Thanks Mark. Although I have been dabbling in tube radios for some time, I hadn't personally come across the "humdinger" technique, though I note it's quite a...
894
Philip
kmg5443
Apr 1, 2012 3:01 pm
Some folks think we are dead!!! Reports of this group's demise are highly exaggerated, I hope!! I think the activity of kepptheremins goes in spurts,...
895
Philip
kmg5443
Apr 1, 2012 3:02 pm
I added the hum bias pot and it cured my issues. However, the position of the wiper on the pot seemed to make no difference whatsoever. It worked no matter...
896
Mark Keppinger
klickitatcri...
Apr 1, 2012 4:31 pm
Pete; Philip notes that this helped his hum, but the position of the pot didn't make any difference. This is because the filament winding is otherwise...
897
James
jhoneycutt11
Apr 1, 2012 7:13 pm
Hi folks... Long time not talk. I have been busy with other stuff. It is time for me to buy the two transformers in Mark's, original "classic" vacuum tube...
898
Charles MacDonald
cmacd123
Apr 1, 2012 10:44 pm
... Hamond has a number of US distributors. Trick is that transformers are expensive to ship, so if you can get them from a local place, so much the better....
899
Mark Keppinger
klickitatcri...
Apr 1, 2012 11:48 pm
Correct. I got mine from Radar Electric (now out of business; at least here in Portland) with no added shipping costs. WOW! ... From:...
900
Richard Watts
jrwatts4
Apr 2, 2012 12:07 am
I purchased my Hammond transformers from RadioDaze and found that they have competitive prices. Their website is at <http://www.radiodaze.com/> ...
901
rrr.weldon
narc.callahan
Apr 2, 2012 1:38 am
I also got my transformers at RadioDaze, as well as a bunch of other stuff for the Kepp my partner and I built. It was several years ago, but I remember the...
902
GTC
gtc131
Apr 2, 2012 6:39 am
Many thanks for the kind offer of the hole punch. I won't be making the chassis myself as metalwork is not my forte. I have made chassis as a kid but I was...
903
AriT
aritepper
Apr 2, 2012 7:23 pm
Were have you been able to find the 4.7mH Iron Core Inductor? Ari...
904
AriT
aritepper
Apr 2, 2012 7:29 pm
Has anyone been able to locate the exact coil forms that Mark has specified for the air inductors? Either I'm looking in the wrong place or just not looking...
905
mkepp@...
klickitatcri...
Apr 2, 2012 8:07 pm
Ari; I got the originals for my design from Cascade Surplus here in Portland. Tony may be closing the doors, selling out, or going mail order only in the near...
906
mkepp@...
klickitatcri...
Apr 2, 2012 8:10 pm
Ari; These are available from Red Arrow Hobbies. They are sold as rocket body tubes for the model rocketry hobby. They have occasionally thrown in a few...
907
GTC
gtc131
Apr 2, 2012 10:43 pm
I recently ordered a set from Charlie Hobbs....
908
GTC
gtc131
Apr 2, 2012 10:44 pm
Good question. I can find ferrite versions, but not sure they meet Mark's spec. Perhaps Mark can comment on that....
909
mkepp@...
klickitatcri...
Apr 2, 2012 10:51 pm
Ari; Okay, you got me there. I grabbed one of these chokes for my original prototype, and it worked great, so I bought a bunch, and that's what I used....
910
GTC
gtc131
Apr 4, 2012 10:44 am
Just confirming that the value range for this cap is 5-15pF, correct?...
911
Mark Keppinger
klickitatcri...
Apr 4, 2012 2:49 pm
Yes. It's a panel mount capacitor with 1/4" shaft made from a larger value with all but one or two of the rotor plates pulled out. If you don't have anything...
912
GTC
gtc131
Apr 5, 2012 7:54 am
Thanks again Mark. I don't have anything like that handy, so I'll email you....
913
GTC
gtc131
Apr 5, 2012 8:07 am
I'm leery of issues caused in amplifier circuits by ground loops and have been taught that the fewer grounding points the better. As my mains power is 230v...
914
Mark Keppinger
klickitatcri...
Apr 5, 2012 3:47 pm
One of the two 6-pin connections is power ground; the other is signal ground, connecting to the shield. They both electrically ground. E-mail me your mailing...
915
GTC
gtc131
Apr 5, 2012 4:21 pm
Thanks for the explanation, Mark. Yahoo truncates email addresses online, which is how I access this Group. I have sent you a message via the Yahoo Group's...
916
Philip
kmg5443
Apr 5, 2012 4:30 pm
My army leadership training at Ft. Belvoir is almost over....coming home tomorrow...YAAAAYYYYY!!!! Philip...
917
Laurence Vesyoly
larryvesyoly
Apr 6, 2012 4:09 am
Hi All, I just finished building a theremin using Mr. Keppinger's design and have begun testing. So I have a few questions. I haven't dealt with tube audio...
918
Mark Keppinger
klickitatcri...
Apr 6, 2012 4:54 am
Laurence; Good questions. 1. You can solder a "bleeder resistor" across the filter capacitors. The time to discharge to 67% of the voltage is calculated by T =...
919
GTC
gtc131
Apr 8, 2012 4:51 pm
Hi Mark, I emailed you but have since found and purchased an HFA-15-B online. Specs are 2.8-16pF so I guess that's close enough to the 2.8-17.5pF of the HF-15,...
920
GTC
gtc131
Apr 8, 2012 6:27 pm
Small iron core chokes seem to be thin on the ground, whereas ferrite is everywhere. So, what have folks used for L3?...
921
Mark Keppinger
klickitatcri...
Apr 9, 2012 1:34 am
Sounds like you're good to go! ... From: kepptheremins@yahoogroups.com [mailto:kepptheremins@yahoogroups.com] On Behalf Of GTC Sent: Sunday, April 08, 2012...
922
Mark Keppinger
klickitatcri...
Apr 9, 2012 1:35 am
No matter what you use, you will get results, but they may vary the distance your hand is away from the antenna at a certain volume, which can be tuned (to a...
