Gilfillan radio? - Printable Version
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RE: Gilfillan radio? - Eric - 09-16-2015
Well I ordered the inter-stage transformer and I installed it and brought it up slowly, it draws .3A at 115v and I get stations especially at the high end of the dial then it seemed to die off as I went lower so I added about 30 ft more to my antenna and attached the ground and got more volume and more stations at the lower end of the dial. I'm surprised at the clarity of the sound as I had never seen a speaker like that before.
Thanks to all for the help.
Eric
RE: Gilfillan radio? - Arran - 09-17-2015
Eric;
It probably just needs an alignment, which is not too hard to do on a simple TRF set like this. You more or less need to set it to a station near the mid point of the dial and tweak the trimmers there is such a way that you still get stations at both ends of the dial. Since it's basically an electrified 1920s battery set anyhow it's not going to be a real powerhouse with only six tubes, well five since one is the rectifier tube.
Regards
Arran
RE: Gilfillan radio? - Eric - 09-17-2015
(09-17-2015, 12:30 AM)Arran Wrote: Eric;
It probably just needs an alignment, which is not too hard to do on a simple TRF set like this. You more or less need to set it to a station near the mid point of the dial and tweak the trimmers there is such a way that you still get stations at both ends of the dial. Since it's basically an electrified 1920s battery set anyhow it's not going to be a real powerhouse with only six tubes, well five since one is the rectifier tube.
Regards
Arran
Arran
No trimmers on this radio, nothing on the tuning condenser, or on top of the chassis or underneath the only thing that makes a difference is the length of the antenna. I guess this is a pretty primitive radio. The other thing is the resistors, I have no idea what their values should be as the color code used is not the standard this could be part of the problem?
One of the resistors (blue/violet?) reads 2.5meg it goes from the "27 tube pin3 grid to chassis.
The tube data that I looked at said no more than 1 meg resistance in the grid ckt.
RE: Gilfillan radio? - Mondial - 09-17-2015
Eric, don't expect a lot of performance out of that radio. Its a primitive circuit and a cheap implementation of it at that. Be happy that it works at all. If you don't have powerful local stations, you really won't hear much without a long antenna.
As far as the 2.5 Meg resistor, that's the grid leak for the detector tube and its about the right value. The Atwater Kent model 40 has a similar circuit and uses a 2 Meg resistor in the 27 grid circuit. A higher resistance actually makes the receiver more sensitive. The tube data you saw was probably for using the 27 as an amplifier not a detector, so the 1 Meg max resistance does not apply here.
Glad you got it working after all the work!
RE: Gilfillan radio? - Eric - 09-17-2015
(09-17-2015, 03:49 PM)Mondial Wrote: Eric, don't expect a lot of performance out of that radio. Its a primitive circuit and a cheap implementation of it at that. Be happy that it works at all. If you don't have powerful local stations, you really won't hear much without a long antenna.That's pretty much my feeling, I really don't plan to run it so now I will refinish the cabinet and put it on the shelf.
As far as the 2.5 Meg resistor, that's the grid leak for the detector tube and its about the right value. The Atwater Kent model 40 has a similar circuit and uses a 2 Meg resistor in the 27 grid circuit. A higher resistance actually makes the receiver more sensitive. The tube data you saw was probably for using the 27 as an amplifier not a detector, so the 1 Meg max resistance does not apply here.
Glad you got it working after all the work!
RE: Gilfillan radio? - Eric - 09-17-2015
(09-17-2015, 03:49 PM)Mondial Wrote: Eric, don't expect a lot of performance out of that radio. Its a primitive circuit and a cheap implementation of it at that. Be happy that it works at all. If you don't have powerful local stations, you really won't hear much without a long antenna.I will leave it as it is and refinish the cabinet
As far as the 2.5 Meg resistor, that's the grid leak for the detector tube and its about the right value. The Atwater Kent model 40 has a similar circuit and uses a 2 Meg resistor in the 27 grid circuit. A higher resistance actually makes the receiver more sensitive. The tube data you saw was probably for using the 27 as an amplifier not a detector, so the 1 Meg max resistance does not apply here.
Glad you got it working after all the work!