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Re: D-104 fix
FWIW, crystal microphones have not been made for many years. Old ones should be avoided if you want a practical, working microphone. In some cases ceramic versions were made with similar performance,
By Richard Knoppow · #29987 ·
D-104 fix
g'luck... most of the original elements have gone bad... a few still linger.? Caveat Emptor Grasshopper...? An article in ELECTRIC RADIO some time back showed the use of KOBITONE elements, which
By Tom Dailey · #29986 ·
Re: HT-44 - unwanted sideband suppression level?
This is off topic. I need the crystal mic elements found in a 104 mic ! went to a ham feast, (does it work? oh absolutely NOT! also a hand full of the mic connectors used in hallicrafters (ht 37, ht
By Dan Hoag · #29985 ·
Re: HT-44 - unwanted sideband suppression level?
Hi, Walt The HT-44 manual (beginning of Section II, Northrop version) says: Unwanted Sideband Rejection 50 DB or more at 1 KC. 30 DB or more, 500 to 2500 CPS. Norgaard, in his article on the G.E.
By k2orsfan · #29984 ·
Re: HT-44 noise on microphone input
Shields ¨C in the broadcast world we connect the shield at only one end to avoid hum/buzz pickup, BUT in high RF environments or where conveying RF is required, we connect both ends of the shield.
By Mike Langner · #29983 ·
Re: HT-44 noise on microphone input
Thinking it through...that's probably right.? Our cables, of course, ran from one location (switch or hub) to the jack for the computer, so no common metal. Tom Latimer
By Thomas Latimer · #29982 ·
Re: HT-44 - unwanted sideband suppression level?
I've been over S3B multiple times and it's clean and all contacts are functioning as they should.? The signal arriving at the grid of the first mixer looks flaky on the scope - not a stable sine
By Floyd - K8AC · #29981 ·
Re: HT-44 noise on microphone input
I think that's been covered in previous comments.? My current belief is that when the cable joins entities that are not in the same enclosure, leaving one end ungrounded may be the way to go.? But
By Floyd - K8AC · #29980 ·
Re: S20R project
I needed to add another "thanks" note to this thread, since I see the additional wealth of detailed information posted here - definitely this is THE place to seek advice!? It may be another week or
By Bruce KX4AZ · #29979 ·
Re: HT-44 - unwanted sideband suppression level?
The 44 should make -65 to -70db unwanted sideband suppression. Inability to get a good reduction of the unwanted sideband points to audio distortion in the mic amp/modulator train or S3B switch
By waltcates · #29978 ·
Re: HT-44 noise on microphone input
Floyd, Just a thought....sometimes grounding both ends of a cable can cause noise loops.....I pulled a lot of cable back in my youth (Ethernet unshielded TP) but if we had to pull shielded we made
By Thomas Latimer · #29977 ·
Re: HT-44 noise on microphone input
I installed a new piece of shielded cable, both ends grounded, from the mic connector to the first mic audio stage and moved the .001 cap to the tube end where the leads could be much shorter.? Also
By Floyd - K8AC · #29976 ·
HT-44 - unwanted sideband suppression level?
Making slow progress on the HT-44 but am now able to get very good carrier suppression but don't know what to expect for unwanted sideband suppression.? I can get it down to 50-55 dB below the wanted
By Floyd - K8AC · #29975 ·
Re: S20R project
I have never had much luck in restuffing caps, just don't have the skill. Mostly use separate caps under the chassis but sometimes they are hard to fit in place. -- Richard Knoppow Los Angeles WB6KBL
By Richard Knoppow · #29974 ·
S20R project
Having developed a fairly easy method for restuffing my OWN can caps, I prefer them.? Hayseed produces a very workable product, but the terminals aren't always oriented in the same pattern or
By Tom Dailey · #29973 ·
Re: S20R project
It sounds like you have enough stuff to get going. Jim Whartenby asked good questions I should have asked. The can cap can be replaced by individual caps under the chassis but make sure NOT to just
By Richard Knoppow · #29972 ·
Re: S20R project
BruceGood to know your skill set!? Curious to know if the power switch has been bypassed or if it has failed in the ON position which is rare, IMHO.? That penetrating oil trick works well so give it
By Jim Whartenby · #29971 ·
Re: S20R project
Maybe add an inrush limiter, too. KK3HVG
By D. Platt · #29970 ·
Re: S20R project
Most of the tubes in that radio will get warm when the radio is on for more than 10 minutes, and that is a good indication if the filament is good, recapping should be done first, as damage can be
By Scott Petersen · #29969 ·
Re: S20R project
Thanks all for the detailed replies, it is wonderful to hear from S-20R veterans that have "been there and done that". Some more details on my skill background to help tailor your advice.? I am fully
By Bruce KX4AZ · #29968 ·