[Hallicrafters] FPM-300 question

Sun Jul 29 18:57:25 EDT 2012

Great Bob,
They sure are a fun rig.
Another change I made was to separate the main tuning knob skirt from the 
knob.  I then marked every 5th hashmark in red. Along with some machining 
and a pressure plate, I can now slip the KHz disc to line up with the 
calibrator- ala the Drake 4 line. This gives surpisingly good 1KHz readout.
I spent a lot of time cleaning mine up and I also  had the cabinet powder 
coated.
My output is still  low- maybe 90W on 40, 85W on 20M etc. 80M is the lowest 
at 50W and this  leads me to suspect the premixer area. I say this because 
all bands except 80M have  another gain stage- Q404.
I only need 16W or so though to drive my SPE Expert amp to a KW, but it 
still bugs me.

The CW signal, despite being a 1400Hz audio tone applied to SSB, is quite 
clean. The closest product I see is -40dBC.
Let me know if I can help.

Dale W4OP

----- Original Message ----- 
From: "Bob Flye" <swlandham at rocketmail.com>
To: "Dale Parfitt" <parinc1 at frontier.com>; <Hallicrafters at mailman.qth.net>
Sent: Sunday, July 29, 2012 6:40 PM
Subject: Re: [Hallicrafters] FPM-300 question

Thanks Dale!
I appreciate the input. The 12 volts is not shorted to ground, it starts out 
at about 18 Ohms and goes up to 110 Ohms as the electrolytics charge. 18 
Ohms at 12 volts is only 600 mA, which is well below the 1.5 amp rating of 
the bridge. I think I want to change C106 before I add the jumper, $1.98 is 
cheap insurance against a bad electrolytic. The 3000 uF cap has already been 
changed.
The inside of mine is dusty, you cannot even see into the final tube it is 
so bad, I was really impressed by how clean and nice yours is, thanks for 
the link. This is going to be a fun project, I am taking it slow so I do not 
blow it up.

72/73
Bob, AD7BP

"You are boldly going where no man knows what he is doing"  -Maarten 
Schmidt, Palomar astronomer-

----- Original Message -----
From: Dale Parfitt <parinc1 at frontier.com>
To: Bob Flye <swlandham at rocketmail.com>; Hallicrafters at mailman.qth.net
Cc:
Sent: Sunday, July 29, 2012 2:27 PM
Subject: Re: [Hallicrafters] FPM-300 question

Hi Bob,
In my manual, pins 5-6 are jumpered for AC operation.
12-14 AC ground
8 is AC hot
2 is AC neutral
Although my schematic does not show it, 4-7 are jumpered on my plug. I see
no other way for 12.6VDC to get back to the rig- as you said. Have you put
an Ohm meter on the 12.6VDC line to see if it is shorted to ground?

Brand new stainless cabinet clasps are still available.
I would highly recommend, once you get her running that you install a
Cumbria Designs X-Lock VFO stabilizer. With it installed, the rig sits
within 10Hz all day long. Without it, there is constant drfit even when just
receiving.
You can check out my 300 at:
http://www.parelectronics.com/vintage-hallicrafters-fpm-300.php
GL,
Dale W4OP

----- Original Message ----- 
From: "Bob Flye" <swlandham at rocketmail.com>
To: <Hallicrafters at mailman.qth.net>
Sent: Sunday, July 29, 2012 4:23 PM
Subject: [Hallicrafters] FPM-300 question

Greetings all,
I am new to the list. I just got an FPM-300 radio that is in need of repair.
The D303 bridge on the power supply board was toasted, and several caps were
obviously in need of replacement. I took care of all of those. When I
powered it up, there was nothing, well, except for the hum of the rig. I
have one question, I found pins 4 and 7 jumpered on the Jones plug, since it
was not in the original schematic, I clipped it out, but looking further, it
looks like pins 4 and 7 NEED to be jumpered to get 12 volts to the circuit
boards. As an aside, pins 4 and 7 were penciled in on the schematic as
connected. The D303 mentioned above is the one that supplies 12 volts also.

Does pin 4 and 7 need to be jumpered?
How bad is it to change the drive belt for band changing? I got a drive belt
on ebay, it is run with cord now.

More questions will come up as I get deeper into the rig.

THANKS!!!!
72/73
Bob, AD7BP

"You are boldly going where no man knows what he is doing" -Maarten Schmidt,
Palomar astronomer-
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Version: 2012.0.2197 / Virus Database: 2437/5163 - Release Date: 07/29/12