I would strongly suggest clip-on ferrites on your A/V receiver's line cord, and the speaker wires.  The speaker wires can act as antennas, and pick up any stray RF.  I had this happen once while using an attic dipole a number of years ago, and was running 100W.  It took out the audio amp IC in our Sony TV.  Once I installed the ferrites on the AC line and the external speaker wires, the problem went away.

The G5RV may be your source of trouble (more specifically, the feedline), as there may be some common-mode currents present on the feeders.  G5RVs can be tricky when RFI problems occur.

73
Don W9CW

Well, in the case of the ACOM 1000 and the 1010, there is only one tube - no tubes to match.  The statement in the manual regarding tube replacement, e.g. sending it back to an authorized ACOM dealer, is based upon EU liability laws, not applicable here in the USA.  If the final tube needs replacement, I am sure any technically-inclined ham could do so - with the technical assistance of Array Solutions if necessary.  No truth whatsoever that you would have to send the tube or the amp back to ACOM, or an authorized dealer.  Array Solutions has all of the technical info on tube replacement and can easily "walk you through" the tube replacement scenario if necessary.  Using the amp properly, the GU74B should last a very long time.

Thanks Mike.  BTW... I enjoyed our dinner together with Molly Hardman at Chili's at the 2010 Huntsville show, and the unscheduled stop at Walgreens on the way back to the hotel to pick up some Aleve . This, of course, was prior to my retirement from CQ at the end of that year. 

Yes, the ACOM line look like a nice amps, and well engineered with super build quality and well-protected.  Re. solid-state amps and VSWR protection, especially as to its use with an antenna tuner... it appears the Elecraft KPA500 is well-protected against most loads, and other "oops" moments.

I'm considering a new 500 to 1kW amp, and among the tube amps, I'm looking at the ACOM 1000, 1010, or 1011 (listed in descending order of price).  The 1000 and 1010 use a single 4CX800A/GU74B, whereas the 1011 uses a pair of 4CX250Bs.  The 1000 uses a larger transformer than the 1010, has a more rugged build (higher quality components) than either the lesser 1010 and 1011, supports full QSK, and covers 160-6m - whereas the 1010 and 1011 are 160-10m only.

Although the 4XC800A/GU74B has not been discontinued by Svetlana, their production runs are sporadic, and it is becoming more expensive (currently around $300 NOS), as are all tubes of course.  On the the hand, the 4CX250B remains rather plentiful, and certainly less expensive.

What's the general consensus on ACOM's lower-priced (relatively speaking of course) amps, and their long-term reliability.  The amps are sold, and backed, by Array Solutions here in the USA - a very fine and reputable company which offers excellent customer service.

The amp for this application would be used primarily on SSB, as I have another full QSK amp I use on CW.  Although it never hurts to have another full QSK capable amp in the shack...  the price differential between the low-end 1011 and the 1000 is $1,000.

I am also considering a couple of solid-state amps in the 500 to 1kW range.

Any thoughts would be appreciated...

Tnx
Don W9CW

Gedas,

I have a SB-313 that I built in the fall of 1974, and it's still looks new, and works fine after almost 40 years!  My SB-313's sensitivity was always fine on 25m, and the overall sensitivity was excellent.  The only problem I've had with the SB-313 was the LMO stops locked up after having been in storage for a number of years.  I had to remove the front panel, and lubricate the stops on the front of the LMO shaft.  Other than that, it's been trouble free since the build.

73
Don W9CW

I've owned a Bird 43 wattmeter for years, and have decided to purchase either an Array Solutions Power Master II or the Telepost LP-100A. 

Any comments, as to "Pros" and "Cons" of each.  It appears that both are very accurate traceable to NIST standards, but am looking for user comments as to user-friendliness, reliability, the included software for interfacing to a PC, customer support, etc. - i.e. overall satisfaction.

Tnx,
Don W9CW

As per Dick's advice, I did clean the spring-loaded contacts, or wipers, that ground each section of the Loading capacitor with DeOxit.  Interestingly, the SB-200 was covered with a custom cover during the 5 years of storage on a shelf near the ham shack.  All temp and humidity controlled... I guess some contamination can occur even with the temps at 70 to 78 degrees, and 30 to 40% humidity.  I even had a couple of desiccant bags beneath the custom cover during those 5 years.  Things just happen...  the old adage "use it or lose it" also applies to electronics.

Nevertheless, all is now well - working on all bands FB.  Plus, I now have an almost inaudible cooling fan! But, that's another topic all together.

Tnx to all.

73
Don W9CW
 

Dick,

You were spot on with your assessment!  I cleaned the wiper of each capacitor bank of the Loading cap carefully with DeOxit, and all is well now.  I am now actually able to peak the output throughout 80 and 40 - even at the bottom end of 80 and 40 without running out of C.

Thanks for the tip... that's one gremlin that I must admit, I didn't think of - ashamedly. 

73
Don W9CW

Dick,

Good advice, as I missed that step!  I will clean the wipers on each section of the loading variable tonight.

I should have been more specific when I used the term "wafers."  I cleaned all of the switch wipers and the contacts on each wafer as best I could with DeOxit - not the spray, as it always supplies too much, but the pen - and, very, very carefully, a long Q-tip.  As best as I can tell, all contacts are now clean.  After I'm sure there's no residual voltage in the tank circuit, I will double-check for continuity at each switch point with my Fluke 77 also tonight.

As an ex-Navy Leading ET, who worked on surface and air search radars, as well as communications gear aboard a destroyer, I have keen experience with a "shorting stick" and working with one hand tied behind my back when HV is present.    One can never be too careful.

Tnx,
Don

This SB-200 typically requires around 70 to 75W drive for full output, but I normally drive, and load, the amp with the full output of the Omni (100W).  The grid, and plate, currents are always in the safe area.  I do have to watch the plate and grid currents when driving it with 100W, but as previously mentioned, I never allow either to go above the safe levels.  Nevertheless, the Loading control always wants to be fully meshed, thus I really can't peak the output, regardless of the drive level from 70W to 100W. The output does increase when I fully mesh the Loading cap of course, but I never see a peak.  I was always instructed back in the early '60s to drive an amp with the exciter at full output for the tune/load procedure, and I've always adhered to that tenet.  But, then again, I've always owned grounded-grid linears.

Last night, I did carefully clean all switch wafer contacts with careful use of DeOxit.  No change...

I do have a 500pf @ 3kV cap in my back stock.  I think I will remove the existing 500pf padder, solder in the replacement, and see if this affects the loading on 80.  But, that still doesn't explain what may be going on with 40.

I must admit, this one has me a bit stumped!  Thanks for the advice.

I have a SB-200 that I built in the mid-70s.  I recently updated the SB-200 with all of the Harbach mods (power supply, soft start, soft key, and fan).  Prior to the addition of the Harbach upates, it had set on the shelf for around 5 years.  The tubes are not the originals, but I replaced them about 6 months prior to placing it "on the shelf" with USA made NOS Cetron 572Bs.

I know the proper procedure for tuning the amp, as to the plate (Tune) and Loading controls.  I always start with the Loading control at the "4" position on the dial, which is around the 10 to 11 o'clock position.  I always get a good dip with the Plate (Tune) control.  I generally use the Relative Output position on the SB-200's meter, and my wattmeter for peaking the output.

Here's what's happening:  While tuning into a known-good 2kW-rated Bird 50 Ohm dummy at full drive with an Ten-Tec Omni, and attempting to peak for max Relative Output (SB-200 meter while keeping grid and plate currents in the safe region of course), the loading cap wants to be fully meshed, e.g. under-coupled, on 80 and on 40 (BTW... it acts the same way on resonant dipoles).  On all other bands, the tune-up procedure is fine.  I can never peak the output on 80 or 40, as I'm running out of loading capacitance.  Under-coupling an amp is bad in many ways, so I'm trying to figure out what's causing this problem.  The 1,000pf and 100pf doorknob caps are original.  I do get normal, or close to normal, output on all bands, but again, the loading cap is fully-meshed on 80 and 40, and I'm not able to truly peak the output on those two bands, unlike on 20, 15, and 10.

I remember having a slight problem before on the low-end of 80 years ago, but never on 40.  If it was only on 80, I would certainly look into the 500pf mica padder that's in the loading circuit on 80, but why on the problem on 40?  Any thoughts would be appreciated.

Tnx,
Don W9CW
 

The stock filter in the 509 is a 2.4kHz to 2.5kHz 4-pole xtal lattice filter.  Typically, if the 509 is sent in to Ten-Tec for any repair, they upgrade the filter to a 2.4kHz 8-pole xtal lattice filter.  Like the Triton series, 540, 544, and the original Omni D, the CW filters were audio filters only - no option for a 500Hz or so xtal lattice filter.  The Omni Series B and Omni C corrected that by providing a PIN diode-switched board for adding a narrower SSB xtal lattice filter (1.8kHz) and a CW xtal lattice filter (500Hz).

The early Ten-Tec rigs, including the Argo 505, 509, 515, and all those mentioned above, used audio-derived AGC - not I.F. AGC.  The Model 208 filter option for the 509 was an audio filter built with op amps.  However, unlike most other outboard audio amps that are used with the headphone or speaker outputs, the Ten-Tec 208 audio filter was within the audio-derived AGC loop.  Therefore, out of passband signals would not pump the AGC.  You can certainly use a 3rd party outboard audio filter (Autek, Datong, MFJ, et. al.), but they will not work as well as the Ten-Tec Model 208 outboard audio filter, as they are not within the AGC loop.

With my 509, I added the audio notch filter board from an original Omni series to the 208, plus there is one additional op amp filter BW that can be used with the stock 208.  You just need to change the position of the filter switch stop, and you will have a total of 4 audio filter BW positions, plus the notch filter should you add the board to the 208.  With this combo, the Argo 509 and 515 make excellent QRP CW rigs.

I second the motion to read the info available on the repeater-builder.com website. 

Astron has made running changes on the design of the RS-35 series, in addition to their other supplies, and sometimes it's hit and miss.  Not to open Pandora's Box here... as there is a continual debate, including on the repeater-builder.com website, as to the technical pros and cons of bonding the negative post of the 13.8VDC output to the supply's chassis ground.  Most technically-astute hams, including the aforementioned website, state unequivocally that the negative post should not be tied to the power supply's chassis ground.  Nevertheless, rumors have it that Astron tied the negative post to chassis ground to eliminate RFI effects upon the voltage regulator IC. 

Open up your supply and look to see if there's a jumper from the negative post to chassis ground.  If indeed Astron added this jumper to theoretically reduce or eliminate regulator RFI problems, they didn't implement it very well.  The "grounding jumper wire" from the negative post is tied to a point on the bottom of the supply's chassis through a star washer, but the chassis is painted and most of these jumpers do not effectively ground the negative output post.

The best solution is to investigate any source of RFI problems induced by your antenna or inadequate station grounding (not from a DC perspective, rather from a RF perspective).  Remember, a DC ground and a RF ground are entirely different animals...

Best of luck.

73
Don W9CW

I received an e-mail from Fred Lloyd of QRZ.com, and he added this in the "Stolen Radios, Scams, and Rip-Offs" forum in the endemic thread (Scam: Icom 756 Pro III) on QRZ:

"Editor's Note
W9CW did not offer this radio for sale.

Earlier today, someone came in and requested a password for the account and had it sent to an offshore address. The requester then posted the item for sale.

Fortunately, the QRZ support system immediately notified the REAL W9CW and we shut it down, and deleted the ad. We have also conducted a review of our password retrieval system and have made changes that will prevent this sort of thing from happening again.

QRZ wishes to apologize to Don, W9CW, and others who were affected by this vandal.

Fred, AA7BQ"

Good point... I keep up with my PC's security daily with a hardware firewall, a paid software firewall, and paid AV (Avira), but anything can happen this days.  Plus, I don't do any stupid browsing.  I do wish QRZ would make it a bit more difficult to change account settings, e.g. a security question or some other hurdle.  This is the first time I've ever had such a problem after decades of computer use.

73
Don W9CW