As the others posting have mentioned, the delta loop is a full wavelength antenna and does not require ground radials.

I have 3 Delta loops.  Two are cut for 80M - one is suspended horizontally, the other is an inverted vertical and fed at the bottom.  The BIG one is a 570 foot loop, up at 60 to 80 feet, and fed with homemade 450 ohm open wire line.  All are "matched" using a Tee type, band switched tuner which has a short RG-8X coaxial feed line out to a remote Balun Designs 4:1 balun (Bob makes some really nice balun's).  The 80M inverted delta uses some 300 ohm window line, and the 80M horizontal uses some W7FG 600 ohm open wire line (only because it began life as a W7FG 160M dipole - I just closed it up and kept the feedline in place).  The 2 smaller loops are now used very little since I put up the BIG loop.

I find that a 4:1 balun is necessary, using my Tee type tuner, if I make large excursions from the native resonance point of the loop - my BIG loop is easy to load on 160 thru 10M - just a bit "iffy" on a portion of 15M.  

I suspect that one day it will even work better, once I get my Heathkit SA-2060A on-line.  I had Bob construct a current balun for the Heathkit, to replace the voltage balun.

Matt Erickson (KK5DR) recommends an inductance value between 30 and 300 microHenries to be sufficiently robust to cover 160 thru 10M.  His writeup on "Building your own tube-type amplifier" is well done and has some excellent construction information and techniques.

The ferrite mix does not appear to be a critical factor.

Visit his web site http://kk5dr.com/ampbuilders.htm and send him an e-mail.  Matt is a great guy and is very willing to share his knowledge of amp construction.

On his suggestion, I changed my plate parasitic choke to a more stable design.  No longer is it the old, typical wire wrapped around the 100 ohm resistor.  And it is much more stable on 10M.

"But if he runs into a tougher RFI problem, which he WILL if he gets an amp, you really gotta get the real deal, the FT-240-43"

Those cores are what I used on my PS2 cable for the computer mouse AND the keyboard.  The keyboard was getting squirrely on 80M and the mouse on 20M.  The cores solved the problem.  Got an assortment from a fellow on eBay...at a good price.  I tested some with a few turns of wire thru them and attached to my MFJ259B

When I added the SB-1000 amp into the mix, I experienced some RFI problems on 40M - not with the computer but my Mastech dual output power supply on the repair bench.  I could hear the relays clicking in the power supply, activated by the SSB voice peaks.  Yes, I could have just turned off the supply but the RFI would still have been floating around in here and I wanted to resolve the problem, if I could. My HP spectrum analyzer, with a short whip antenna, clearly showed the signal.  The Folgers coffee can choke solved that problem (a picture of it on my QRZ page).


 

How is the mouse acting?  Any sporadic problems?

Your keyboard ferrite placement may be the result of using the USB port.  On my HP, I plug into the keyboard connector on the rear of the chassis.  In addition, the choking impedance of the ferrite snap-ons are probably much less than the cores I used.

In any case, glad it worked out for you.  If you install an amp someday and have problems, remember my Folgers coffee can choke approach.  Ugly, but it worked out.

All Electronics has a nice selection of ferrites at reasonable prices.  http://www.allelectronics.com/make-a-store/category/235/Ferrites/1.html

I own a 2060A but I think the L1 rotary inductors are similar in construction.  The inductor friction level is controlled by a screw threaded into the REAR shaft.  There is a bushing on the inner side of the plexiglass panel that the inductor shaft passes thru.  The outside of the bushing is threaded and a nut threads over the outside of the bushing on the outside of the plexiglass plate.  The level of friction is adjusted with a screw which threads INTO the rear shaft and squeezes down on the outside of the end of the bushing.

Remove the set screws and get a small tube of Locktite blue (low pressure thread lock breakaway - the Locktite red requires a big wrench to break it free).  Auto Zone and other auto parts stores carry it.  The Locktite blue will prevent the set screws from loosening under normal use.  Just a single drop on each setscrew threading will do the trick.  Carefully thread the setscrews back in place.  If in doubt, once the setscrews are partially installed, apply another single drop to the top edge of each and finishing tightening.  The Locktite will wick down the threads and set up in a short time.  Normal vibration will not cause them to work free.

You may also wish to use some silicone spray on the front and rear shaft bushings and the roller pick-up wheel.  I would not recommend WD40 or any other type of oil.  They have electrical insulating qualities - the silicone spray does not.  I purchased a 7 oz.can of CRC with an extension spray tube (helps to get into tight spots) @ Home Depot for around $4.  Works well on roll-up garage door wheels, too.  Doesn't attract dirt and lubricates nicely.

SmallParts and McMaster Carr carry the "two hex screws per side" style couplings you refer to in your posting.  They are available in plastic and stainless, slotted and non-slotted, and aren't cheap.

Out of despiration I made one (not for my 2060A but for another tuner - a Nye Viking MB-IIA).  A piece of appropriately sized steel tubing, drilled at the correct locations, and a metric tap to cut the threads for the set screws.  Necessity is the Mother of Invention.

Hope this helps.

Howard Walker
KI4VEO

I had a similar problem with the keyboard and my mouse.  At the time I began my investigation I had no snap on ferrites but a good selection of cores used to wind rf transformers and baluns.

The problems with both the keyboard and mouse were resolved by winding 5 or 6 turns of the respective cables thru the cores very close to the end connector that plugs into the pc.  I would suggest positioning the ferrites there - perhaps more than one, if necessary.

This worked well until I added the Heathkit SB-1000 amp.  The problems resurfaced, with some additional ones, only on 40M.  I ended up winding a 1:1 coaxial choke - 25 turns of RG-8X around an empty plastic Folgers coffee can with the turns held in place with some Ty-wraps.  The common mode choke resolved all the problems.  The choke is pictured on my QRZ page.

Howard Walker
KI4VEO

The only place I use coax is for rig interconnects.  Outside the shack window it strictly open wire feedline...the REAL open wire line.  No vinyl window line stuff...it gets iffy when wet or covered with ice.

My BIG delta loop (560 feet of wire @ 70'), 200 feet of 450 ohm line and a 4:1 balun = a strong signal.

Having a Malcomized FT-102 and a Heathkit SB-1000 doesn't hurt, either.

And the smaller birds seem to like the open wire line as a place to rest.

Just trying to help out the restoration buffs when I can.

I keep a bookmark list of old parts locations and consult them as necessary.

Have fun fellows...and keep the old rigs on the air.

Howard

After you described the RCA connector I knew just where to find 'em.  Surplus Sales isn't cheap but they have a good selection of OEM boatanchor parts.  Bookmark the web site for future reference.

Sometimes you can find stuff like this at Fair Radio Sales: http://www.fairradio.com/

Surplus Sales:  http://www.surplussales.com/Connectors/RCA-1.html

This ceramic two ear lug type was used by Collins, too.

Radio Shack should be convenient:  http://www.radioshack.com/product/index.jsp?productId=2103224

I keep thinking one day someone will go off the deep end and show up at his door with revenge on his agenda.

This fellow with the Dentron amp has a legitimate axe to grind.  I remember seeing his eBay ad when it was first listed back in January.  I have an eBay search on file for "Dentron Amplifier" hoping to find a MLA2500 chassis for a conversion to 3CX800A7 tubes.  Yes, I see one up there now but I want to do the conversion myself.

Giving Marty the benefit of the doubt I suppose he just sees himself as a shrewd businessman and someone that is entitled to take advantage of opportunities and trusting people without any feelings of remorse.

That pretty much defines a sociopath.  They make the best used car salespeople and politicians.

Another amateur op falls prey selling to Marty:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=160563429073&ssPageName=ADME:B:SS:US:1123

Well maybe gone from eBay, but not, "Gone for good."  This just showed up in my e-mail Inbox:

Dear Valued Customer;
Please come visit our NEW SITE!  It is finally finished, and we are very pleased with the work that has been done.  We trust you will find the site, informative, easy to navigate and hope you will add us as a Bookmarked favorite!


                                    www.radio-mart.net






To our Friends in Japan...  our hearts & thoughts are with you at this very trying & frightening time.




Many Thanks & Have a Blessed Day
Leslie Allison
859.312.3857 (mobile)


NEVER pay excessive e-Bay fees again!!!
Visit www.webstore.com to find out HOW!
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[ Sorry - a good thread is a thing of beauty and should not be wasted. ]

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The good ones play...the GREAT ones play hurt.

I agree...it sounds like RF is getting back down the coax and into the radio.

After eliminating the plausible, look to the implausible.  I gave up on fan dipoles because of the interaction problems, but that does not seem to be what you are experiencing.  You might just consider a 270 foot loop and a decent tuner.  The loop is your friend, it works pretty well and isn't too difficult to put up.

If you insist on a dipole, then begin with a single band and add-on.  Try a 40M dipole and use it as a 3/4 wave on 15M.  If it works, and no audio problems, then try adding 80M and see what happens.  It could be something as simple as the proximity of the antenna to the shack or the length of your coax.