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Philco 84 Low Volume - Printable Version

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Philco 84 Low Volume - dconant - 10-09-2025

Hello,  I have a Philco 84 on the bench that has been recapped. Works but volume is low. Any reason for that and can it be made better? I'm thinking since a it a regenerative radio volume might be low with distance stations. Mostly all for my area. I have to have volume all the way up for my favorite station. I have done an alignment with generator connected to the ant connection. Instructions don't say where to connect.

Thanks, 
Dan

RE: Philco 84 Low Volume - dconant - 10-09-2025

I'll reply to my own thread. I have since learned to connect the generator to the grid of the first 77 tube. Made no difference in the alignment. I'm now thinking low volume is just a problem on stations further away. I think I detect a little bit of distortion when music is playing. Is this normal? I only get music on distance stations. Lots of gab in my neck of the woods.

RE: Philco 84 Low Volume - RodB - 10-09-2025

One thing I noticed in working on the few regenerative radios that have come my way is that the tube pins and sockets must be cleaned.

RE: Philco 84 Low Volume - radiorich - 10-10-2025

Hello kevin,
I have found the same issue as what Rob said !

Sincerely Richard

RE: Philco 84 Low Volume - Radioroslyn - 10-13-2025

If you want to do a little troubleshooting here's what I'd do. Unplug the set and turn the volume full up. Measure the resistance from the ANT post to chassis ground. Should see a low resistance like 3 or 4 ohms. Higher than that indicates an open primary winding on the ant coil. 

Unsolder the wire connected to the wiper on the volume. Measure the resistance from the wiper to ground with a analog meter. Any erratic movement would indicate a dirty or worn out carbon track within. Most of the time it fail near the grounded end of the pot.

On coil #10 find the connection that has a 6000 ohm resistor & a mica cap. Measure the resistance from that point to ground. Should see a low resistance like 3 or 4 ohms Higher than that indicates an open feedback winding on the oscillator coil.

Measure the resistance from the 2nd 77's grid cap to the chassis. Should see about 4 meg. If it's a bit higher it doesn't effect the sensitivity it effects the distortion and selectivity.

Block #20 be sure that the two caps are in the proper order. If switch you'll have muffled and low audio.

https://philcoradio.com/library/download/service%20info/service%20bulletins/Philco%20Service%20Bulletin%20178.pdf

RE: Philco 84 Low Volume - dconant - 10-13-2025

Hi Terry, Thanks for the help. I will check these and let you know.

Dan

RE: Philco 84 Low Volume - dconant - 10-13-2025

Hi Terry here are my results.

First item - 3.8 ohms. I did rewind that coil.
Second item - No erratic movement detected. It is a new pot from Mark Opat.
Third item - 2.3 ohms.
Fourth item - 2.9 meg. I replaced the 4 meg resistor (#16) with a 2 meg based on another post.
Fifth item - Block 20 as well as 9 were missing from my radio. I have checked the location of the block 20 caps four times and they are correctly wired. I did add the block 9 caps as shown in the schematic.

A third go around with the regenerative condenser helped a little bit. So I guess I'm good then. Maybe I'm expecting too much.

Dan

RE: Philco 84 Low Volume - Radioroslyn - 10-13-2025

Ok so all that sounds good round two begins. I trust you checked #'s 18, 19, and 22, to be with tolerance. 

When adjusting #17 (sensitivity control) does the IF stage oscillate? About 1/4 of a turn ccw from the point of oscillation is where you want to be. A little bit less than that the audio will sound rather bassy. Past that point (cw) it will squeal as you tune across each station.  Be careful not to over tighten the fiber nut it cracks easily.

When adjusting #'s 11 and 15 do you get a reasonable peak at 460kc? Regenerative detectors are pretty sensitive and can be overloaded when applying a strong signal from a generator so keep level down to a minimum when aligning.

Is the spkr at fault? Stiff spider, off center cone, rubbing voice coil, or a dirty pole gap can limit the movement of the cone and decrees the volume. 

Check chassis ground connections that use rivets. I haven't had any low volume issues but have had noise and hum problems. 

The model 80, 81, 84, and a few the 50's and 600's use very similar circuits. These were entree level sets and had their limitation. It's a bare bones autodyne mixer, regen detector, and power amp. In one respect low sensitivity is a good thing as it only has one IF transformer to give it some selectivity. The design is balance between selectivity and sensitivity. Everything needs to be working well on these sets to get good performance. A weak tube, out of alignment or an out of tolerance resistor in the det circuit can ruin the performance. 

Not sure what you are using for an antenna but the longer and higher the better. If you are using a couple of feet scrap hookup wire in the basement your probably not going to hear much.

RE: Philco 84 Low Volume - dconant - 10-14-2025

Yes on resistors as well as the rest of them. I'm pretty picky as for how far off they can be. Probably less than 5 percent.
I adjusted #17 until squeal and backed off about 1/4 turn as you said. No squealing anywhere.
Yes 11 and 15 peak good.
I tried another speaker (PM) and it sounds the same. No rubbing on original speaker.
Someone before me soldered all chassis grounds.
My antenna is over 100' from house to several trees. Since I can pickup two Canadian stations about 100 miles away I'd say its doing pretty good. Plus ground is to a ground rod separate from house ground.