try to get the original replacement before attempting to change the circuit to get the newer TDA2006 to work.

Sunday, March 27, 2011

Timonium Hamfest

Thanks to local ham KA3DCO, who rode a couple of us over in his mini van.  K3JOI and KB3KXK.  Picked up a few goodies, some bits of speaker wire for the hifi stuff.  A piece of 300 ohm twinlead for another FM tuner antenna and a couple of more caps for the ST-120.  Here are a couple of pix.


Funky Finger Lights!


N4TCM shows his HF Pack set the radio is a Harris PRC-138 that was MOD (UK) surplus and used in Kosovo for logistical support. 

Want some Rocks?

Big Screwdriver

Dynaco ST-120

Put a few new caps in the ST-120 yesterday.

One new Cap in Place one amp board loose

Couple of more new caps

I installed some new caps on each Amp board and  a two new filters and two new output Caps.  The output caps were zip tied to the old ones to perserve the coils.  

Trying the amp it is not as quiet as the ST-80 so I will change a few more of the caps.  The output with no signal is reading about 300 mv vs. the 15mv on the ST-80.  Some of the other filters were not changed.  Two of them looked to be changed before and there are a couple of others on the P/S board so this will be reworked again.

update Mar 29
Picked up some of the caps at Timonium and replaced a few more of the old electrolytics and there was still no change in the 300mv DC offset however the AC signal dropped a bit.  I have not listened to it again yet.

Thursday, March 24, 2011

Dynaco ST-80 Test Listen

Got the rehabbed ST-80 online today after replacing all the electrolytic caps with modern replacements from Digi Key.  It sounds great.  I listend to some classical for a while then some progressive rock on the Yamaha T-1 tuner and C-50 preamp.  I can turn the vol up all the way and hear NO noise with no input now.  Next will try the same rehab on the ST-120 that also needs new caps.  The total cost was quite reasonable.

I removed the two caps on the right side and zip tied the new ones to the mounts.  I left the two caps on the left in place as coil forms and zip tied the new caps to the old ones.  The two circuit boards were removed and the electrolytics on each were also replaced.

Here is some info from the unofficial Dynaco site.

The Dynaco Stereo 80 is an all silicon transistor basic power amplifier for use with separate preamplifiers such as the Dynaco PAT-4 or PAT-5, or for use with tape recorders or tuners such as the FM-5 or AF-6, which have their own volume controls. The Stereo 80 contains two 40 watt amplifiers on one chassis with a common power supply.
The components of the Stereo 80 are of the highest quality to protect against failure, both now and for many years in the future. All parts are used conservatively with close tolerances to assure continued proper operation, and etched circuit modules have been pretested under actual use conditions to ensure that every unit, after assembly, will meet the specifications normally associated only with laboratory prototypes.
The specifications of the Stereo 80 speak for themselves. The distortion and noise, up to levels well beyond those required to drive any conventional amplifier, are comparable to the finest tube designs while the high power distortion remains inaudible. Specifications do not reveal all the facets of superior audio performance, however. In use with varying program material, the Stereo 80 achieves its design goals of sonic ease and naturalness always sought but rarely achieved in solid state designs. There is remarkable clarity and an impression of direct contact with the original without the extra brightness or stridency which, unfortunately, is sometimes attributed to high fidelity sound, but rather there is an impression of limitless range and effortless handling of the highest power peaks.
Rated Power Output: 30 watts average continuous power per channel into 8 ohms, 20-20,000 Hz at less than 0.5% total harmonic distortion. Distortion reduces at lower power levels.
Power at Clipping, Single Channel, 1000 Hz, less than 1% distortion: 50 watts @ 8 ohms, 36 watts @ 4 ohms, 26 watts @ 16 ohms.
Intermodulation Distortion: Less than 0.5% at any power level up to 40 watts rms per channel into 8 ohms with any combination of test frequencies. Distortion reduces at lower power levels.
Half-Power Bandwidth: 20 watts per channel at less than 0.5% total harmonic distortion from 8 Hz to 50 KHz into 8 ohms.
Frequency Response: ±0.5 dB, 10 Hz to 50 KHz @ 1 watt into 8 ohms.
Noise: More than 90 dB below 40 watts output, full spectrum.
Channel Separation: Greater than 60 dB from 20 Hz to 20 KHz.
Input: 100,000 ohm load; 1.3 volts for 40 watts into 8 ohms.
Semiconductor Complement: 12 transistors; 10 diodes.
Size: 14" by 8" by 4" high.
Shipping Weight: 13 lbs.
Maximum Power Consumption: 35 watts quiescent; 250 watts maximum; 50/60 Hz, 100, 120, 220, or 240 VAC.
Designed by:
Ed Laurent
Year Introduced:
$149.00 kit
$224.00 assembled
A pared-down version of the Stereo 120, with 40 watts per channel, and an unregulated power supply.

Monday, March 14, 2011

SuperCap as Memory Back Up

Here is the supercap that was removed from a 80's vintage Yamaha T-500. It is used as a memory backup battery and was replaced with DigiKey P/N 604-1000-ND. Mfg P/N DB-5R5D473T. Desc Cap Double Layer .047F 5.5V RAD. Fit was perfect and old unit now has memory back up again.

Lunch at Mt. Vernon

Mt. Vernon

Took a trip to Mt. Vernon for lunch with daughter and wife. Had not been there for 25 years. It was a great almost spring day in March.

Thursday, March 10, 2011

Drake R-4b Bias Filter R&R

Receiver would not fully mute, S-Meter would not go past S-9 when turning RF Gain Counter Clockwise. TP2 Voltages were not correct. Bias Voltage was good when circuit was 'unhooked' from the P/S board. Cap tested leaky compared to new one on the old Heathkit C-3 Cap checker. The new filter Cap from AES is a Sprauge Atom 10uf @ 500v which was a close as I could find to the original from Digi Key or AES at order time. The fit is a 'B' fit and required slight enlargement of the holes on the board which I did with the point of an exacto knife in just a min or two. Clearance is 'OK' if you fit it in close to the board. I added some heat shrink but it is probably not needed. After fitting the new Cap the AVC voltages all aligned up as per section 6.4.9 of the manual.

Pix of original Cap CDE 'Beaver' 8mfd @150V

Monday, March 7, 2011


Had a weekend commitment and only got on for the last 3 hours or so of this one.  Highlights were working JA and Alaska on 15 and even some SA on 10 coming in strong late in the PM.  It has been years since I have heard 10 this open!  So not much score but it was good to get on for a bit.  N1MM is nice it makes SSB closer to CW or RTTY with the button pushing.

 Band    QSOs    Pts  Cty
     7       6      18    5
    14      38     114   32
    21      31      93   16
    28       7      21    3
 Total      82     246   56
Score: 13,776

Wednesday, March 2, 2011

QA RACES visit to MEMA

The Queen Anne's RACES group took our second field trip to MEMA and had the opportunity act as net control for the monthly COMMEX.

K3PG at the Central Region Net Position

Other photos are at RACES trip to MEMA on Webshots