Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12) x

Thread Closed
Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

hallicrafters sx-43 NO FM
#8

Quote:but the 3rd step if adjustments had no effect,band four is very quiet with no static ,but will pull in a station at night.
+1, the shortwave band in question, however, lacks sensitivity. Since the BC band pasess through the IF and that is OK...

Lack of sensitivity can be attributed to at least four obvious things, more, if nits are to be picked...

1 - The RF or mixer tube isn't up to snuff of there is low plate voltage...

2 - There is poor "Q" in the RF/osc coils the signals are lost in "wet" coils

3 - There is a ground connection to the chassis via a rivet that is failing.

4 - There is a leaking mica bypass cap, could be one associated with tuning or the oscillator.

5 - Propagation is poor.

6 - What ever antenna is poor or your location is, for shortwave.
-------------------------------------------------------------------------------------
#2 can be very difficult to address. Gently warming the coils in question with a heat gun will drive off moisture...

#3 The plated chassis and the rivet react with time to set up a corrosion. Even though the connection can be measured at zero ohms, that is DC not RF. Burnish such a riveted connection with a wire brush, add small amount of ACTIVE water base flux. Apply heat from iron with large copper tip and rosin solder. If all is well solder will flow around rivet, solder-tab and chassis without forming a ball. Using a heat gun to warm the chassis helps. Alternate fix: Drill out rivet replace with hardware and serrated washers.

#4 A "special" heat gun with a silicone rubber nozzle can be used to find a leaking mica or freeze spray. In the RF the effect is either drifting of the signal or the signal fading. If the signal increases then the tuning needs work.

Any alignment adjustment that does not peak or null as expected is a problem area. Components and connections associated with that adjustment will have to be inspected.

Great so far!

Chas

Pliny the younger
“nihil novum nihil varium nihil quod non semel spectasse sufficiat”


Messages In This Thread
hallicrafters sx-43 NO FM - by falcon123 - 02-15-2020, 12:56 AM
RE: hallicrafters sx-43 NO FM - by Chas - 02-15-2020, 04:37 PM
RE: hallicrafters sx-43 NO FM - by Radioroslyn - 02-15-2020, 04:59 PM
RE: hallicrafters sx-43 NO FM - by falcon123 - 02-15-2020, 09:43 PM
RE: hallicrafters sx-43 NO FM - by falcon123 - 02-15-2020, 10:26 PM
RE: hallicrafters sx-43 NO FM - by falcon123 - 02-17-2020, 01:29 AM
RE: hallicrafters sx-43 NO FM - by falcon123 - 02-28-2020, 06:24 AM
RE: hallicrafters sx-43 NO FM - by Chas - 02-28-2020, 11:24 AM
RE: hallicrafters sx-43 NO FM - by falcon123 - 02-29-2020, 11:00 PM
RE: hallicrafters sx-43 NO FM - by Chas - 03-01-2020, 12:15 AM
RE: hallicrafters sx-43 NO FM - by falcon123 - 03-01-2020, 03:48 AM



Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Need to purchase some accessories for restoration of my Old Philco Radio
Hi Paulo, Welcome to the Philco Phorum. I can see why you want to find good reproduction parts. That is a bea...MrFixr55 — 11:10 PM
HiFi (Chifi) tube amp build - but my own design.
Tim, I have some bakelite sockets in my work shop that I can dig up. I believe quite a few are NOS. I will take photo...RodB — 10:03 PM
Philco 610B oscillator wiring
> The cathode as noted is wired directly to the ground side of the heater filament for that tube, not to the #17 and ...Radioroslyn — 08:12 PM
HiFi (Chifi) tube amp build - but my own design.
Tim; I noticed your post a little late, but I would take one of the junk sockets and try to break a chunk out of it wi...Arran — 08:07 PM
Need to purchase some accessories for restoration of my Old Philco Radio
Here is a list of resources found in our online library that you might find useful. Mike's Gobs of Knobs email addres...klondike98 — 01:46 PM
First Radio restoration
Hi Tubeman, Welcome to the Philco Phorum.  Phamily Phriendly Pfun with Phine Pholks Phull of Philco Phacts. (See a p...MrFixr55 — 12:33 PM
First Radio restoration
You could post in the WANTED ADs section here on the Phorum and see if anyone has an RF generator that they want to sell...klondike98 — 11:55 AM
Zenith H725
Good ideas, thank you Arrange and Rich. I have the adhesive aluminum foil already and can try that immediately. More ...EdHolland — 10:18 AM
Graphics for majestic 1050 dial glass.
Murf; I found this thread on the ARF, the first photo has a pretty good view of the dial glass. Regards ArranArran — 01:12 AM
Zenith H725
hello Ed, how about that speacial tape used for ducting it's like foil or how about thin piece of aluminum roof flash...radiorich — 12:19 AM

[-]
Who's Online
There are currently 1450 online users. [Complete List]
» 2 Member(s) | 1448 Guest(s)
AvatarAvatar

>